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  • Functional Adaptation

    - by Charles Courchaine
    In real life and OO programming we’re often faced with using adapters, DVI to VGA, 1/4” to 1/8” audio connections, 110V to 220V, wrapping an incompatible interface with a new one, and so on.  Where the adapter pattern is generally considered for interfaces and classes a similar technique can be applied to method signatures.  To be fair, this adaptation is generally used to reduce the number of parameters but I’m sure there are other clever possibilities to be had.  As Jan questioned in the last post, how can we use a common method to execute an action if the action has a differing number of parameters, going back to the greeting example it was suggested having an AddName method that takes a first and last name as parameters.  This is exactly what we’ll address in this post. Let’s set the stage with some review and some code changes.  First, our method that handles the setup/tear-down infrastructure for our WCF service: 1: private static TResult ExecuteGreetingFunc<TResult>(Func<IGreeting, TResult> theGreetingFunc) 2: { 3: IGreeting aGreetingService = null; 4: try 5: { 6: aGreetingService = GetGreetingChannel(); 7: return theGreetingFunc(aGreetingService); 8: } 9: finally 10: { 11: CloseWCFChannel((IChannel)aGreetingService); 12: } 13: } Our original AddName method: 1: private static string AddName(string theName) 2: { 3: return ExecuteGreetingFunc<string>(theGreetingService => theGreetingService.AddName(theName)); 4: } Our new AddName method: 1: private static int AddName(string firstName, string lastName) 2: { 3: return ExecuteGreetingFunc<int>(theGreetingService => theGreetingService.AddName(firstName, lastName)); 4: } Let’s change the AddName method, just a little bit more for this example and have it take the greeting service as a parameter. 1: private static int AddName(IGreeting greetingService, string firstName, string lastName) 2: { 3: return greetingService.AddName(firstName, lastName); 4: } The new signature of AddName using the Func delegate is now Func<IGreeting, string, string, int>, which can’t be used with ExecuteGreetingFunc as is because it expects Func<IGreeting, TResult>.  Somehow we have to eliminate the two string parameters before we can use this with our existing method.  This is where we need to adapt AddName to match what ExecuteGreetingFunc expects, and we’ll do so in the following progression. 1: Func<IGreeting, string, string, int> -> Func<IGreeting, string, int> 2: Func<IGreeting, string, int> -> Func<IGreeting, int>   For the first step, we’ll create a method using the lambda syntax that will “eliminate” the last name parameter: 1: string lastNameToAdd = "Smith"; 2: //Func<IGreeting, string, string, int> -> Func<IGreeting, string, int> 3: Func<IGreeting, string, int> addName = (greetingService, firstName) => AddName(greetingService, firstName, lastNameToAdd); The new addName method gets us one step close to the signature we need.  Let’s say we’re going to call this in a loop to add several names, we’ll take the final step from Func<IGreeting, string, int> -> Func<IGreeting, int> in line as a lambda passed to ExecuteGreetingFunc like so: 1: List<string> firstNames = new List<string>() { "Bob", "John" }; 2: int aID; 3: foreach (string firstName in firstNames) 4: { 5: //Func<IGreeting, string, int> -> Func<IGreeting, int> 6: aID = ExecuteGreetingFunc<int>(greetingService => addName(greetingService, firstName)); 7: Console.WriteLine(GetGreeting(aID)); 8: } If for some reason you needed to break out the lambda on line 6 you could replace it with 1: aID = ExecuteGreetingFunc<int>(ApplyAddName(addName, firstName)); and use this method: 1: private static Func<IGreeting, int> ApplyAddName(Func<IGreeting, string, int> addName, string lastName) 2: { 3: return greetingService => addName(greetingService, lastName); 4: } Splitting out a lambda into its own method is useful both in this style of coding as well as LINQ queries to improve the debugging experience.  It is not strictly necessary to break apart the steps & functions as was shown above; the lambda in line 6 (of the foreach example) could include both the last name and first name instead of being composed of two functions.  The process demonstrated above is one of partially applying functions, this could have also been done with Currying (also see Dustin Campbell’s excellent post on Currying for the canonical curried add example).  Matthew Podwysocki also has some good posts explaining both Currying and partial application and a follow up post that further clarifies the difference between Currying and partial application.  In either technique the ultimate goal is to reduce the number of parameters passed to a function.  Currying makes it a single parameter passed at each step, where partial application allows one to use multiple parameters at a time as we’ve done here.  This technique isn’t for everyone or every problem, but can be extremely handy when you need to adapt a call to something you don’t control.

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  • Windows Azure: Import/Export Hard Drives, VM ACLs, Web Sockets, Remote Debugging, Continuous Delivery, New Relic, Billing Alerts and More

