magic methods - Page 136

A Look At A New Duplicate Content Technique

SEO or search engine optimization has always been considered as one of the most effective methods used in Internet marketing. This technique is much similar to SEM or search engine marketing, but off... [Author: Margarette Mcbride - Web Design and Development - May 06, 2010]

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How to implement turn-based game engine?

- by Dvole

Let's imagine game like Heroes of Might and Magic, or Master of Orion, or your turn-based game of choice. What is the game logic behind making next turn? Are there any materials or books to read about the topic? To be specific, let's imagine game loop: void eventsHandler(); //something that responds to input void gameLogic(); //something that decides whats going to be output on the screen void render(); //this function outputs stuff on screen All those are getting called say 60 times a second. But how turn-based enters here? I might imagine that in gameLogic() there is a function like endTurn() that happens when a player clicks that button, but how do I handle it all? Need insights.

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Top 5 White Hat Techniques in SEO

SEO techniques that help your site to get better page rank in search engines can be both White Hat and Black Hat. White hat techniques are accepted as ethical and useful long term, while black hat methods forcibly manipulate page rankings which are either discarded or not preferred because they flout the ethical norms. You should know the difference between these two and select a firm that utilizes only white hat techniques.

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How do you get better at selling your idea/software/pitch?

- by Sergio Tapia

How do I gain the skills to properly pitch my ideas/bids to potential clients? What are the tried and true methods of improving this very necessary skill a freelancer is supposed to have in order to survive? I have a bit of trouble trying to sell my ideas to clients and convince them that this project can be done and done well within the time they ask, but so far I feel I'm lacking in that department and I want to WOW the pants off clients from here on out. Any suggestions?

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T4MVC Add-In to auto run template

T4MVC is a fantastic solution to avoid 'Magic Strings' in ASP.NET MVC. Thanks to David Ebbo for this contribution which has made its way to MVCContrib. Must keep T4 template open and save it once.This has been the only negative thing about the template. I thought about writing an Add-In for VS to do this and even taked to David about doing it. Well, his latest post has inspired me to...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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Workshops, online content show how Oracle infuses simplicity, mobility, extensibility into user experience