    - by ScottGu
    Two weeks ago we released a giant set of improvements to Windows Azure, as well as a significant update of the Windows Azure SDK. This morning we released another massive set of enhancements to Windows Azure.  Today’s new capabilities include: Storage: Import/Export Hard Disk Drives to your Storage Accounts HDInsight: General Availability of our Hadoop Service in the cloud Virtual Machines: New VM Gallery, ACL support for VIPs Web Sites: WebSocket and Remote Debugging Support Notification Hubs: Segmented customer push notification support with tag expressions TFS & GIT: Continuous Delivery Support for Web Sites + Cloud Services Developer Analytics: New Relic support for Web Sites + Mobile Services Service Bus: Support for partitioned queues and topics Billing: New Billing Alert Service that sends emails notifications when your bill hits a threshold you define All of these improvements are now available to use immediately (note that some features are still in preview).  Below are more details about them. Storage: Import/Export Hard Disk Drives to Windows Azure I am excited to announce the preview of our new Windows Azure Import/Export Service! The Windows Azure Import/Export Service enables you to move large amounts of on-premises data into and out of your Windows Azure Storage accounts. It does this by enabling you to securely ship hard disk drives directly to our Windows Azure data centers. Once we receive the drives we’ll automatically transfer the data to or from your Windows Azure Storage account.  This enables you to import or export massive amounts of data more quickly and cost effectively (and not be constrained by available network bandwidth). Encrypted Transport Our Import/Export service provides built-in support for BitLocker disk encryption – which enables you to securely encrypt data on the hard drives before you send it, and not have to worry about it being compromised even if the disk is lost/stolen in transit (since the content on the transported hard drives is completely encrypted and you are the only one who has the key to it).  The drive preparation tool we are shipping today makes setting up bitlocker encryption on these hard drives easy. How to Import/Export your first Hard Drive of Data You can read our Getting Started Guide to learn more about how to begin using the import/export service.  You can create import and export jobs via the Windows Azure Management Portal as well as programmatically using our Server Management APIs. It is really easy to create a new import or export job using the Windows Azure Management Portal.  Simply navigate to a Windows Azure storage account, and then click the new Import/Export tab now available within it (note: if you don’t have this tab make sure to sign-up for the Import/Export preview): Then click the “Create Import Job” or “Create Export Job” commands at the bottom of it.  This will launch a wizard that easily walks you through the steps required: For more comprehensive information about Import/Export, refer to Windows Azure Storage team blog.  You can also send questions and comments to the [email protected] email address. We think you’ll find this new service makes it much easier to move data into and out of Windows Azure, and it will dramatically cut down the network bandwidth required when working on large data migration projects.  We hope you like it. HDInsight: 100% Compatible Hadoop Service in the Cloud Last week we announced the general availability release of Windows Azure HDInsight. HDInsight is a 100% compatible Hadoop service that allows you to easily provision and manage Hadoop clusters for big data processing in Windows Azure.  This release is now live in production, backed by an enterprise SLA, supported 24x7 by Microsoft Support, and is ready to use for production scenarios. HDInsight allows you to use Apache Hadoop tools, such as Pig and Hive, to process large amounts of data in Windows Azure Blob Storage. Because data is stored in Windows Azure Blob Storage, you can choose to dynamically create Hadoop clusters only when you need them, and then shut them down when they are no longer required (since you pay only for the time the Hadoop cluster instances are running this provides a super cost effective way to use them).  You can create Hadoop clusters using either the Windows Azure Management Portal (see below) or using our PowerShell and Cross Platform Command line tools: The import/export hard drive support that came out today is a perfect companion service to use with HDInsight – the combination allows you to easily ingest, process and optionally export a limitless amount of data.  We’ve also integrated HDInsight with our Business Intelligence tools, so users can leverage familiar tools like Excel in order to analyze the output of jobs.  You can find out more about how to get started with HDInsight here. Virtual Machines: VM Gallery Enhancements Today’s update of Windows Azure brings with it a new Virtual Machine gallery that you can use to create new VMs in the cloud.  You can launch the gallery by doing New->Compute->Virtual Machine->From Gallery within the Windows Azure Management Portal: The new Virtual Machine Gallery includes some nice enhancements that make it even easier to use: Search: You can now easily search and filter images using the search box in the top-right of the dialog.  For example, simply type “SQL” and we’ll filter to show those images in the gallery that contain that substring. Category Tree-view: Each month we add more built-in VM images to the gallery.  You can continue to browse these using the “All” view within the VM Gallery – or now quickly filter them using the category tree-view on the left-hand side of the dialog.  For example, by selecting “Oracle” in the tree-view you can now quickly filter to see the official Oracle supplied images. MSDN and Supported checkboxes: With today’s update we are also introducing filters that makes it easy to filter out types of images that you may not be interested in. The first checkbox is MSDN: using this filter you can exclude any image that is not part of the Windows Azure benefits for MSDN subscribers (which have highly discounted pricing - you can learn more about the MSDN pricing here). The second checkbox is Supported: this filter will exclude any image that contains prerelease software, so you can feel confident that the software you choose to deploy is fully supported by Windows Azure and our partners. Sort options: We sort gallery images by what we think customers are most interested in, but sometimes you might want to sort using different views. So we’re providing some additional sort options, like “Newest,” to customize the image list for what suits you best. Pricing information: We now provide additional pricing information about images and options on how to cost effectively run them directly within the VM Gallery. The above improvements make it even easier to use the VM Gallery and quickly create launch and run Virtual Machines in the cloud. Virtual Machines: ACL Support for VIPs A few months ago we exposed the ability to configure Access Control Lists (ACLs) for Virtual Machines using Windows PowerShell cmdlets and our Service Management API. With today’s release, you can now configure VM ACLs using the Windows Azure Management Portal as well. You can now do this by clicking the new Manage ACL command in the Endpoints tab of a virtual machine instance: This will enable you to configure an ordered list of permit and deny rules to scope the traffic that can access your VM’s network endpoints. For example, if you were on a virtual network, you could limit RDP access to a Windows Azure virtual machine to only a few computers attached to your enterprise. Or if you weren’t on a virtual network you could alternatively limit traffic from public IPs that can access your workloads: Here is the default behaviors for ACLs in Windows Azure: By default (i.e. no rules specified), all traffic is permitted. When using only Permit rules, all other traffic is denied. When using only Deny rules, all other traffic is permitted. When there is a combination of Permit and Deny rules, all other traffic is denied. Lastly, remember that configuring endpoints does not automatically configure them within the VM if it also has firewall rules enabled at the OS level.  So if you create an endpoint using the Windows Azure Management Portal, Windows PowerShell, or REST API, be sure to also configure your guest VM firewall appropriately as well. Web Sites: Web Sockets Support With today’s release you can now use Web Sockets with Windows Azure Web Sites.  This feature enables you to easily integrate real-time communication scenarios within your web based applications, and is available at no extra charge (it even works with the free tier).  Higher level programming libraries like SignalR and socket.io are also now supported with it. You can enable Web Sockets support on a web site by navigating to the Configure tab of a Web Site, and by toggling Web Sockets support to “on”: Once Web Sockets is enabled you can start to integrate some really cool scenarios into your web applications.  Check out the new SignalR documentation hub on www.asp.net to learn more about some of the awesome scenarios you can do with it. Web Sites: Remote Debugging Support The Windows Azure SDK 2.2 we released two weeks ago introduced remote debugging support for Windows Azure Cloud Services. With today’s Windows Azure release we are extending this remote debugging support to also work with Windows Azure Web Sites. With live, remote debugging support inside of Visual Studio, you are able to have more visibility than ever before into how your code is operating live in Windows Azure. It is now super easy to attach the debugger and quickly see what is going on with your application in the cloud. Remote Debugging of a Windows Azure Web Site using VS 2013 Enabling the remote debugging of a Windows Azure Web Site using VS 2013 is really easy.  Start by opening up your web application’s project within Visual Studio. Then navigate to the “Server Explorer” tab within Visual Studio, and click on the deployed web-site you want to debug that is running within Windows Azure using the Windows Azure->Web Sites node in the Server Explorer.  Then right-click and choose the “Attach Debugger” option on it: When you do this Visual Studio will remotely attach the debugger to the Web Site running within Windows Azure.  The debugger will then stop the web site’s execution when it hits any break points that you have set within your web application’s project inside Visual Studio.  For example, below I set a breakpoint on the “ViewBag.Message” assignment statement within the HomeController of the standard ASP.NET MVC project template.  When I hit refresh on the “About” page of the web site within the browser, the breakpoint was triggered and I am now able to debug the app remotely using Visual Studio: Note above how we can debug variables (including autos/watchlist/etc), as well as use the Immediate and Command Windows. In the debug session above I used the Immediate Window to explore some of the request object state, as well as to dynamically change the ViewBag.Message property.  When we click the the “Continue” button (or press F5) the app will continue execution and the Web Site will render the content back to the browser.  This makes it super easy to debug web apps remotely. Tips for Better Debugging To get the best experience while debugging, we recommend publishing your site using the Debug configuration within Visual Studio’s Web Publish dialog. This will ensure that debug symbol information is uploaded to the Web Site which will enable a richer debug experience within Visual Studio.  You can find this option on the Web Publish dialog on the Settings tab: When you ultimately deploy/run the application in production we recommend using the “Release” configuration setting – the release configuration is memory optimized and will provide the best production performance.  To learn more about diagnosing and debugging Windows Azure Web Sites read our new Troubleshooting Windows Azure Web Sites in Visual Studio guide. Notification Hubs: Segmented Push Notification support with tag expressions In August we announced the General Availability of Windows Azure Notification Hubs - a powerful Mobile Push Notifications service that makes it easy to send high volume push notifications with low latency from any mobile app back-end.  Notification hubs can be used with any mobile app back-end (including ones built using our Mobile Services capability) and can also be used with back-ends that run in the cloud as well as on-premises. Beginning with the initial release, Notification Hubs allowed developers to send personalized push notifications to both individual users as well as groups of users by interest, by associating their devices with tags representing the logical target of the notification. For example, by registering all devices of customers interested in a favorite MLB team with a corresponding tag, it is possible to broadcast one message to millions of Boston Red Sox fans and another message to millions of St. Louis Cardinals fans with a single API call respectively. New support for using tag expressions to enable advanced customer segmentation With today’s release we are adding support for even more advanced customer targeting.  You can now identify customers that you want to send push notifications to by defining rich tag expressions. With tag expressions, you can now not only broadcast notifications to Boston Red Sox fans, but take that segmenting a step farther and reach more granular segments. This opens up a variety of scenarios, for example: Offers based on multiple preferences—e.g. send a game day vegetarian special to users tagged as both a Boston Red Sox fan AND a vegetarian Push content to multiple segments in a single message—e.g. rain delay information only to users who are tagged as either a Boston Red Sox fan OR a St. Louis Cardinal fan Avoid presenting subsets of a segment with irrelevant content—e.g. season ticket availability reminder to users who are tagged as a Boston Red Sox fan but NOT also a season ticket holder To illustrate with code, consider a restaurant chain app that sends an offer related to a Red Sox vs Cardinals game for users in Boston. Devices can be tagged by your app with location tags (e.g. “Loc:Boston”) and interest tags (e.g. “Follows:RedSox”, “Follows:Cardinals”), and then a notification can be sent by your back-end to “(Follows:RedSox || Follows:Cardinals) && Loc:Boston” in order to deliver an offer to all devices in Boston that follow either the RedSox or the Cardinals. This can be done directly in your server backend send logic using the code below: var notification = new WindowsNotification(messagePayload); hub.SendNotificationAsync(notification, "(Follows:RedSox || Follows:Cardinals) && Loc:Boston"); In your expressions you can use all Boolean operators: AND (&&), OR (||), and NOT (!).  Some other cool use cases for tag expressions that are now supported include: Social: To “all my group except me” - group:id && !user:id Events: Touchdown event is sent to everybody following either team or any of the players involved in the action: Followteam:A || Followteam:B || followplayer:1 || followplayer:2 … Hours: Send notifications at specific times. E.g. Tag devices with time zone and when it is 12pm in Seattle send to: GMT8 && follows:thaifood Versions and platforms: Send a reminder to people still using your first version for Android - version:1.0 && platform:Android For help on getting started with Notification Hubs, visit the Notification Hub documentation center.  Then download the latest NuGet package (or use the Notification Hubs REST APIs directly) to start sending push notifications using tag expressions.  They are really powerful and enable a bunch of great new scenarios. TFS & GIT: Continuous Delivery Support for Web Sites + Cloud Services With today’s Windows Azure release we are making it really easy to enable continuous delivery support with Windows Azure and Team Foundation Services.  Team Foundation Services is a cloud based offering from Microsoft that provides integrated source control (with both TFS and Git support), build server, test execution, collaboration tools, and agile planning support.  It makes it really easy to setup a team project (complete with automated builds and test runners) in the cloud, and it has really rich integration with Visual Studio. With today’s Windows Azure release it is now really easy to enable continuous delivery support with both TFS and Git based repositories hosted using Team Foundation Services.  This enables a workflow where when code is checked in, built successfully on an automated build server, and all tests pass on it – I can automatically have the app deployed on Windows Azure with zero manual intervention or work required. The below screen-shots demonstrate how to quickly setup a continuous delivery workflow to Windows Azure with a Git-based ASP.NET MVC project hosted using Team Foundation Services. Enabling Continuous Delivery to Windows Azure with Team Foundation Services The project I’m going to enable continuous delivery with is a simple ASP.NET MVC project whose source code I’m hosting using Team Foundation Services.  I did this by creating a “SimpleContinuousDeploymentTest” repository there using Git – and then used the new built-in Git tooling support within Visual Studio 2013 to push the source code to it.  Below is a screen-shot of the Git repository hosted within Team Foundation Services: I can access the repository within Visual Studio 2013 and easily make commits with it (as well as branch, merge and do other tasks).  Using VS 2013 I can also setup automated builds to take place in the cloud using Team Foundation Services every time someone checks in code to the repository: The cool thing about this is that I don’t have to buy or rent my own build server – Team Foundation Services automatically maintains its own build server farm and can automatically queue up a build for me (for free) every time someone checks in code using the above settings.  This build server (and automated testing) support now works with both TFS and Git based source control repositories. Connecting a Team Foundation Services project to Windows Azure Once I have a source repository hosted in Team Foundation Services with Automated Builds and Testing set up, I can then go even further and set it up so that it will be automatically deployed to Windows Azure when a source code commit is made to the repository (assuming the Build + Tests pass).  Enabling this is now really easy.  To set this up with a Windows Azure Web Site simply use the New->Compute->Web Site->Custom Create command inside the Windows Azure Management Portal.  This will create a dialog like below.  I gave the web site a name and then made sure the “Publish from source control” checkbox was selected: When we click next we’ll be prompted for the location of the source repository.  We’ll select “Team Foundation Services”: Once we do this we’ll be prompted for our Team Foundation Services account that our source repository is hosted under (in this case my TFS account is “scottguthrie”): When we click the “Authorize Now” button we’ll be prompted to give Windows Azure permissions to connect to the Team Foundation Services account.  Once we do this we’ll be prompted to pick the source repository we want to connect to.  Starting with today’s Windows Azure release you can now connect to both TFS and Git based source repositories.  This new support allows me to connect to the “SimpleContinuousDeploymentTest” respository we created earlier: Clicking the finish button will then create the Web Site with the continuous delivery hooks setup with Team Foundation Services.  Now every time someone pushes source control to the repository in Team Foundation Services, it will kick off an automated build, run all of the unit tests in the solution , and if they pass the app will be automatically deployed to our Web Site in Windows Azure.  You can monitor the history and status of these automated deployments using the Deployments tab within the Web Site: This enables a really slick continuous delivery workflow, and enables you to build and deploy apps in a really nice way. Developer Analytics: New Relic support for Web Sites + Mobile Services With today’s Windows Azure release we are making it really easy to enable Developer Analytics and Monitoring support with both Windows Azure Web Site and Windows Azure Mobile Services.  We are partnering with New Relic, who provide a great dev analytics and app performance monitoring offering, to enable this - and we have updated the Windows Azure Management Portal to make it really easy to configure. Enabling New Relic with a Windows Azure Web Site Enabling New Relic support with a Windows Azure Web Site is now really easy.  Simply navigate to the Configure tab of a Web Site and scroll down to the “developer analytics” section that is now within it: Clicking the “add-on” button will display some additional UI.  If you don’t already have a New Relic subscription, you can click the “view windows azure store” button to obtain a subscription (note: New Relic has a perpetually free tier so you can enable it even without paying anything): Clicking the “view windows azure store” button will launch the integrated Windows Azure Store experience we have within the Windows Azure Management Portal.  You can use this to browse from a variety of great add-on services – including New Relic: Select “New Relic” within the dialog above, then click the next button, and you’ll be able to choose which type of New Relic subscription you wish to purchase.  For this demo we’ll simply select the “Free Standard Version” – which does not cost anything and can be used forever:  Once we’ve signed-up for our New Relic subscription and added it to our Windows Azure account, we can go back to the Web Site’s configuration tab and choose to use the New Relic add-on with our Windows Azure Web Site.  We can do this by simply selecting it from the “add-on” dropdown (it is automatically populated within it once we have a New Relic subscription in our account): Clicking the “Save” button will then cause the Windows Azure Management Portal to automatically populate all of the needed New Relic configuration settings to our Web Site: Deploying the New Relic Agent as part of a Web Site The final step to enable developer analytics using New Relic is to add the New Relic runtime agent to our web app.  We can do this within Visual Studio by right-clicking on our web project and selecting the “Manage NuGet Packages” context menu: This will bring up the NuGet package manager.  You can search for “New Relic” within it to find the New Relic agent.  Note that there is both a 32-bit and 64-bit edition of it – make sure to install the version that matches how your Web Site is running within Windows Azure (note: you can configure your Web Site to run in either 32-bit or 64-bit mode using the Web Site’s “Configuration” tab within the Windows Azure Management Portal): Once we install the NuGet package we are all set to go.  We’ll simply re-publish the web site again to Windows Azure and New Relic will now automatically start monitoring the application Monitoring a Web Site using New Relic Now that the application has developer analytics support with New Relic enabled, we can launch the New Relic monitoring portal to start monitoring the health of it.  We can do this by clicking on the “Add Ons” tab in the left-hand side of the Windows Azure Management Portal.  Then select the New Relic add-on we signed-up for within it.  The Windows Azure Management Portal will provide some default information about the add-on when we do this.  Clicking the “Manage” button in the tray at the bottom will launch a new browser tab and single-sign us into the New Relic monitoring portal associated with our account: When we do this a new browser tab will launch with the New Relic admin tool loaded within it: We can now see insights into how our app is performing – without having to have written a single line of monitoring code.  The New Relic service provides a ton of great built-in monitoring features allowing us to quickly see: Performance times (including browser rendering speed) for the overall site and individual pages.  You can optionally set alert thresholds to trigger if the speed does not meet a threshold you specify. Information about where in the world your customers are hitting the site from (and how performance varies by region) Details on the latency performance of external services your web apps are using (for example: SQL, Storage, Twitter, etc) Error information including call stack details for exceptions that have occurred at runtime SQL Server profiling information – including which queries executed against your database and what their performance was And a whole bunch more… The cool thing about New Relic is that you don’t need to write monitoring code within your application to get all of the above reports (plus a lot more).  The New Relic agent automatically enables the CLR profiler within applications and automatically captures the information necessary to identify these.  This makes it super easy to get started and immediately have a rich developer analytics view for your solutions with very little effort. If you haven’t tried New Relic out yet with Windows Azure I recommend you do so – I think you’ll find it helps you build even better cloud applications.  Following the above steps will help you get started and deliver you a really good application monitoring solution in only minutes. Service Bus: Support for partitioned queues and topics With today’s release, we are enabling support within Service Bus for partitioned queues and topics. Enabling partitioning enables you to achieve a higher message throughput and better availability from your queues and topics. Higher message throughput is achieved by implementing multiple message brokers for each partitioned queue and topic.  The  multiple messaging stores will also provide higher availability. You can create a partitioned queue or topic by simply checking the Enable Partitioning option in the custom create wizard for a Queue or Topic: Read this article to learn more about partitioned queues and topics and how to take advantage of them today. Billing: New Billing Alert Service Today’s Windows Azure update enables a new Billing Alert Service Preview that enables you to get proactive email notifications when your Windows Azure bill goes above a certain monetary threshold that you configure.  This makes it easier to manage your bill and avoid potential surprises at the end of the month. With the Billing Alert Service Preview, you can now create email alerts to monitor and manage your monetary credits or your current bill total.  To set up an alert first sign-up for the free Billing Alert Service Preview.  Then visit the account management page, click on a subscription you have setup, and then navigate to the new Alerts tab that is available: The alerts tab allows you to setup email alerts that will be sent automatically once a certain threshold is hit.  For example, by clicking the “add alert” button above I can setup a rule to send myself email anytime my Windows Azure bill goes above $100 for the month: The Billing Alert Service will evolve to support additional aspects of your bill as well as support multiple forms of alerts such as SMS.  Try out the new Billing Alert Service Preview today and give us feedback. Summary Today’s Windows Azure release enables a ton of great new scenarios, and makes building applications hosted in the cloud even easier. If you don’t already have a Windows Azure account, you can sign-up for a free trial and start using all of the above features today.  Then visit the Windows Azure Developer Center to learn more about how to build apps with it. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • A Reusable Builder Class for Ruby Testing