- by mvaughan

By Kathy Miedema & Misha Vaughan, Oracle Applications User Experience Oracle has made a huge investment into the user experience of its many different software product families, and recent releases showcase big changes and features that aim to promote end user engagement and efficiency by streamlining navigation and simplifying the user interface. But making Oracle’s enterprise software great-looking and usable doesn’t stop when Oracle products go out the door. The Applications User Experience (UX) team recognizes that our customers may need to customize software to fit their work processes. And that’s why we provide tools such as user experience design patterns to help you maintain the Oracle user experience as you tailor your application to fit your business needs. Often, however, customers may need some context around user experience. How has the Oracle user experience been designed and constructed? Why is a good user experience important for users? How does understanding what goes into the user experience benefit the people who purchase the software for users? There’s a short answer to these questions, and you can read about it on Usable Apps. But truly understanding Oracle’s investment and seeing how it applies across product families occasionally requires a deeper dive into the Oracle user experience, especially if you’re an influencer or decision-maker about Oracle products. To help frame these decisions, the Communications & Outreach team has developed several targeted workshops that explore what Oracle means when it talks about user experience, and provides a roadmap into where the Oracle user experience is going. These workshops require non-disclosure agreements, and have been delivered to Oracle sales folks, Oracle partners, Oracle ACE Directors and ACEs, and a few customers. Some of these audience members have been developers or have a technical background; just as many did not. Here’s a breakdown of the kind of training you can get around the Oracle user experience from the OAUX Communications & Outreach team.For Partners: George Papazzian, Principal, Naviscent with Joyce Ohgi, Oracle Oracle Fusion Applications HCM Pre-Sales Seminar: In concert with Worldwide Alliances and Channels under Applications Partner Enablement Director Jonathan Vinoskey’s guidance, the Applications User Experience team delivers a two-day workshop. Day one focuses on Oracle Fusion Applications HCM and pre-sales strategy, and Day two focuses on positioning and leveraging Oracle’s investment in the Oracle Fusion Applications user experience. The next workshops will occur on the following dates: December 4-5, 2013 @ Manchester, UK January 29-30, 2014 @ Reston, Virginia February 2014 @ Guadalajara, Mexico (email: Shannon Whiteman) March 11-12, 2014 @ Dubai, United Arab Emirates April 1-2, 2014 @ Chicago, Illinois Partner Advisory Board: A two-day board meeting in the U.S. and U.K. to discuss four main user experience areas for Oracle Fusion Applications: simplicity, visualization & analytics, mobility, & futures. This event is limited to Oracle Diamond Partners, UX bloggers, and key UX influencers and requires legal documentation. We will be talking about the Oracle applications UX strategy and roadmap. Partner Implementation Training on User Interface: How to Build Great-Looking, Usable Apps: In this two-day, hands-on workshop built around Oracle’s Application Development Framework, learn how to build desktop and mobile user interfaces and mobile user interfaces based on Oracle’s experience with Fusion Applications. This workshop is for partners with a technology background who are looking for ways to tailor Fusion Applications using ADF, or have built their own custom solutions using ADF. It includes an introduction to UX design patterns and provides tools to build usability-tested UX designs. Nov 5-6, 2013 @ Redwood Shores, CA, USA January 28-29th, 2014 @ Reston, Virginia, USA February 25-26, 2014 @ Guadalajara, Mexico March 9-10, 2014 @ Dubai, United Arab Emirates To register, contact [email protected] Simplified UI Customization & Extensibility: Pilot workshop: We will be reviewing the proposed content for communicating the user experience tool kit available with the next release of Oracle Fusion Applications. Our core focus will be on what toolkit components our system implementors and independent software vendors will need to respond to customer demand, whether they are extending Fusion Applications, or building custom applications, that will need to leverage the simplified UI. Dec 11th, 2013 @ Reading, UK For information: contact [email protected] Private lab tour and demos: Interested in seeing what’s going on in the Apps UX Labs? If you are headed to the San Francisco Bay Area, let us know. We can arrange a spin through our usability labs at headquarters. OAUX Expo: This open-house forum gives partners a look at what the UX team is working on, and showcases the next-generation user experiences in a demo environment where attendees can see and touch the applications. UX Direct: Use the same methods that Oracle uses to develop its own user experiences. We help you define your users and their needs, and then provide direction on how to tailor the best user experience you can for them. For CustomersAngela Johnston, Gozel Aamoth, Teena Singh, and Yen Chan, Oracle Lab tours: See demos of soon-to-be-released products, and take a spin on usability research equipment such as our eye-tracker. Watch this video to get an idea of what you’ll see. Get our newsletter: Learn about newly released products and see where you can meet us at user group conferences. Participate in a feedback session: Join a focus group or customer feedback session to get an early look at user experience designs for the next generation of software, and provide your thoughts on how well it will work. Join the OUAB: The Oracle Usability Advisory Board meets several times a year to discuss trends in the workforce and provide direction on user experience designs. UX Direct: Use the same methods that Oracle uses to develop its own user experiences. We help you define your users and their needs, and then provide direction on how to tailor the best user experience you can for them. For Developers (customers, partners, and consultants): Plinio Arbizu, SP Solutions, Richard Bingham, Oracle, Balaji Kamepalli, EiSTechnoogies, Praveen Pillalamarri, EiSTechnologies How to Build Great-Looking, Usable Apps: This workshop is for attendees with a strong technology background who are looking for ways to tailor customer software using ADF. It includes an introduction to UX design patterns and provides tools to build usability-tested UX designs. See above for dates and times. UX design patterns web site: Cut the length of your project down by months. Use these patterns to build out the task flow you need to develop for your users. The patterns have already been usability-tested and represent the best practices that the Oracle UX research team has found in its studies. UX Direct: Use the same methods that Oracle uses to develop its own user experiences. We help you define your users and their needs, and then provide direction on how to tailor the best user experience you can for them. For Oracle Sales Mike Klein, Jeremy Ashley, Brent White, Oracle Contact your local sales person for more information about the Oracle user experience and the training available from the Applications User Experience Communications & Outreach team. See customer-friendly user experience collateral ranging from the new simplified UI in Oracle Fusion Applications Release 7, to E-Business Suite user experience highlights, to Siebel, PeopleSoft, and JD Edwards user experience highlights. Receive access to the same pre-sales and implementation training we provide to partners. For Oracle Sales only: Oracle-only training on the Oracle Fusion Applications UX Innovation Sales Kit.