    - by Liam McLennan
    My last post was about a class for building test data objects in C#. This post describes the same tool, but implemented in Ruby. The C# version was written first but I originally came up with the solution in my head using Ruby, and then I translated it to C#. The Ruby version was easier to write and is easier to use thanks to Ruby’s dynamic nature making generics unnecessary.  Here are my example domain classes: class Person attr_accessor :name, :age def initialize(name, age) @name = name @age = age end end class Property attr_accessor :street, :manager def initialize(street, manager) @street = street @manager = manager end end and the test class showing what the builder does: class Test_Builder < Test::Unit::TestCase def setup @build = Builder.new @build.configure({ Property => lambda { Property.new '127 Creek St', @build.a(Person) }, Person => lambda { Person.new 'Liam', 26 } }) end def test_create assert_not_nil @build end def test_can_get_a_person @person = @build.a(Person) assert_not_nil @person assert_equal 'Liam', @person.name assert_equal 26, @person.age end def test_can_get_a_modified_person @person = @build.a Person do |person| person.age = 999 end assert_not_nil @person assert_equal 'Liam', @person.name assert_equal 999, @person.age end def test_can_get_a_different_type_that_depends_on_a_type_that_has_not_been_configured_yet @my_place = @build.a(Property) assert_not_nil @my_place assert_equal '127 Creek St', @my_place.street assert_equal @build.a(Person).name, @my_place.manager.name end end Finally, the implementation of Builder: class Builder # defaults is a hash of Class => creation lambda def configure defaults @defaults = defaults end def a(klass) temp = @defaults[klass].call() yield temp if block_given? temp end end

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  • We'll be at QCon San Francisco!

    - by Carlos Chang
    Oracle Technology Network is a Platinum sponsor at QCon San Francisco. Don’t miss these great developer focused sessions: Shay Shmeltzer - How we simplified Web, Mobile and Cloud development for our own developers? - the Oracle Story Over the past several years, Oracle has beendeveloping a new set of enterprise applications in what is probably one of the largest Java based development project in the world. How do you take 3000 developers and make them productive? How do you insure the delivery of cutting edge UIs for both Mobile and Web channels? How do you enable Cloud based development and deployment? Come and learn how we did it at Oracle, and see how the same technologies and methodologies can apply to your development efforts. Dan Smith - Project Lambda in Java 8 Java SE 8 will include major enhancements to the Java Programming Language and its core libraries.  This suite of new features, known as Project Lambda in the OpenJDK community, includes lambda expressions, default methods, and parallel collections (and much more!).  The result will be a next-generation Java programming experience with more flexibility and better abstractions.   This talk will introduce the new Java features and offer a behind-the-scenes view of how they evolved and why they work the way that they do. Arun Gupta - JSR 356: Building HTML5 WebSocket Applications in Java The family of HTML5 technologies has pushed the pendulum away from rich client technologies and toward ever-more-capable Web clients running on today’s browsers. In particular, WebSocket brings new opportunities for efficient peer-to-peer communication, providing the basis for a new generation of interactive and “live” Web applications. This session examines the efforts under way to support WebSocket in the Java programming model, from its base-level integration in the Java Servlet and Java EE containers to a new, easy-to-use API and toolset that are destined to become part of the standard Java platform. The complete conference schedule is here: http://qconsf.com/sf2012/schedule/wednesday.jsp But wait, there’s more! At the Oracle booth, we’ll also be covering: Oracle ADF Mobile Oracle Developer Cloud Service Oracle ADF Essentials NetBeans Project Easel Hope to see you there! 

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  • Ad-hoc String Manipulation With Visual Studio

    - by Liam McLennan
    Visual studio supports relatively advanced string manipulation via the ‘Quick Replace’ dialog. Today I had a requirement to modify some html, replacing line breaks with unordered list items. For example, I need to convert: Infrastructure<br/> Energy<br/> Industrial development<br/> Urban growth<br/> Water<br/> Food security<br/> to: <li>Infrastructure</li> <li>Energy</li> <li>Industrial development</li> <li>Urban growth</li> <li>Water</li> <li>Food security</li> This cannot be done with a simple search-and-replace but it can be done using the Quick Replace regular expression support. To use regular expressions expand ‘Find Options’, check ‘Use:’ and select ‘Regular Expressions’ Typically, Visual Studio regular expressions use a different syntax to every other regular expression engine. We need to use a capturing group to grab the text of each line so that it can be included in the replacement. The syntax for a capturing group is to replace the part of the expression to be captured with { and }. So my regular expression: {.*}\<br/\> means capture all the characters before <br/>. Note that < and > have to be escaped with \. In the replacement expression we can use \1 to insert the previously captured text. If the search expression had a second capturing group then its text would be available in \2 and so on. Visual Studio’s quick replace feature can be scoped to a selection, the current document, all open documents or every document in the current solution.

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  • Languages with a clear distinction between subroutines that are purely functional, mutating, state-changing, etc?

    - by CPX
    Lately I've become more and more frustrated that in most modern programming languages I've worked with (C/C++, C#, F#, Ruby, Python, JS and more) there is very little, if any, language support for determining what a subroutine will actually do. Consider the following simple pseudo-code: var x = DoSomethingWith(y); How do I determine what the call to DoSomethingWith(y) will actually do? Will it mutate y, or will it return a copy of y? Does it depend on global or local state, or is it only dependent on y? Will it change the global or local state? How does closure affect the outcome of the call? In all languages I've encountered, almost none of these questions can be answered by merely looking at the signature of the subroutine, and there is almost never any compile-time or run-time support either. Usually, the only way is to put your trust in the author of the API, and hope that the documentation and/or naming conventions reveal what the subroutine will actually do. My question is this: Does there exist any languages today that make symbolic distinctions between these types of scenarios, and places compile-time constraints on what code you can actually write? (There is of course some support for this in most modern languages, such as different levels of scope and closure, the separation between static and instance code, lambda functions, et cetera. But too often these seem to come into conflict with each other. For instance, a lambda function will usually either be purely functional, and simply return a value based on input parameters, or mutate the input parameters in some way. But it is usually possible to access static variables from a lambda function, which in turn can give you access to instance variables, and then it all breaks apart.)