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wakeonlan from remote host

- by takeshin

I have setup wake on lan service on my server. Everything works fine on local area network: root@server$: poweroff user@local$ wakeonlan AA:BB:CC:DD:EE:FF and the server wakes up. AA:BB:CC:DD:EE:FF is a MAC address of my server, which has IP 192.168.1.2 and hostname: example.com. It is connected to the router, which has IP 192.168.1.1 (public: xxx.xxx.xxx.xxx) When the server is up, I can ping: ping example.com or login via ssh: ssh [email protected] So far, so good. Now I'm able to wake the server up from local area, but how to wake the server from the remote location? I tried: user@local$ wakeonlan -i xxx.xxx.xxx.xxx AA:BB:CC:DD:EE:FF, but it does not work (nothing happens;). Do I have to configure my router somehow to forward magic packets? How?

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Good Guy Vs. Bad Guy In SEO

Search Engine Optimization, or simply called SEO, involves the use of many techniques and methods. However, like many other Internet marketing techniques, SEO is also known for its malicious or unort... [Author: Margarette Mcbride - Web Design and Development - May 02, 2010]

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SQL Server data platform upgrade - Why upgrade and how best you can reduce pre & post upgrade problems?

- by ssqa.net

SQL Server upgrade, let it be database(s) or instance(s) or both the process and procedures must follow best practices in order to reduce any problems that may occur even after the platform is upgraded. The success of any project relies upon the simpler methods of implementation and a process to reduce the complexity in testing to ensure a successful outcome. Also the topic has been a popular topic that .... read more from here ......(read more)

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A Comparative Performance Analysis of Longene VS Wine

Longene.org: Test methods: 1. Get a computer with Linux installed. 2. Install Wine and then test it with our test programs.

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What do you do before you start programming?

- by SterAllures

Heya, I'm not sure this question belongs here, it's not so much I problem I'm having with programming but rather a problem of what to do before I start programming. I want a visual representation of what variables I need and what classes have what methods.I know there is UML but I'm not sure if that is the best way, so what do you guys use before you start programming, which method? I don't want to start a flamewar about what is better just what are several approaches?

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Delegates in c#

- by Jalpesh P. Vadgama

I have used delegates in my programming since C# 2.0. But I have seen there are lots of confusion going on with delegates so I have decided to blog about it. In this blog I will explain about delegate basics and use of delegates in C#. What is delegate? We can say a delegate is a type safe function pointer which holds methods reference in object. As per MSDN it's a type that references to a method. So you can assign more than one methods to delegates with same parameter and same return type. Following is syntax for the delegate public delegate int Calculate(int a, int b); Here you can see the we have defined the delegate with two int parameter and integer parameter as return parameter. Now any method that matches this parameter can be assigned to above delegates. To understand the functionality of delegates let’s take a following simple example. using System; namespace Delegates { class Program { public delegate int CalculateNumber(int a, int b); static void Main(string[] args) { int a = 5; int b = 5; CalculateNumber addNumber = new CalculateNumber(AddNumber); Console.WriteLine(addNumber(5, 6)); Console.ReadLine(); } public static int AddNumber(int a, int b) { return a + b; } } } Here in the above code you can see that I have created a object of CalculateNumber delegate and I have assigned the AddNumber static method to it. Where you can see in ‘AddNumber’ static method will just return a sum of two numbers. After that I am calling method with the help of the delegates and printing out put to the console application. Now let’s run the application and following is the output as expected. That’s it. You can see the out put of delegates after adding a number. This delegates can be used in variety of scenarios. Like in web application we can use it to update one controls properties from another control’s action. Same you can also call a delegates whens some UI interaction done like button clicked. Hope you liked it. Stay tuned for more. In next post I am going to explain about multicast delegates. Till then happy programming.

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Test interface implementation

- by Michael

I have a interface in our code base that I would like to be able to mock out for unit testing. I am writing a test implementation to allow the individual tests to be able to override the specific methods they are concerned with rather than implementing every method. I've run into a quandary over how the test implementation should behave if the test fails to override a method used by the method under test. Should I return a "non-value" (0, null) in the test implementation or throw a UnsupportedOperationException to explicitly fail the test?

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Blazing Keywords - The Google Blazing Keywords Review

Many people who are currently attempting different methods of online marketing in order to promote and build their business have heard that keyword research is extremely vital to the success of your online marketing. Unfortunately most online marketing companies do not properly teach their members how to effectively do their keyword research in order to get good results and because of that many people are left to look for services that promise to do this for them.

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Referential Integrity: Best Practices for IBM DB2

Of the various constraints possible on relational tables, referential constraints are perhaps the most common ... and most misused. Learn about the advantages and disadvantages of different methods to implement and enforce RI, and issues that must be addressed when implementing DBMS-enforced Referential Integrity.

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Changing CSS with jQuery syntax in Silverlight using jLight

- by Timmy Kokke

Lately I’ve ran into situations where I had to change elements or had to request a value in the DOM from Silverlight. jLight, which was introduced in an earlier article, can help with that. jQuery offers great ways to change CSS during runtime. Silverlight can access the DOM, but it isn’t as easy as jQuery. All examples shown in this article can be looked at in this online demo. The code can be downloaded here. Part 1: The easy stuff Selecting and changing properties is pretty straight forward. Setting the text color in all elements can be done using the following code: jQuery.Select("b").Css("color", "red"); The Css() method is an extension method on jQueryObject which is return by the jQuery.Select() method. The Css() method takes to parameters. The first is the Css style property. All properties used in Css can be entered in this string. The second parameter is the value you want to give the property. In this case the property is “color” and it is changed to “red”. To specify which element you want to select you can add a :selector parameter to the Select() method as shown in the next example. jQuery.Select("b:first").Css("font-family", "sans-serif"); The “:first” pseudo-class selector selects only the first element. This example changes the “font-family” property of the first element to “sans-serif”. To make use of intellisense in Visual Studio I’ve added a extension methods to help with the pseudo-classes. In the example below the “font-weight” of every “Even” <LI></LI> is set to “bold”. jQuery.Select("li".Even()).Css("font-weight", "bold"); Because the Css() extension method returns a jQueryObject it is possible to chain calls to Css(). The following example show setting the “color”, “background-color” and the “font-size” of all headers in one go. jQuery.Select(":header").Css("color", "#12FF70") .Css("background-color", "yellow") .Css("font-size", "25px"); Part 2: More complex stuff In only a few cases you need to change only one style property. More often you want to change an entire set op style properties all in one go. You could chain a lot of Css() methods together. A better way is to add a class to a stylesheet and define all properties in there. With the AddClass() method you can set a style class to a set of elements. This example shows how to add the “demostyle” class to all in the document. jQuery.Select("b").AddClass("demostyle"); Removing the class works in the same way: jQuery.Select("b").RemoveClass("demostyle"); jLight is build for interacting with to the DOM from Silverlight using jQuery. A jQueryObjectCss object can be used to define different sets of style properties in Silverlight. The over 60 most common Css style properties are defined in the jQueryObjectCss class. A string indexer can be used to access all style properties ( CssObject1[“background-color”] equals CssObject1.BackgroundColor). In the code