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  • Microsoft and jQuery

    - by Rick Strahl
    The jQuery JavaScript library has been steadily getting more popular and with recent developments from Microsoft, jQuery is also getting ever more exposure on the ASP.NET platform including now directly from Microsoft. jQuery is a light weight, open source DOM manipulation library for JavaScript that has changed how many developers think about JavaScript. You can download it and find more information on jQuery on www.jquery.com. For me jQuery has had a huge impact on how I develop Web applications and was probably the main reason I went from dreading to do JavaScript development to actually looking forward to implementing client side JavaScript functionality. It has also had a profound impact on my JavaScript skill level for me by seeing how the library accomplishes things (and often reviewing the terse but excellent source code). jQuery made an uncomfortable development platform (JavaScript + DOM) a joy to work on. Although jQuery is by no means the only JavaScript library out there, its ease of use, small size, huge community of plug-ins and pure usefulness has made it easily the most popular JavaScript library available today. As a long time jQuery user, I’ve been excited to see the developments from Microsoft that are bringing jQuery to more ASP.NET developers and providing more integration with jQuery for ASP.NET’s core features rather than relying on the ASP.NET AJAX library. Microsoft and jQuery – making Friends jQuery is an open source project but in the last couple of years Microsoft has really thrown its weight behind supporting this open source library as a supported component on the Microsoft platform. When I say supported I literally mean supported: Microsoft now offers actual tech support for jQuery as part of their Product Support Services (PSS) as jQuery integration has become part of several of the ASP.NET toolkits and ships in several of the default Web project templates in Visual Studio 2010. The ASP.NET MVC 3 framework (still in Beta) also uses jQuery for a variety of client side support features including client side validation and we can look forward toward more integration of client side functionality via jQuery in both MVC and WebForms in the future. In other words jQuery is becoming an optional but included component of the ASP.NET platform. PSS support means that support staff will answer jQuery related support questions as part of any support incidents related to ASP.NET which provides some piece of mind to some corporate development shops that require end to end support from Microsoft. In addition to including jQuery and supporting it, Microsoft has also been getting involved in providing development resources for extending jQuery’s functionality via plug-ins. Microsoft’s last version of the Microsoft Ajax Library – which is the successor to the native ASP.NET AJAX Library – included some really cool functionality for client templates, databinding and localization. As it turns out Microsoft has rebuilt most of that functionality using jQuery as the base API and provided jQuery plug-ins of these components. Very recently these three plug-ins were submitted and have been approved for inclusion in the official jQuery plug-in repository and been taken over by the jQuery team for further improvements and maintenance. Even more surprising: The jQuery-templates component has actually been approved for inclusion in the next major update of the jQuery core in jQuery V1.5, which means it will become a native feature that doesn’t require additional script files to be loaded. Imagine this – an open source contribution from Microsoft that has been accepted into a major open source project for a core feature improvement. Microsoft has come a long way indeed! What the Microsoft Involvement with jQuery means to you For Microsoft jQuery support is a strategic decision that affects their direction in client side development, but nothing stopped you from using jQuery in your applications prior to Microsoft’s official backing and in fact a large chunk of developers did so readily prior to Microsoft’s announcement. Official support from Microsoft brings a few benefits to developers however. jQuery support in Visual Studio 2010 means built-in support for jQuery IntelliSense, automatically added jQuery scripts in many projects types and a common base for client side functionality that actually uses what most developers are already using. If you have already been using jQuery and were worried about straying from the Microsoft line and their internal Microsoft Ajax Library – worry no more. With official support and the change in direction towards jQuery Microsoft is now following along what most in the ASP.NET community had already been doing by using jQuery, which is likely the reason for Microsoft’s shift in direction in the first place. ASP.NET AJAX and the Microsoft AJAX Library weren’t bad technology – there was tons of useful functionality buried in these libraries. However, these libraries never got off the ground, mainly because early incarnations were squarely aimed at control/component developers rather than application developers. For all the functionality that these controls provided for control developers they lacked in useful and easily usable application developer functionality that was easily accessible in day to day client side development. The result was that even though Microsoft shipped support for these tools in the box (in .NET 3.5 and 4.0), other than for the internal support in ASP.NET for things like the UpdatePanel and the ASP.NET AJAX Control Toolkit as well as some third party vendors, the Microsoft client libraries were largely ignored by the developer community opening the door for other client side solutions. Microsoft seems to be acknowledging developer choice in this case: Many more developers were going down the jQuery path rather than using the Microsoft built libraries and there seems to be little sense in continuing development of a technology that largely goes unused by the majority of developers. Kudos for Microsoft for recognizing this and gracefully changing directions. Note that even though there will be no further development in the Microsoft client libraries they will continue to be supported so if you’re using them in your applications there’s no reason to start running for the exit in a panic and start re-writing everything with jQuery. Although that might be a reasonable choice in some cases, jQuery and the Microsoft libraries work well side by side so that you can leave existing solutions untouched even as you enhance them with jQuery. The Microsoft jQuery Plug-ins – Solid Core Features One of the most interesting developments in Microsoft’s embracing of jQuery is that Microsoft has started contributing to jQuery via standard mechanism set for jQuery developers: By submitting plug-ins. Microsoft took some of the nicest new features of the unpublished Microsoft Ajax Client Library and re-wrote these components for jQuery and then submitted them as plug-ins to the jQuery plug-in repository. Accepted plug-ins get taken over by the jQuery team and that’s exactly what happened with the three plug-ins submitted by Microsoft with the templating plug-in even getting slated to be published as part of the jQuery core in the next major release (1.5). The following plug-ins are provided by Microsoft: jQuery Templates – a client side template rendering engine jQuery Data Link – a client side databinder that can synchronize changes without code jQuery Globalization – provides formatting and conversion features for dates and numbers The first two are ports of functionality that was slated for the Microsoft Ajax Library while functionality for the globalization library provides functionality that was already found in the original ASP.NET AJAX library. To me all three plug-ins address a pressing need in client side applications and provide functionality I’ve previously used in other incarnations, but with more complete implementations. Let’s take a close look at these plug-ins. jQuery Templates http://api.jquery.com/category/plugins/templates/ Client side templating is a key component for building rich JavaScript applications in the browser. Templating on the client lets you avoid from manually creating markup by creating DOM nodes and injecting them individually into the document via code. Rather you can create markup templates – similar to the way you create classic ASP server markup – and merge data into these templates to render HTML which you can then inject into the document or replace existing content with. Output from templates are rendered as a jQuery matched set and can then be easily inserted into the document as needed. Templating is key to minimize client side code and reduce repeated code for rendering logic. Instead a single template can be used in many places for updating and adding content to existing pages. Further if you build pure AJAX interfaces that rely entirely on client rendering of the initial page content, templates allow you to a use a single markup template to handle all rendering of each specific HTML section/element. I’ve used a number of different client rendering template engines with jQuery in the past including jTemplates (a PHP style templating engine) and a modified version of John Resig’s MicroTemplating engine which I built into my own set of libraries because it’s such a commonly used feature in my client side applications. jQuery templates adds a much richer templating model that allows for sub-templates and access to the data items. Like John Resig’s original Micro Template engine, the core basics of the templating engine create JavaScript code which means that templates can include JavaScript code. To give you a basic idea of how templates work imagine I have an application that downloads a set of stock quotes based on a symbol list then displays them in the document. To do this you can create an ‘item’ template that describes how each of the quotes is renderd as a template inside of the document: <script id="stockTemplate" type="text/x-jquery-tmpl"> <div id="divStockQuote" class="errordisplay" style="width: 500px;"> <div class="label">Company:</div><div><b>${Company}(${Symbol})</b></div> <div class="label">Last Price:</div><div>${LastPrice}</div> <div class="label">Net Change:</div><div> {{if NetChange > 0}} <b style="color:green" >${NetChange}</b> {{else}} <b style="color:red" >${NetChange}</b> {{/if}} </div> <div class="label">Last Update:</div><div>${LastQuoteTimeString}</div> </div> </script> The ‘template’ is little more than HTML with some markup expressions inside of it that define the template language. Notice the embedded ${} expressions which reference data from the quote objects returned from an AJAX call on the server. You can embed any JavaScript or value expression in these template expressions. There are also a number of structural commands like {{if}} and {{each}} that provide for rudimentary logic inside of your templates as well as commands ({{tmpl}} and {{wrap}}) for nesting templates. You can find more about the full set of markup expressions available in the documentation. To load up this data you can use code like the following: <script type="text/javascript"> //var Proxy = new ServiceProxy("../PageMethods/PageMethodsService.asmx/"); $(document).ready(function () { $("#btnGetQuotes").click(GetQuotes); }); function GetQuotes() { var symbols = $("#txtSymbols").val().split(","); $.ajax({ url: "../PageMethods/PageMethodsService.asmx/GetStockQuotes", data: JSON.stringify({ symbols: symbols }), // parameter map type: "POST", // data has to be POSTed contentType: "application/json", timeout: 10000, dataType: "json", success: function (result) { var quotes = result.d; var jEl = $("#stockTemplate").tmpl(quotes); $("#quoteDisplay").empty().append(jEl); }, error: function (xhr, status) { alert(status + "\r\n" + xhr.responseText); } }); }; </script> In this case an ASMX AJAX service is called to retrieve the stock quotes. The service returns an array of quote objects. The result is returned as an object with the .d property (in Microsoft service style) that returns the actual array of quotes. The template is applied with: var jEl = $("#stockTemplate").tmpl(quotes); which selects the template script tag and uses the .tmpl() function to apply the data to it. The result is a jQuery matched set of elements that can then be appended to the quote display element in the page. The template is merged against an array in this example. When the result is an array the template is automatically applied to each each array item. If you pass a single data item – like say a stock quote – the template works exactly the same way but is applied only once. Templates also have access to a $data item which provides the current data item and information about the tempalte that is currently executing. This makes it possible to keep context within the context of the template itself and also to pass context from a parent template to a child template which is very powerful. Templates can be evaluated by using the template selector and calling the .tmpl() function on the jQuery matched set as shown above or you can use the static $.tmpl() function to provide a template as a string. This allows you to dynamically create templates in code or – more likely – to load templates from the server via AJAX calls. In short there are options The above shows off some of the basics, but there’s much for functionality available in the template engine. Check the documentation link for more information and links to additional examples. The plug-in download also comes with a number of examples that demonstrate functionality. jQuery templates will become a native component in jQuery Core 1.5, so it’s definitely worthwhile checking out the engine today and get familiar with this interface. As much as I’m stoked about templating becoming part of the jQuery core because it’s such an integral part of many applications, there are also a couple shortcomings in the current incarnation: Lack of Error Handling Currently if you embed an expression that is invalid it’s simply not rendered. There’s no error rendered into the template nor do the various  template functions throw errors which leaves finding of bugs as a runtime exercise. I would like some mechanism – optional if possible – to be able to get error info of what is failing in a template when it’s rendered. No String Output Templates are always rendered into a jQuery matched set and there’s no way that I can see to directly render to a string. String output can be useful for debugging as well as opening up templating for creating non-HTML string output. Limited JavaScript Access Unlike John Resig’s original MicroTemplating Engine which was entirely based on JavaScript code generation these templates are limited to a few structured commands that can ‘execute’. There’s no code execution inside of script code which means you’re limited to calling expressions available in global objects or the data item passed in. This may or may not be a big deal depending on the complexity of your template logic. Error handling has been discussed quite a bit and it’s likely there will be some solution to that particualar issue by the time jQuery templates ship. The others are relatively minor issues but something to think about anyway. jQuery Data Link http://api.jquery.com/category/plugins/data-link/ jQuery Data Link provides the ability to do two-way data binding between input controls and an underlying object’s properties. The typical scenario is linking a textbox to a property of an object and have the object updated when the text in the textbox is changed and have the textbox change when the value in the object or the entire object changes. The plug-in also supports converter functions that can be applied to provide the conversion logic from string to some other value typically necessary for mapping things like textbox string input to say a number property and potentially applying additional formatting and calculations. In theory this sounds great, however in reality this plug-in has some serious usability issues. Using the plug-in you can do things like the following to bind data: person = { firstName: "rick", lastName: "strahl"}; $(document).ready( function() { // provide for two-way linking of inputs $("form").link(person); // bind to non-input elements explicitly $("#objFirst").link(person, { firstName: { name: "objFirst", convertBack: function (value, source, target) { $(target).text(value); } } }); $("#objLast").link(person, { lastName: { name: "objLast", convertBack: function (value, source, target) { $(target).text(value); } } }); }); This code hooks up two-way linking between a couple of textboxes on the page and the person object. The first line in the .ready() handler provides mapping of object to form field with the same field names as properties on the object. Note that .link() does NOT bind items into the textboxes when you call .link() – changes are mapped only when values change and you move out of the field. Strike one. The two following commands allow manual binding of values to specific DOM elements which is effectively a one-way bind. You specify the object and a then an explicit mapping where name is an ID in the document. The converter is required to explicitly assign the value to the element. Strike two. You can also detect changes to the underlying object and cause updates to the input elements bound. Unfortunately the syntax to do this is not very natural as you have to rely on the jQuery data object. To update an object’s properties and get change notification looks like this: function updateFirstName() { $(person).data("firstName", person.firstName + " (code updated)"); } This works fine in causing any linked fields to be updated. In the bindings above both the firstName input field and objFirst DOM element gets updated. But the syntax requires you to use a jQuery .data() call for each property change to ensure that the changes are tracked properly. Really? Sure you’re binding through multiple layers of abstraction now but how is that better than just manually assigning values? The code savings (if any) are going to be minimal. As much as I would like to have a WPF/Silverlight/Observable-like binding mechanism in client script, this plug-in doesn’t help much towards that goal in its current incarnation. While you can bind values, the ‘binder’ is too limited to be really useful. If initial values can’t be assigned from the mappings you’re going to end up duplicating work loading the data using some other mechanism. There’s no easy way to re-bind data with a different object altogether since updates trigger only through the .data members. Finally, any non-input elements have to be bound via code that’s fairly verbose and frankly may be more voluminous than what you might write by hand for manual binding and unbinding. Two way binding can be very useful but it has to be easy and most importantly natural. If it’s more work to hook up a binding than writing a couple of lines to do binding/unbinding this sort of thing helps very little in most scenarios. In talking to some of the developers the feature set for Data Link is not complete and they are still soliciting input for features and functionality. If you have ideas on how you want this feature to be more useful get involved and post your recommendations. As it stands, it looks to me like this component needs a lot of love to become useful. For this component to really provide value, bindings need to be able to be refreshed easily and work at the object level, not just the property level. It seems to me we would be much better served by a model binder object that can perform these binding/unbinding tasks in bulk rather than a tool where each link has to be mapped first. I also find the choice of creating a jQuery plug-in questionable – it seems a standalone object – albeit one that relies on the jQuery library – would provide a more intuitive interface than the current forcing of options onto a plug-in style interface. Out of the three Microsoft created components this is by far the least useful and least polished implementation at this point. jQuery Globalization http://github.com/jquery/jquery-global Globalization in JavaScript applications often gets short shrift and part of the reason for this is that natively in JavaScript there’s little support for formatting and parsing of numbers and dates. There are a number of JavaScript libraries out there that provide some support for globalization, but most are limited to a particular portion of globalization. As .NET developers we’re fairly spoiled by the richness of APIs provided in the framework and when dealing with client development one really notices the lack of these features. While you may not necessarily need to localize your application the globalization plug-in also helps with some basic tasks for non-localized applications: Dealing with formatting and parsing of dates and time values. Dates in particular are problematic in JavaScript as there are no formatters whatsoever except the .toString() method which outputs a verbose and next to useless long string. With the globalization plug-in you get a good chunk of the formatting and parsing functionality that the .NET framework provides on the server. You can write code like the following for example to format numbers and dates: var date = new Date(); var output = $.format(date, "MMM. dd, yy") + "\r\n" + $.format(date, "d") + "\r\n" + // 10/25/2010 $.format(1222.32213, "N2") + "\r\n" + $.format(1222.33, "c") + "\r\n"; alert(output); This becomes even more useful if you combine it with templates which can also include any JavaScript expressions. Assuming the globalization plug-in is loaded you can create template expressions that use the $.format function. Here’s the template I used earlier for the stock quote again with a couple of formats applied: <script id="stockTemplate" type="text/x-jquery-tmpl"> <div id="divStockQuote" class="errordisplay" style="width: 500px;"> <div class="label">Company:</div><div><b>${Company}(${Symbol})</b></div> <div class="label">Last Price:</div> <div>${$.format(LastPrice,"N2")}</div> <div class="label">Net Change:</div><div> {{if NetChange > 0}} <b style="color:green" >${NetChange}</b> {{else}} <b style="color:red" >${NetChange}</b> {{/if}} </div> <div class="label">Last Update:</div> <div>${$.format(LastQuoteTime,"MMM dd, yyyy")}</div> </div> </script> There are also parsing methods that can parse dates and numbers from strings into numbers easily: alert($.parseDate("25.10.2010")); alert($.parseInt("12.222")); // de-DE uses . for thousands separators As you can see culture specific options are taken into account when parsing. The globalization plugin provides rich support for a variety of locales: Get a list of all available cultures Query cultures for culture items (like currency symbol, separators etc.) Localized string names for all calendar related items (days of week, months) Generated off of .NET’s supported locales In short you get much of the same functionality that you already might be using in .NET on the server side. The plugin includes a huge number of locales and an Globalization.all.min.js file that contains the text defaults for each of these locales as well as small locale specific script files that define each of the locale specific settings. It’s highly recommended that you NOT use the huge globalization file that includes all locales, but rather add script references to only those languages you explicitly care about. Overall this plug-in is a welcome helper. Even if you use it with a single locale (like en-US) and do no other localization, you’ll gain solid support for number and date formatting which is a vital feature of many applications. Changes for Microsoft It’s good to see Microsoft coming out of its shell and away from the ‘not-built-here’ mentality that has been so pervasive in the past. It’s especially good to see it applied to jQuery – a technology that has stood in drastic contrast to Microsoft’s own internal efforts in terms of design, usage model and… popularity. It’s great to see that Microsoft is paying attention to what customers prefer to use and supporting the customer sentiment – even if it meant drastically changing course of policy and moving into a more open and sharing environment in the process. The additional jQuery support that has been introduced in the last two years certainly has made lives easier for many developers on the ASP.NET platform. It’s also nice to see Microsoft submitting proposals through the standard jQuery process of plug-ins and getting accepted for various very useful projects. Certainly the jQuery Templates plug-in is going to be very useful to many especially since it will be baked into the jQuery core in jQuery 1.5. I hope we see more of this type of involvement from Microsoft in the future. Kudos!© Rick Strahl, West Wind Technologies, 2005-2010Posted in jQuery  ASP.NET  