below, two jQueryObjectCss objects are defined and instantiated. private jQueryObjectCss CssObject1; private jQueryObjectCss CssObject2; public Demo2() { CssObject1 = new jQueryObjectCss { BackgroundColor = "Lime", Color="Black", FontSize = "12pt", FontFamily = "sans-serif", FontWeight = "bold", MarginLeft = 150, LineHeight = "28px", Border = "Solid 1px #880000" }; CssObject2 = new jQueryObjectCss { FontStyle = "Italic", FontSize = "48", Color = "#225522" }; InitializeComponent(); } Now instead of chaining to set all different properties you can just pass one of the jQueryObjectCss objects to the Css() method. In this case all <LI></LI> elements are set to match this object. jQuery.Select("li").Css(CssObject1); When using the jQueryObjectCss objects chaining is still possible. In the following example all headers are given a blue backgroundcolor and the last is set to match CssObject2. jQuery.Select(":header").Css(new jQueryObjectCss{BackgroundColor = "Blue"}) .Eq(-1).Css(CssObject2); Part 3: The fun stuff Having Silverlight call JavaScript and than having JavaScript to call Silverlight requires a lot of plumbing code. Everything has to be registered and strings are passed back and forth to execute the JavaScript. jLight makes this kind of stuff so easy, it becomes fun to use. In a lot of situations jQuery can call a function to decide what to do, setting a style class based on complex expressions for example. jLight can do the same, but the callback methods are defined in Silverlight. This example calls the function() method for each <LI></LI> element. The callback method has to take a jQueryObject, an integer and a string as parameters. In this case jLight differs a bit from the actual jQuery implementation. jQuery uses only the index and the className parameters. A jQueryObject is added to make it simpler to access the attributes and properties of the element. If the text of the listitem starts with a ‘D’ or an ‘M’ the class is set. Otherwise null is returned and nothing happens. private void button1_Click(object sender, RoutedEventArgs e) { jQuery.Select("li").AddClass(function); } private string function(jQueryObject obj, int index, string className) { if (obj.Text[0] == 'D' || obj.Text[0] == 'M') return "demostyle"; return null; } The last thing I would like to demonstrate uses even more Silverlight and less jLight, but demonstrates the power of the combination. Animating a style property using a Storyboard with easing functions. First a dependency property is defined. In this case it is a double named Intensity. By handling the changed event the color is set using jQuery. public double Intensity { get { return (double)GetValue(IntensityProperty); } set { SetValue(IntensityProperty, value); } } public static readonly DependencyProperty IntensityProperty = DependencyProperty.Register("Intensity", typeof(double), typeof(Demo3), new PropertyMetadata(0.0, IntensityChanged)); private static void IntensityChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { var i = (byte)(double)e.NewValue; jQuery.Select("span").Css("color", string.Format("#{0:X2}{0:X2}{0:X2}", i)); } An animation has to be created. This code defines a Storyboard with one keyframe that uses a bounce ease as an easing function. The animation is set to target the Intensity dependency property defined earlier. private Storyboard CreateAnimation(double value) { Storyboard storyboard = new Storyboard(); var da = new DoubleAnimationUsingKeyFrames(); var d = new EasingDoubleKeyFrame { EasingFunction = new BounceEase(), KeyTime = KeyTime.FromTimeSpan(TimeSpan.FromSeconds(1.0)), Value = value }; da.KeyFrames.Add(d); Storyboard.SetTarget(da, this); Storyboard.SetTargetProperty(da, new PropertyPath(Demo3.IntensityProperty)); storyboard.Children.Add(da); return storyboard; } Initially the Intensity is set to 128 which results in a gray color. When one of the buttons is pressed, a new animation is created an played. One to animate to black, and one to animate to white. public Demo3() { InitializeComponent(); Intensity = 128; } private void button2_Click(object sender, RoutedEventArgs e) { CreateAnimation(255).Begin(); } private void button3_Click(object sender, RoutedEventArgs e) { CreateAnimation(0).Begin(); } Conclusion As you can see jLight can make the life of a Silverlight developer a lot easier when accessing the DOM. Almost all jQuery functions that are defined in jLight use the same constructions as described above. I’ve tried to stay as close as possible to the real jQuery. Having JavaScript perform callbacks to Silverlight using jLight will be described in more detail in a future tutorial about AJAX or eventing.