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  • #1 O’Reilly eBook for 2010

    - by Jan Goyvaerts
    The year-end issue of O’Reilly’s author newsletter discussed the trends O’Reilly has been seeing the past few years, and their predictions for 2011. The key trend is that digital is now more than ever poised to take over print: Our digitally distributed products have grown from 18.36% of our publishing mix in 2009 to 28.09% of our mix in 2010. What is more impressive is that our digitally distributed products have produced more than double the revenue that has been lost with the decline of print. I think this is important because some say that digital cannibalizes print products. Our data indicates the contrary, as print is declining much more slowly than digital is growing. I think we may be seeing developers purchasing a print book, and then purchasing the electronic editions to search and copying code from, as the incremental cost for digital is more than reasonable. My own book seems to be leading this trend. Thanks to everyone who purchased it! And the five bestselling O’Reilly ebook products for 2010: 1) Regular Expressions Cookbook, 2) jQuery Cookbook, 3) Learning Python, 4) HTML5: Up and Running, and 5) JavaScript Cookbook. I think it’s interesting that the top five ebooks are code-intensive books. They’re great products for search and code reuse. It’s also interesting that none of the top 5 ebooks made the top 5 of print books.

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  • Scheme Formatting Help

    - by Logan
    I've been working on a project for school that takes functions from a class file and turns them into object/classes. The assignment is all about object oriented programming in scheme. My problem however is that my code doesn't format right. The output it gives me whenever I give it a file to pass in wraps the methods of the class in a list, making it so that the class never really gets declared. I can't for the life of me figure out how to get the parenthesis wrapping the method list to remove. I would really appreciate any help. Below is the code and the class file. ;;;; PART1 --- A super-easy set of classes. Just models points and lines. Tests all of the ;; basics of class behavior without touching on anything particularly complex. (class pointInstance (parent:) (constructor_args:) (ivars: (myx 1) (myy 2)) (methods: (getx () myx) (gety () myy) (setx (x) (set! myx x)) (show () (begin (display "[") (display myx) (display ",") (display myy) (display "]"))) )) (require (lib "trace.ss")) ;; Continue reading until you hit the end of the file, all the while ;; building a list with the contents (define load-file (lambda (port) (let ((rec (read port))) (if (eof-object? rec) '() (cons rec (load-file port)))))) ;; Open a port based on a file name using open-input-file (define (load fname) (let ((fport (open-input-file fname))) (load-file fport))) ;(define lis (load "C:\\Users\\Logan\\Desktop\\simpletest.txt")) ;(define lis (load "C:\\Users\\Logan\\Desktop\\complextest.txt")) (define lis (load "C:\\Users\\Logan\\Desktop\\pointinstance.txt")) ;(display (cdaddr (cdddar lis))) (define makeMethodList (lambda (listToMake retList) ;(display listToMake) (cond [(null? listToMake) retList ;(display "The list passed in to parse was null") ] [else (makeMethodList (cdr listToMake) (append retList (list (getMethodLine listToMake)))) ] ) )) ;(trace makeMethodList) ;this works provided you just pass in the function line (define getMethodLine (lambda (functionList) `((eq? (car msg) ,(caar functionList)) ,(caddar functionList)))) (define load-classes (lambda paramList (cond [(null? paramList) (display "Your parameters are null, man.")] [(null? (car paramList))(display "Done creating class definitions.")] [(not (null? (car paramList))) (begin (let* ((className (cadaar paramList)) (classInstanceVars (cdaddr (cddaar paramList))) (classMethodList (cdr (cadddr (cddaar paramList)))) (desiredMethodList (makeMethodList classMethodList '())) ) ;(display "Classname: ") ;(display className) ;(newline)(newline) ;(display "Class Instance Vars: ") ;(display classInstanceVars) ;(newline)(newline) ;(display "Class Method List: ") ;(display classMethodList) ;(newline) ;(display "Desired Method List: ") ;(display desiredMethodList)) ;(newline)(newline) ;---------------------------------------------------- ;do not delete the below code!` `(define ,className (let ,classInstanceVars (lambda msg ;return the function list here (cond ,(makeMethodList classMethodList '()))) )) ;--------------------------------------------------- ))] ) )) (load-classes lis) ;(load-classes lis) ;(load-classes-helper lis) ;(load-classes "simpletest.txt") ;(load-classes "complextest.txt") ;method list ;(display (cdr (cadddr (cddaar <class>))))

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  • New Regular Expression Features in Java 8

    - by Jan Goyvaerts
    Java 8 brings a few changes to Java’s regular expression syntax to make it more consistent with Perl 5.14 and later in matching horizontal and vertical whitespace. \h is a new feature. It is a shorthand character class that matches any horizontal whitespace character as defined in the Unicode standard. In Java 4 to 7 \v is a character escape that matches only the vertical tab character. In Java 8 \v is a shorthand character class that matches any vertical whitespace, including the vertical tab. When upgrading to Java 8, make sure that any regexes that use \v still do what you want. Use \x0B or \cK to match just the vertical tab in any version of Java. \R is also a new feature. It matches any line break as defined by the Unicode standard. Windows-style CRLF pairs are always matched as a whole. So \R matches \r\n while \R\R fails to match \r\n. \R is equivalent to (?\r\n|[\n\cK\f\r\u0085\u2028\u2029]) with an atomic group that prevents it from matching only the CR in a CRLF pair. Oracle’s documentation for the Pattern class omits the atomic group when explaining \R, which is incorrect. You cannot use \R inside a character class. RegexBuddy and RegexMagic have been updated to support Java 8. Java 4, 5, 6, and 7 are still supported. When you upgrade to Java 8 you can compare or convert your regular expressions between Java 8 and the Java version you were using previously.

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  • PerlRegEx vs RegularExpressionsCore Delphi Units

    - by Jan Goyvaerts
    The RegularExpressionsCore unit that is part of Delphi XE is based on the latest class-based PerlRegEx unit that I developed. Embarcadero only made a few changes to the unit. These changes are insignificant enough that code written for earlier versions of Delphi using the class-based PerlRegEx unit will work just the same with Delphi XE. The unit was renamed from PerlRegEx to RegularExpressionsCore. When migrating your code to Delphi XE, you can choose whether you want to use the new RegularExpressionsCore unit or continue using the PerlRegEx unit in your application. All you need to change is which unit you add to the uses clause in your own units. Indentation and line breaks in the code were changed to match the style used in the Delphi RTL and VCL code. This does not change the code, but makes it harder to diff the two units. Literal strings in the unit were separated into their own unit called RegularExpressionsConsts. These strings are only used for error messages that indicate bugs in your code. If your code uses TPerlRegEx correctly then the user should not see any of these strings. My code uses assertions to check for out of bounds parameters, while Embarcadero uses exceptions. Again, if you use TPerlRegEx correctly, you should never get any assertions or exceptions. The Compile method raises an exception if the regular expression is invalid in both my original TPerlRegEx component and Embarcadero’s version. If your code allows the user to provide the regular expression, you should explicitly call Compile and catch any exceptions it raises so you can tell the user there is a problem with the regular expression. Even with user-provided regular expressions, you shouldn’t get any other assertions or exceptions if your code is correct. Note that Embarcadero owns all the rights to their RegularExpressionsCore unit. Like all the other RTL and VCL units, this unit cannot be distributed by myself or anyone other than Embarcadero. I do retain the rights to my original PerlRegEx unit which I will continue to make available for those using older versions of Delphi.

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  • How do I defer execution of some Ruby code until later and run it on demand in this scenario?

    - by Kyle Kaitan
    I've got some code that looks like the following. First, there's a simple Parser class for parsing command-line arguments with options. class Parser def initialize(&b); ...; end # Create new parser. def parse(args = ARGV); ...; end # Consume command-line args. def opt(...); ...; end # Declare supported option. def die(...); ...; end # Validation handler. end Then I have my own Parsers module which holds some metadata about parsers that I want to track. module Parsers ParserMap = {} def self.make_parser(kind, desc, &b) b ||= lambda {} module_eval { ParserMap[kind] = {:desc => "", :validation => lambda {} } ParserMap[kind][:desc] = desc # Create new parser identified by `<Kind>Parser`. Making a Parser is very # expensive, so we defer its creation until it's actually needed later # by wrapping it in a lambda and calling it when we actually need it. const_set(name_for_parser(kind), lambda { Parser.new(&b) }) } end # ... end Now when you want to add a new parser, you can call make_parser like so: make_parser :db, "login to database" do # Options that this parser knows how to parse. opt :verbose, "be verbose with output messages" opt :uid, "user id" opt :pwd, "password" end Cool. But there's a problem. We want to optionally associate validation with each parser, so that we can write something like: validation = lambda { |parser, opts| parser.die unless opts[:uid] && opts[:pwd] # Must provide login. } The interface contract with Parser says that we can't do any validation until after Parser#parse has been called. So, we want to do the following: Associate an optional block with every Parser we make with make_parser. We also want to be able to run this block, ideally as a new method called Parser#validate. But any on-demand method is equally suitable. How do we do that?

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  • Using Lambdas for return values in Rhino.Mocks

    - by PSteele
    In a recent StackOverflow question, someone showed some sample code they’d like to be able to use.  The particular syntax they used isn’t supported by Rhino.Mocks, but it was an interesting idea that I thought could be easily implemented with an extension method. Background When stubbing a method return value, Rhino.Mocks supports the following syntax: dependency.Stub(s => s.GetSomething()).Return(new Order()); The method signature is generic and therefore you get compile-time type checking that the object you’re returning matches the return value defined by the “GetSomething” method. You could also have Rhino.Mocks execute arbitrary code using the “Do” method: dependency.Stub(s => s.GetSomething()).Do((Func<Order>) (() => new Order())); This requires the cast though.  It works, but isn’t as clean as the original poster wanted.  They showed a simple example of something they’d like to see: dependency.Stub(s => s.GetSomething()).Return(() => new Order()); Very clean, simple and no casting required.  While Rhino.Mocks doesn’t support this syntax, it’s easy to add it via an extension method. The Rhino.Mocks “Stub” method returns an IMethodOptions<T>.  We just need to accept a Func<T> and use that as the return value.  At first, this would seem straightforward: public static IMethodOptions<T> Return<T>(this IMethodOptions<T> opts, Func<T> factory) { opts.Return(factory()); return opts; } And this would work and would provide the syntax the user was looking for.  But the problem with this is that you loose the late-bound semantics of a lambda.  The Func<T> is executed immediately and stored as the return value.  At the point you’re setting up your mocks and stubs (the “Arrange” part of “Arrange, Act, Assert”), you may not want the lambda executing – you probably want it delayed until the method is actually executed and Rhino.Mocks plugs in your return value. So let’s make a few small tweaks: public static IMethodOptions<T> Return<T>(this IMethodOptions<T> opts, Func<T> factory) { opts.Return(default(T)); // required for Rhino.Mocks on non-void methods opts.WhenCalled(mi => mi.ReturnValue = factory()); return opts; } As you can see, we still need to set up some kind of return value or Rhino.Mocks will complain as soon as it intercepts a call to our stubbed method.  We use the “WhenCalled” method to set the return value equal to the execution of our lambda.  This gives us the delayed execution we’re looking for and a nice syntax for lambda-based return values in Rhino.Mocks. Technorati Tags: .NET,Rhino.Mocks,Mocking,Extension Methods

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  • Help with dynamic-wind and call/cc

    - by josh
    I am having some trouble understanding the behavior of the following Scheme program: (define c (dynamic-wind (lambda () (display 'IN)(newline)) (lambda () (call/cc (lambda (k) (display 'X)(newline) k))) (lambda () (display 'OUT)(newline)))) As I understand, c will be bound to the continution created right before "(display 'X)". But using c seems to modify itself! The define above prints (as I expected) IN, X and OUT: IN X OUT And it is a procedure: #;2> c #<procedure (a9869 . results1678)> Now, I would expect that when it is called again, X would be printed, and it is not! #;3> (c) IN OUT And now c is not a procedure anymore, and a second invokation of c won't work! #;4> c ;; the REPL doesn't answer this, so there are no values returned #;5> (c) Error: call of non-procedure: #<unspecified> Call history: <syntax> (c) <eval> (c) <-- I was expecting that each invokation to (c) would do the same thing -- print IN, X, and OUT. What am I missing?

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  • .NET RegEx - First N chars of First M lines

    - by George
    Hello! I want 4 general RegEx expressions for the following 4 basic cases: Up to A chars starting after B chars from start of line on up to C lines starting after D lines from start of file Up to A chars starting after B chars from start of line on up to C lines occurring before D lines from end of file Up to A chars starting before B chars from end of line on up to C lines starting after D lines from start of file Up to A chars starting before B chars from end of line on up to C lines starting before D lines from end of file These would allow to select arbitrary text blocks anywhere in the file. So far I have managed to come up with cases that only work for lines and chars separately: (?<=(?m:^[^\r]{N}))[^\r]{1,M} = UP TO M chars OF EVERY LINE, AFTER FIRST N chars [^\r]{1,M}(?=(?m:.{N}\r$)) = UP TO M chars OF EVERY LINE, BEFORE LAST N chars The above 2 expressions are for chars, and they return MANY matches (one for each line). (?<=(\A([^\r]*\r\n){N}))(?m:\n*[^\r]*\r$){1,M} = UP TO M lines AFTER FIRST N lines (((?=\r?)\n[^\r]*\r)|((?=\r?)\n[^\r]+\r?)){1,M}(?=((\n[^\r]*\r)|(\n[^\r]+\r?)){N}\Z) = UP TO M lines BEFORE LAST N lines from end These 2 expressions are equivalents for the lines, but they always return just ONE match. The task is to combine these expressions to allow for scenarios 1-4. Anyone can help? Note that the case in the title of the question, is just a subclass of scenario #1, where both B = 0 and D = 0. EXAMPLE: SOURCE: line1 blah 1 line2 blah 2 line3 blah 3 line4 blah 4 line5 blah 5 line6 blah 6 DESIRED RESULT: Characters 3-6 of lines 3-5: A total of 3 matches: <match>ne3 </match> <match>ne4 </match> <match>ne5 </match>

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  • CarrierWave and nested forms saving empty image object if photo :title is included in form

    - by Wasabi Developer
    I'm after some advice in regards to handling nested form data and I would be ever so grateful for any insights. The trouble is I'm not 100% sure why I require the following code in my model accepts_nested_attributes_for :holiday_image, allow_destroy: true, :reject_if => lambda { |a| a[:title].blank? } If I don't understand why I require to tact on on my accepts_nested_attributes_for association: :reject_if => lambda { |a| a[:title].blank? } If I remove this :reject_if lambda, it will save a blank holiday photo object in the database. I presume because it takes the :title field from the form as an empty string? I guess my question is, am I doing this right or is there a better way of this this within nested forms if I want to extend my HolidayImage model to include more strings like description, notes? Sorry If I can't be more succinct. My simple holiday app. # holiday.rb class Holiday < ActiveRecord::Base has_many :holiday_image accepts_nested_attributes_for :holiday_image, allow_destroy: true, :reject_if => lambda { |a| a[:title].blank? } attr_accessible :name, :content, :holiday_image_attributes end I'm using CarrierWave for image uploads. # holiday_image.rb class HolidayImage < ActiveRecord::Base belongs_to :holiday attr_accessible :holiday_id, :image, :title mount_uploader :image, ImageUploader end Inside my _form partial there is a field_for block <h3>Photo gallery</h3> <%= f.fields_for :holiday_image do |holiday_image| %> <% if holiday_image.object.new_record? %> <%= holiday_image.label :title, "Image Title" %> <%= holiday_image.text_field :title %> <%= holiday_image.file_field :image %> <% else %> Title: <%= holiday_image.object.title %> <%= image_tag(holiday_image.object.image.url(:thumb)) %> Tick to delete: <%= holiday_image.check_box :_destroy %> <% end %> Thanks again for your patience.

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  • do the Python libraries have a natural dependence on the global namespace?

    - by msw
    I first ran into this when trying to determine the relative performance of two generators: t = timeit.repeat('g.get()', setup='g = my_generator()') So I dug into the timeit module and found that the setup and statement are evaluated with their own private, initially empty namespaces so naturally the binding of g never becomes accessible to the g.get() statement. The obvious solution is to wrap them into a class, thus adding to the global namespace. I bumped into this again when attempting, in another project, to use the multiprocessing module to divide a task among workers. I even bundled everything nicely into a class but unfortunately the call pool.apply_async(runmc, arg) fails with a PicklingError because buried inside the work object that runmc instantiates is (effectively) an assignment: self.predicate = lambda x, y: x > y so the whole object can't be (understandably) pickled and whereas: def foo(x, y): return x > y pickle.dumps(foo) is fine, the sequence bar = lambda x, y: x > y yields True from callable(bar) and from type(bar), but it Can't pickle <function <lambda> at 0xb759b764>: it's not found as __main__.<lambda>. I've given only code fragments because I can easily fix these cases by merely pulling them out into module or object level defs. The bug here appears to be in my understanding of the semantics of namespace use in general. If the nature of the language requires that I create more def statements I'll happily do so; I fear that I'm missing an essential concept though. Why is there such a strong reliance on the global namespace? Or, what am I failing to understand? Namespaces are one honking great idea -- let's do more of those!

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  • using Python reduce over a list of pairs

    - by user248237
    I'm trying to pair together a bunch of elements in a list to create a final object, in a way that's analogous to making a sum of objects. I'm trying to use a simple variation on reduce where you consider a list of pairs rather than a flat list to do this. I want to do something along the lines of: nums = [1, 2, 3] reduce(lambda x, y: x + y, nums) except I'd like to add additional information to the sum that is specific to each element in the list of numbers nums. For example for each pair (a,b) in the list, run the sum as (a+b): nums = [(1, 0), (2, 5), (3, 10)] reduce(lambda x, y: (x[0]+x[1]) + (y[0]+y[1]), nums) This does not work: >>> reduce(lambda x, y: (x[0]+x[1]) + (y[0]+y[1]), nums) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "<stdin>", line 1, in <lambda> TypeError: 'int' object is unsubscriptable Why does it not work? I know I can encode nums as a flat list - that is not the point - I just want to be able to create a reduce operation that can iterate over a list of pairs, or over two lists of the same length simultaneously and pool information from both lists. thanks.

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  • Scheme Function to reverse elements of list of 2-list

    - by sudhirc
    This is an exercise from EOPL. Procedure (invert lst) takes lst which is a list of 2-lists and returns a list with each 2-list reversed. (define invert (lambda (lst) (cond((null? lst ) '()) ((= 2 (rtn-len (car lst))) ( cons(swap-elem (car lst)) (invert (cdr lst)))) ("List is not a 2-List")))) ;; Auxiliry Procedure swap-elements of 2 element list (define swap-elem (lambda (lst) (cons (car (cdr lst)) (car lst)))) ;; returns lengh of the list by calling (define rtn-len (lambda (lst) (calc-len lst 0))) ;; calculate length of the list (define calc-len (lambda (lst n) (if (null? lst) n (calc-len (cdr lst) (+ n 1))))) This seems to work however looks very verbose. Can this be shortened or written in more elegant way ? How I can halt the processing in any of the individual element is not a 2-list? At the moment execution proceed to next member and replacing current member with "List is not a 2-List" if current member is not a 2-list.

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  • Creating a sort function for a generic list

    - by Andrey
    I have a method for sorting generic lists by the object fields: public static IQueryable<T> SortTable<T>(IQueryable<T> q, string sortfield, bool ascending) { var p = Expression.Parameter(typeof(T), "p"); if (typeof(T).GetProperty(sortfield).PropertyType == typeof(int?)) { var x = Expression.Lambda<Func<T, int?>>(Expression.Property(p, sortfield), p); if (ascending) q = q.OrderBy(x); else q = q.OrderByDescending(x); } else if (typeof(T).GetProperty(sortfield).PropertyType == typeof(int)) { var x = Expression.Lambda<Func<T, int>>(Expression.Property(p, sortfield), p); if (ascending) q = q.OrderBy(x); else q = q.OrderByDescending(x); } else if (typeof(T).GetProperty(sortfield).PropertyType == typeof(DateTime)) { var x = Expression.Lambda<Func<T, DateTime>>(Expression.Property(p, sortfield), p); if (ascending) q = q.OrderBy(x); else q = q.OrderByDescending(x); } // many more for every type return q; } Is there any way I can collapse those ifs to a single generic statement? The main problem is that for the part Expression.Lambda<Func<T, int>> I am not sure how to write it generically.