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TSQL formatting - a sure fire way to start a conversation.

- by fatherjack

There are probably as many opinions on ways to format code as there are people writing code and I am not here to say that any one is better than any other. Well, that isn't true. I am here to say that one way is better than another but this isn't a matter of preference or personal taste, this is an example of where sloppy formatting can cause TSQL to weird and whacky things but following some simple methods can make your code more reliable and more robust when . Take these two pieces of code, ready...(read more)

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What is a Long Tail Keyword?

Did you know that a long tail keyword will out convert a root keyword 9 times out of 10. In this article, I will discuss the reasons why the long tail is a better keyword to chase than the more common methods of chasing the root.

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Keyword Optimization Tips That Work

As an online marketer or business owner who is advertising and promoting products and services online, one of the significant selling methods you ought to be acquainted with and be aware of is on page keyword optimization. Keyword optimization is an essential part in the SEO process.

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Brendan Gregg's "Systems Performance: Enterprise and the Cloud"

- by user12608550

Long ago, the prerequisite UNIX performance book was Adrian Cockcroft's 1994 classic, Sun Performance and Tuning: Sparc & Solaris, later updated in 1998 as Java and the Internet. As Solaris evolved to include the invaluable DTrace observability features, new essential performance references have been published, such as Solaris Performance and Tools: DTrace and MDB Techniques for Solaris 10 and OpenSolaris (2006) by McDougal, Mauro, and Gregg, and DTrace: Dynamic Tracing in Oracle Solaris, Mac OS X and FreeBSD (2011), also by Mauro and Gregg. Much has occurred in Solaris Land since those books appeared, notably Oracle's acquisition of Sun Microsystems in 2010 and the demise of the OpenSolaris community. But operating system technologies have continued to improve markedly in recent years, driven by stunning advances in multicore processor architecture, virtualization, and the massive scalability requirements of cloud computing. A new performance reference was needed, and I eagerly waited for something that thoroughly covered modern, distributed computing performance issues from the ground up. Well, there's a new classic now, authored yet again by Brendan Gregg, former Solaris kernel engineer at Sun and now Lead Performance Engineer at Joyent. Systems Performance: Enterprise and the Cloud is a modern, very comprehensive guide to general system performance principles and practices, as well as a highly detailed reference for specific UNIX and Linux observability tools used to examine and diagnose operating system behaviour. It provides thorough definitions of terms, explains performance diagnostic Best Practices and "Worst Practices" (called "anti-methods"), and covers key observability tools including DTrace, SystemTap, and all the traditional UNIX utilities like vmstat, ps, iostat, and many others. The book focuses on operating system performance principles and expands on these with respect to Linux (Ubuntu, Fedora, and CentOS are cited), and to Solaris and its derivatives [1]; it is not directed at any one OS so it is extremely useful as a broad performance reference. The author goes beyond the intricacies of performance analysis and shows how to interpret and visualize statistical information gathered from the observability tools. It's often difficult to extract understanding from voluminous rows of text output, and techniques are provided to assist with summarizing, visualizing, and interpreting the performance data. Gregg includes myriad useful references from the system performance literature, including a "Who's Who" of contributors to this great body of diagnostic tools and methods. This outstanding book should be required reading for UNIX and Linux system administrators as well as anyone charged with diagnosing OS performance issues. Moreover, the book can easily serve as a textbook for a graduate level course in operating systems [2]. [1] Solaris 11, of course, and Joyent's SmartOS (developed from OpenSolaris) [2] Gregg has taught system performance seminars for many years; I have also taught such courses...this book would be perfect for the OS component of an advanced CS curriculum.