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  • Parallelism in .NET – Part 14, The Different Forms of Task

    - by Reed
    Before discussing Task creation and actual usage in concurrent environments, I will briefly expand upon my introduction of the Task class and provide a short explanation of the distinct forms of Task.  The Task Parallel Library includes four distinct, though related, variations on the Task class. In my introduction to the Task class, I focused on the most basic version of Task.  This version of Task, the standard Task class, is most often used with an Action delegate.  This allows you to implement for each task within the task decomposition as a single delegate. Typically, when using the new threading constructs in .NET 4 and the Task Parallel Library, we use lambda expressions to define anonymous methods.  The advantage of using a lambda expression is that it allows the Action delegate to directly use variables in the calling scope.  This eliminates the need to make separate Task classes for Action<T>, Action<T1,T2>, and all of the other Action<…> delegate types.  As an example, suppose we wanted to make a Task to handle the ”Show Splash” task from our earlier decomposition.  Even if this task required parameters, such as a message to display, we could still use an Action delegate specified via a lambda: // Store this as a local variable string messageForSplashScreen = GetSplashScreenMessage(); // Create our task Task showSplashTask = new Task( () => { // We can use variables in our outer scope, // as well as methods scoped to our class! this.DisplaySplashScreen(messageForSplashScreen); }); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This provides a huge amount of flexibility.  We can use this single form of task for any task which performs an operation, provided the only information we need to track is whether the task has completed successfully or not.  This leads to my first observation: Use a Task with a System.Action delegate for any task for which no result is generated. This observation leads to an obvious corollary: we also need a way to define a task which generates a result.  The Task Parallel Library provides this via the Task<TResult> class. Task<TResult> subclasses the standard Task class, providing one additional feature – the ability to return a value back to the user of the task.  This is done by switching from providing an Action delegate to providing a Func<TResult> delegate.  If we decompose our problem, and we realize we have one task where its result is required by a future operation, this can be handled via Task<TResult>.  For example, suppose we want to make a task for our “Check for Update” task, we could do: Task<bool> checkForUpdateTask = new Task<bool>( () => { return this.CheckWebsiteForUpdate(); }); Later, we would start this task, and perform some other work.  At any point in the future, we could get the value from the Task<TResult>.Result property, which will cause our thread to block until the task has finished processing: // This uses Task<bool> checkForUpdateTask generated above... // Start the task, typically on a background thread checkForUpdateTask.Start(); // Do some other work on our current thread this.DoSomeWork(); // Discover, from our background task, whether an update is available // This will block until our task completes bool updateAvailable = checkForUpdateTask.Result; This leads me to my second observation: Use a Task<TResult> with a System.Func<TResult> delegate for any task which generates a result. Task and Task<TResult> provide a much cleaner alternative to the previous Asynchronous Programming design patterns in the .NET framework.  Instead of trying to implement IAsyncResult, and providing BeginXXX() and EndXXX() methods, implementing an asynchronous programming API can be as simple as creating a method that returns a Task or Task<TResult>.  The client side of the pattern also is dramatically simplified – the client can call a method, then either choose to call task.Wait() or use task.Result when it needs to wait for the operation’s completion. While this provides a much cleaner model for future APIs, there is quite a bit of infrastructure built around the current Asynchronous Programming design patterns.  In order to provide a model to work with existing APIs, two other forms of Task exist.  There is a constructor for Task which takes an Action<Object> and a state parameter.  In addition, there is a constructor for creating a Task<TResult> which takes a Func<Object, TResult> as well as a state parameter.  When using these constructors, the state parameter is stored in the Task.AsyncState property. While these two overloads exist, and are usable directly, I strongly recommend avoiding this for new development.  The two forms of Task which take an object state parameter exist primarily for interoperability with traditional .NET Asynchronous Programming methodologies.  Using lambda expressions to capture variables from the scope of the creator is a much cleaner approach than using the untyped state parameters, since lambda expressions provide full type safety without introducing new variables.

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  • Using delegates in C# (Part 2)

    - by rajbk
    Part 1 of this post can be read here. We are now about to see the different syntaxes for invoking a delegate and some c# syntactic sugar which allows you to code faster. We have the following console application. 1: public delegate double Operation(double x, double y); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: Operation op1 = new Operation(Division); 9: double result = op1.Invoke(10, 5); 10: 11: Console.WriteLine(result); 12: Console.ReadLine(); 13: } 14: 15: static double Division(double x, double y) { 16: return x / y; 17: } 18: } Line 1 defines a delegate type called Operation with input parameters (double x, double y) and a return type of double. On Line 8, we create an instance of this delegate and set the target to be a static method called Division (Line 15) On Line 9, we invoke the delegate (one entry in the invocation list). The program outputs 5 when run. The language provides shortcuts for creating a delegate and invoking it (see line 9 and 11). Line 9 is a syntactical shortcut for creating an instance of the Delegate. The C# compiler will infer on its own what the delegate type is and produces intermediate language that creates a new instance of that delegate. Line 11 uses a a syntactical shortcut for invoking the delegate by removing the Invoke method. The compiler sees the line and generates intermediate language which invokes the delegate. When this code is compiled, the generated IL will look exactly like the IL of the compiled code above. 1: public delegate double Operation(double x, double y); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: //shortcut constructor syntax 9: Operation op1 = Division; 10: //shortcut invoke syntax 11: double result = op1(10, 2); 12: 13: Console.WriteLine(result); 14: Console.ReadLine(); 15: } 16: 17: static double Division(double x, double y) { 18: return x / y; 19: } 20: } C# 2.0 introduced Anonymous Methods. Anonymous methods avoid the need to create a separate method that contains the same signature as the delegate type. Instead you write the method body in-line. There is an interesting fact about Anonymous methods and closures which won’t be covered here. Use your favorite search engine ;-)We rewrite our code to use anonymous methods (see line 9): 1: public delegate double Operation(double x, double y); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: //Anonymous method 9: Operation op1 = delegate(double x, double y) { 10: return x / y; 11: }; 12: double result = op1(10, 2); 13: 14: Console.WriteLine(result); 15: Console.ReadLine(); 16: } 17: 18: static double Division(double x, double y) { 19: return x / y; 20: } 21: } We could rewrite our delegate to be of a generic type like so (see line 2 and line 9). You will see why soon. 1: //Generic delegate 2: public delegate T Operation<T>(T x, T y); 3:  4: public class Program 5: { 6: [STAThread] 7: static void Main(string[] args) 8: { 9: Operation<double> op1 = delegate(double x, double y) { 10: return x / y; 11: }; 12: double result = op1(10, 2); 13: 14: Console.WriteLine(result); 15: Console.ReadLine(); 16: } 17: 18: static double Division(double x, double y) { 19: return x / y; 20: } 21: } The .NET 3.5 framework introduced a whole set of predefined delegates for us including public delegate TResult Func<T1, T2, TResult>(T1 arg1, T2 arg2); Our code can be modified to use this delegate instead of the one we declared. Our delegate declaration has been removed and line 7 has been changed to use the Func delegate type. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: //Func is a delegate defined in the .NET 3.5 framework 7: Func<double, double, double> op1 = delegate (double x, double y) { 8: return x / y; 9: }; 10: double result = op1(10, 2); 11: 12: Console.WriteLine(result); 13: Console.ReadLine(); 14: } 15: 16: static double Division(double x, double y) { 17: return x / y; 18: } 19: } .NET 3.5 also introduced lambda expressions. A lambda expression is an anonymous function that can contain expressions and statements, and can be used to create delegates or expression tree types. We change our code to use lambda expressions. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: //lambda expression 7: Func<double, double, double> op1 = (x, y) => x / y; 8: double result = op1(10, 2); 9: 10: Console.WriteLine(result); 11: Console.ReadLine(); 12: } 13: 14: static double Division(double x, double y) { 15: return x / y; 16: } 17: } C# 3.0 introduced the keyword var (implicitly typed local variable) where the type of the variable is inferred based on the type of the associated initializer expression. We can rewrite our code to use var as shown below (line 7).  The implicitly typed local variable op1 is inferred to be a delegate of type Func<double, double, double> at compile time. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: //implicitly typed local variable 7: var op1 = (x, y) => x / y; 8: double result = op1(10, 2); 9: 10: Console.WriteLine(result); 11: Console.ReadLine(); 12: } 13: 14: static double Division(double x, double y) { 15: return x / y; 16: } 17: } You have seen how we can write code in fewer lines by using a combination of the Func delegate type, implicitly typed local variables and lambda expressions.

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  • New regular expression features in PCRE 8.34 and 8.35

    - by Jan Goyvaerts
    PCRE 8.34 adds some new regex features and changes the behavior of a few to make it better compatible with the latest versions of Perl. There are no changes to the regex syntax in PCRE 8.35. \o{377} is now an octal escape just like \377. This syntax was first introduced in Perl 5.12. It avoids any confusion between octal escapes and backreferences. It also allows octal numbers beyond 377 to be used. E.g. \o{400} is the same as \x{100}. If you have any reason to use octal escapes instead of hexadecimal escapes then you should definitely use the new syntax. Because of this change, \o is now an error when it doesn’t form a valid octal escape. Previously \o was a literal o and \o{377} was a sequence of 337 o‘s. In free-spacing mode, whitespace between a quantifier and the ? that makes it lazy or the + that makes it possessive is now ignored. In Perl this has always been the case. In PCRE 8.33 and prior, whitespace ended a quantifier and any following ? or + was seen as a second quantifier and thus an error. The shorthand \s now matches the vertical tab character in addition to the other whitespace characters it previously matched. Perl 5.18 made the same change. Many other regex flavors have always included the vertical tab in \s, just like POSIX has always included it in [[:space:]]. Names of capturing groups are no longer allowed to start with a digit. This has always been the case in Perl since named groups were added to Perl 5.10. PCRE 8.33 and prior even allowed group names to consist entirely of digits. [[:<:]] and [[::]] are now treated as POSIX-style word boundaries. They match at the start and the end of a word. Though they use similar syntax, these have nothing to do with POSIX character classes and cannot be used inside character classes. Perl does not support POSIX word boundaries. The same changes affect PHP 5.5.10 (and later) and R 3.0.3 (and later) as they have been updated to use PCRE 8.34. RegexBuddy and RegexMagic have been updated to support the latest versions of PCRE, PHP, and R. Older versions that were previously supported are still supported, so you can compare or convert your regular expressions between the latest versions of PCRE, PHP, and R and whichever version you were using previously.

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  • New TPerlRegEx Compatible with Delphi XE

    - by Jan Goyvaerts
    The new RegularExpressionsCore unit in Delphi XE is based on the PerlRegEx unit that I wrote many years ago. Since I donated full rights to a copy rather than full rights to the original, I can continue to make my version of TPerlRegEx available to people using older versions of Delphi. I did make a few changes to the code to modernize it a bit prior to donating a copy to Embarcadero. The latest TPerlRegEx includes those changes. This allows you to use the same regex-based code using the RegularExpressionsCore unit in Delphi XE, and the PerlRegEx unit in Delphi 2010 and earlier. If you’re writing new code using regular expressions in Delphi 2010 or earlier, I strongly recomment you use the new version of my PerlRegEx unit. If you later migrate your code to Delphi XE, all you have to do is replace PerlRegEx with RegularExrpessionsCore in the uses clause of your units. If you have code written using an older version of TPerlRegEx that you want to migrate to the latest TPerlRegEx, you’ll need to take a few changes into account. The original TPerlRegEx was developed when Borland’s goal was to have a component for everything on the component palette. So the old TPerlRegEx derives from TComponent, allowing you to put it on the component palette and drop it on a form. The new TPerlRegEx derives from TObject. It can only be instantiated at runtime. If you want to migrate from an older version of TPerlRegEx to the latest TPerlRegEx, start with removing any TPerlRegEx components you may have placed on forms or data modules and instantiate the objects at runtime instead. When instantiating at runtime, you no longer need to pass an owner component to the Create() constructor. Simply remove the parameter. Some of the property and method names in the original TPerlRegEx were a bit unwieldy. These have been renamed in the latest TPerlRegEx. Essentially, in all identifiers SubExpression was replaced with Group and MatchedExpression was replaced with Matched. Here is a complete list of the changed identifiers: Old Identifier New Identifier StoreSubExpression StoreGroups NamedSubExpression NamedGroup MatchedExpression MatchedText MatchedExpressionLength MatchedLength MatchedExpressionOffset MatchedOffset SubExpressionCount GroupCount SubExpressions Groups SubExpressionLengths GroupLengths SubExpressionOffsets GroupOffsets Download TPerlRegEx. Source is included under the MPL 1.1 license.

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  • C#/.NET Little Wonders: The Joy of Anonymous Types

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. In the .NET 3 Framework, Microsoft introduced the concept of anonymous types, which provide a way to create a quick, compiler-generated types at the point of instantiation.  These may seem trivial, but are very handy for concisely creating lightweight, strongly-typed objects containing only read-only properties that can be used within a given scope. Creating an Anonymous Type In short, an anonymous type is a reference type that derives directly from object and is defined by its set of properties base on their names, number, types, and order given at initialization.  In addition to just holding these properties, it is also given appropriate overridden implementations for Equals() and GetHashCode() that take into account all of the properties to correctly perform property comparisons and hashing.  Also overridden is an implementation of ToString() which makes it easy to display the contents of an anonymous type instance in a fairly concise manner. To construct an anonymous type instance, you use basically the same initialization syntax as with a regular type.  So, for example, if we wanted to create an anonymous type to represent a particular point, we could do this: 1: var point = new { X = 13, Y = 7 }; Note the similarity between anonymous type initialization and regular initialization.  The main difference is that the compiler generates the type name and the properties (as readonly) based on the names and order provided, and inferring their types from the expressions they are assigned to. It is key to remember that all of those factors (number, names, types, order of properties) determine the anonymous type.  This is important, because while these two instances share the same anonymous type: 1: // same names, types, and order 2: var point1 = new { X = 13, Y = 7 }; 3: var point2 = new { X = 5, Y = 0 }; These similar ones do not: 1: var point3 = new { Y = 3, X = 5 }; // different order 2: var point4 = new { X = 3, Y = 5.0 }; // different type for Y 3: var point5 = new {MyX = 3, MyY = 5 }; // different names 4: var point6 = new { X = 1, Y = 2, Z = 3 }; // different count Limitations on Property Initialization Expressions The expression for a property in an anonymous type initialization cannot be null (though it can evaluate to null) or an anonymous function.  For example, the following are illegal: 1: // Null can't be used directly. Null reference of what type? 2: var cantUseNull = new { Value = null }; 3:  4: // Anonymous methods cannot be used. 5: var cantUseAnonymousFxn = new { Value = () => Console.WriteLine(“Can’t.”) }; Note that the restriction on null is just that you can’t use it directly as the expression, because otherwise how would it be able to determine the type?  You can, however, use it indirectly assigning a null expression such as a typed variable with the value null, or by casting null to a specific type: 1: string str = null; 2: var fineIndirectly = new { Value = str }; 3: var fineCast = new { Value = (string)null }; All of the examples above name the properties explicitly, but you can also implicitly name properties if they are being set from a property, field, or variable.  In these cases, when a field, property, or variable is used alone, and you don’t specify a property name assigned to it, the new property will have the same name.  For example: 1: int variable = 42; 2:  3: // creates two properties named varriable and Now 4: var implicitProperties = new { variable, DateTime.Now }; Is the same type as: 1: var explicitProperties = new { variable = variable, Now = DateTime.Now }; But this only works if you are using an existing field, variable, or property directly as the expression.  If you use a more complex expression then the name cannot be inferred: 1: // can't infer the name variable from variable * 2, must name explicitly 2: var wontWork = new { variable * 2, DateTime.Now }; In the example above, since we typed variable * 2, it is no longer just a variable and thus we would have to assign the property a name explicitly. ToString() on Anonymous Types One of the more trivial overrides that an anonymous type provides you is a ToString() method that prints the value of the anonymous type instance in much the same format as it was initialized (except actual values instead of expressions as appropriate of course). For example, if you had: 1: var point = new { X = 13, Y = 42 }; And then print it out: 1: Console.WriteLine(point.ToString()); You will get: 1: { X = 13, Y = 42 } While this isn’t necessarily the most stunning feature of anonymous types, it can be handy for debugging or logging values in a fairly easy to read format. Comparing Anonymous Type Instances Because anonymous types automatically create appropriate overrides of Equals() and GetHashCode() based on the underlying properties, we can reliably compare two instances or get hash codes.  For example, if we had the following 3 points: 1: var point1 = new { X = 1, Y = 2 }; 2: var point2 = new { X = 1, Y = 2 }; 3: var point3 = new { Y = 2, X = 1 }; If we compare point1 and point2 we’ll see that Equals() returns true because they overridden version of Equals() sees that the types are the same (same number, names, types, and order of properties) and that the values are the same.   In addition, because all equal objects should have the same hash code, we’ll see that the hash codes evaluate to the same as well: 1: // true, same type, same values 2: Console.WriteLine(point1.Equals(point2)); 3:  4: // true, equal anonymous type instances always have same hash code 5: Console.WriteLine(point1.GetHashCode() == point2.GetHashCode()); However, if we compare point2 and point3 we get false.  Even though the names, types, and values of the properties are the same, the order is not, thus they are two different types and cannot be compared (and thus return false).  And, since they are not equal objects (even though they have the same value) there is a good chance their hash codes are different as well (though not guaranteed): 1: // false, different types 2: Console.WriteLine(point2.Equals(point3)); 3:  4: // quite possibly false (was false on my machine) 5: Console.WriteLine(point2.GetHashCode() == point3.GetHashCode()); Using Anonymous Types Now that we’ve created instances of anonymous types, let’s actually use them.  The property names (whether implicit or explicit) are used to access the individual properties of the anonymous type.  The main thing, once again, to keep in mind is that the properties are readonly, so you cannot assign the properties a new value (note: this does not mean that instances referred to by a property are immutable – for more information check out C#/.NET Fundamentals: Returning Data Immutably in a Mutable World). Thus, if we have the following anonymous type instance: 1: var point = new { X = 13, Y = 42 }; We can get the properties as you’d expect: 1: Console.WriteLine(“The point is: ({0},{1})”, point.X, point.Y); But we cannot alter the property values: 1: // compiler error, properties are readonly 2: point.X = 99; Further, since the anonymous type name is only known by the compiler, there is no easy way to pass anonymous type instances outside of a given scope.  The only real choices are to pass them as object or dynamic.  But really that is not the intention of using anonymous types.  If you find yourself needing to pass an anonymous type outside of a given scope, you should really consider making a POCO (Plain Old CLR Type – i.e. a class that contains just properties to hold data with little/no business logic) instead. Given that, why use them at all?  Couldn’t you always just create a POCO to represent every anonymous type you needed?  Sure you could, but then you might litter your solution with many small POCO classes that have very localized uses. It turns out this is the key to when to use anonymous types to your advantage: when you just need a lightweight type in a local context to store intermediate results, consider an anonymous type – but when that result is more long-lived and used outside of the current scope, consider a POCO instead. So what do we mean by intermediate results in a local context?  Well, a classic example would be filtering down results from a LINQ expression.  For example, let’s say we had a List<Transaction>, where Transaction is defined something like: 1: public class Transaction 2: { 3: public string UserId { get; set; } 4: public DateTime At { get; set; } 5: public decimal Amount { get; set; } 6: // … 7: } And let’s say we had this data in our List<Transaction>: 1: var transactions = new List<Transaction> 2: { 3: new Transaction { UserId = "Jim", At = DateTime.Now, Amount = 2200.00m }, 4: new Transaction { UserId = "Jim", At = DateTime.Now, Amount = -1100.00m }, 5: new Transaction { UserId = "Jim", At = DateTime.Now.AddDays(-1), Amount = 900.00m }, 6: new Transaction { UserId = "John", At = DateTime.Now.AddDays(-2), Amount = 300.00m }, 7: new Transaction { UserId = "John", At = DateTime.Now, Amount = -10.00m }, 8: new Transaction { UserId = "Jane", At = DateTime.Now, Amount = 200.00m }, 9: new Transaction { UserId = "Jane", At = DateTime.Now, Amount = -50.00m }, 10: new Transaction { UserId = "Jaime", At = DateTime.Now.AddDays(-3), Amount = -100.00m }, 11: new Transaction { UserId = "Jaime", At = DateTime.Now.AddDays(-3), Amount = 300.00m }, 12: }; So let’s say we wanted to get the transactions for each day for each user.  That is, for each day we’d want to see the transactions each user performed.  We could do this very simply with a nice LINQ expression, without the need of creating any POCOs: 1: // group the transactions based on an anonymous type with properties UserId and Date: 2: byUserAndDay = transactions 3: .GroupBy(tx => new { tx.UserId, tx.At.Date }) 4: .OrderBy(grp => grp.Key.Date) 5: .ThenBy(grp => grp.Key.UserId); Now, those of you who have attempted to use custom classes as a grouping type before (such as GroupBy(), Distinct(), etc.) may have discovered the hard way that LINQ gets a lot of its speed by utilizing not on Equals(), but also GetHashCode() on the type you are grouping by.  Thus, when you use custom types for these purposes, you generally end up having to write custom Equals() and GetHashCode() implementations or you won’t get the results you were expecting (the default implementations of Equals() and GetHashCode() are reference equality and reference identity based respectively). As we said before, it turns out that anonymous types already do these critical overrides for you.  This makes them even more convenient to use!  Instead of creating a small POCO to handle this grouping, and then having to implement a custom Equals() and GetHashCode() every time, we can just take advantage of the fact that anonymous types automatically override these methods with appropriate implementations that take into account the values of all of the properties. Now, we can look at our results: 1: foreach (var group in byUserAndDay) 2: { 3: // the group’s Key is an instance of our anonymous type 4: Console.WriteLine("{0} on {1:MM/dd/yyyy} did:", group.Key.UserId, group.Key.Date); 5:  6: // each grouping contains a sequence of the items. 7: foreach (var tx in group) 8: { 9: Console.WriteLine("\t{0}", tx.Amount); 10: } 11: } And see: 1: Jaime on 06/18/2012 did: 2: -100.00 3: 300.00 4:  5: John on 06/19/2012 did: 6: 300.00 7:  8: Jim on 06/20/2012 did: 9: 900.00 10:  11: Jane on 06/21/2012 did: 12: 200.00 13: -50.00 14:  15: Jim on 06/21/2012 did: 16: 2200.00 17: -1100.00 18:  19: John on 06/21/2012 did: 20: -10.00 Again, sure we could have just built a POCO to do this, given it an appropriate Equals() and GetHashCode() method, but that would have bloated our code with so many extra lines and been more difficult to maintain if the properties change.  Summary Anonymous types are one of those Little Wonders of the .NET language that are perfect at exactly that time when you need a temporary type to hold a set of properties together for an intermediate result.  While they are not very useful beyond the scope in which they are defined, they are excellent in LINQ expressions as a way to create and us intermediary values for further expressions and analysis. Anonymous types are defined by the compiler based on the number, type, names, and order of properties created, and they automatically implement appropriate Equals() and GetHashCode() overrides (as well as ToString()) which makes them ideal for LINQ expressions where you need to create a set of properties to group, evaluate, etc. Technorati Tags: C#,CSharp,.NET,Little Wonders,Anonymous Types,LINQ

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