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More Fun with C# Iterators and Generators

- by James Michael Hare

In my last post, I talked quite a bit about iterators and how they can be really powerful tools for filtering a list of items down to a subset of items. This had both pros and cons over returning a full collection, which, in summary, were: Pros: If traversal is only partial, does not have to visit rest of collection. If evaluation method is costly, only incurs that cost on elements visited. Adds little to no garbage collection pressure. Cons: Very slight performance impact if you know caller will always consume all items in collection. And as we saw in the last post, that con for the cost was very, very small and only really became evident on very tight loops consuming very large lists completely. One of the key items to note, though, is the garbage! In the traditional (return a new collection) method, if you have a 1,000,000 element collection, and wish to transform or filter it in some way, you have to allocate space for that copy of the collection. That is, say you have a collection of 1,000,000 items and you want to double every item in the collection. Well, that means you have to allocate a collection to hold those 1,000,000 items to return, which is a lot especially if you are just going to use it once and toss it. Iterators, though, don't have this problem. Each time you visit the node, it would return the doubled value of the node (in this example) and not allocate a second collection of 1,000,000 doubled items. Do you see the distinction? In both cases, we're consuming 1,000,000 items. But in one case we pass back each doubled item which is just an int (for example's sake) on the stack and in the other case, we allocate a list containing 1,000,000 items which then must be garbage collected. So iterators in C# are pretty cool, eh? Well, here's one more thing a C# iterator can do that a traditional "return a new collection" transformation can't! It can return **unbounded** collections! I know, I know, that smells a lot like an infinite loop, eh? Yes and no. Basically, you're relying on the caller to put the bounds on the list, and as long as the caller doesn't you keep going. Consider this example: public static class Fibonacci { // returns the infinite fibonacci sequence public static IEnumerable<int> Sequence() { int iteration = 0; int first = 1; int second = 1; int current = 0; while (true) { if (iteration++ < 2) { current = 1; } else { current = first + second; second = first; first = current; } yield return current; } } } Whoa, you say! Yes, that's an infinite loop! What the heck is going on there? Yes, that was intentional. Would it be better to have a fibonacci sequence that returns only a specific number of items? Perhaps, but that wouldn't give you the power to defer the execution to the caller. The beauty of this function is it is as infinite as the sequence itself! The fibonacci sequence is unbounded, and so is this method. It will continue to return fibonacci numbers for as long as you ask for them. Now that's not something you can do with a traditional method that would return a collection of ints representing each number. In that case you would eventually run out of memory as you got to higher and higher numbers. This method, though, never runs out of memory. Now, that said, you do have to know when you use it that it is an infinite collection and bound it appropriately. Fortunately, Linq provides a lot of these extension methods for you! Let's say you only want the first 10 fibonacci numbers: foreach(var fib in Fibonacci.Sequence().Take(10)) { Console.WriteLine(fib); } Or let's say you only want the fibonacci numbers that are less than 100: foreach(var fib in Fibonacci.Sequence().TakeWhile(f => f < 100)) { Console.WriteLine(fib); } So, you see, one of the nice things about iterators is their power to work with virtually any size (even infinite) collections without adding the garbage collection overhead of making new collections. You can also do fun things like this to make a more "fluent" interface for for loops: // A set of integer generator extension methods public static class IntExtensions { // Begins counting to inifity, use To() to range this. public static IEnumerable<int> Every(this int start) { // deliberately avoiding condition because keeps going // to infinity for as long as values are pulled. for (var i = start; ; ++i) { yield return i; } } // Begins counting to infinity by the given step value, use To() to public static IEnumerable<int> Every(this int start, int byEvery) { // deliberately avoiding condition because keeps going // to infinity for as long as values are pulled. for (var i = start; ; i += byEvery) { yield return i; } } // Begins counting to inifity, use To() to range this. public static IEnumerable<int> To(this int start, int end) { for (var i = start; i <= end; ++i) { yield return i; } } // Ranges the count by specifying the upper range of the count. public static IEnumerable<int> To(this IEnumerable<int> collection, int end) { return collection.TakeWhile(item => item <= end); } } Note that there are two versions of each method. One that starts with an int and one that starts with an IEnumerable<int>. This is to allow more power in chaining from either an existing collection or from an int. This lets you do things like: // count from 1 to 30 foreach(var i in 1.To(30)) { Console.WriteLine(i); } // count from 1 to 10 by 2s foreach(var i in 0.Every(2).To(10)) { Console.WriteLine(i); } // or, if you want an infinite sequence counting by 5s until something inside breaks you out... foreach(var i in 0.Every(5)) { if (someCondition) { break; } ... } Yes, those are kinda play functions and not particularly useful, but they show some of the power of generators and extension methods to form a fluid interface. So what do you think? What are some of your favorite generators and iterators?

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Oracle redonne un élan au Projet Lambda sur Java 7 et les closures : Interface evolution via "public

Bonjour, Depuis quelques temps, on n'entendait plus trop parler des Closures et de leur ajout à Java 7. En réponse à David Flanagan qui s'inquiétait récemment du silence d'Oracle et de la stagnation du Project Lambda, Brian Goetz (Oracle) a soumis il y a quelques jours un document de réflexion sur la notion de virtual extension methods permettant d'ajouter sur une interface existante de nouvelles méthodes (avec des implémentations par défaut) sans casser le contrat avec le code existant.

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How accurate is "Business logic should be in a service, not in a model"?

- by Jeroen Vannevel

Situation Earlier this evening I gave an answer to a question on StackOverflow. The question: Editing of an existing object should be done in repository layer or in service? For example if I have a User that has debt. I want to change his debt. Should I do it in UserRepository or in service for example BuyingService by getting an object, editing it and saving it ? My answer: You should leave the responsibility of mutating an object to that same object and use the repository to retrieve this object. Example situation: class User { private int debt; // debt in cents private string name; // getters public void makePayment(int cents){ debt -= cents; } } class UserRepository { public User GetUserByName(string name){ // Get appropriate user from database } } A comment I received: Business logic should really be in a service. Not in a model. What does the internet say? So, this got me searching since I've never really (consciously) used a service layer. I started reading up on the Service Layer pattern and the Unit Of Work pattern but so far I can't say I'm convinced a service layer has to be used. Take for example this article by Martin Fowler on the anti-pattern of an Anemic Domain Model: There are objects, many named after the nouns in the domain space, and these objects are connected with the rich relationships and structure that true domain models have. The catch comes when you look at the behavior, and you realize that there is hardly any behavior on these objects, making them little more than bags of getters and setters. Indeed often these models come with design rules that say that you are not to put any domain logic in the the domain objects. Instead there are a set of service objects which capture all the domain logic. These services live on top of the domain model and use the domain model for data. (...) The logic that should be in a domain object is domain logic - validations, calculations, business rules - whatever you like to call it. To me, this seemed exactly what the situation was about: I advocated the manipulation of an object's data by introducing methods inside that class that do just that. However I realize that this should be a given either way, and it probably has more to do with how these methods are invoked (using a repository). I also had the feeling that in that article (see below), a Service Layer is more considered as a façade that delegates work to the underlying model, than an actual work-intensive layer. Application Layer [his name for Service Layer]: Defines the jobs the software is supposed to do and directs the expressive domain objects to work out problems. The tasks this layer is responsible for are meaningful to the business or necessary for interaction with the application layers of other systems. This layer is kept thin. It does not contain business rules or knowledge, but only coordinates tasks and delegates work to collaborations of domain objects in the next layer down. It does not have state reflecting the business situation, but it can have state that reflects the progress of a task for the user or the program. Which is reinforced here: Service interfaces. Services expose a service interface to which all inbound messages are sent. You can think of a service interface as a façade that exposes the business logic implemented in the application (typically, logic in the business layer) to potential consumers. And here: The service layer should be devoid of any application or business logic and should focus primarily on a few concerns. It should wrap Business Layer calls, translate your Domain in a common language that your clients can understand, and handle the communication medium between server and requesting client. This is a serious contrast to other resources that talk about the Service Layer: The service layer should consist of classes with methods that are units of work with actions that belong in the same transaction. Or the second answer to a question I've already linked: At some point, your application will want some business logic. Also, you might want to validate the input to make sure that there isn't something evil or nonperforming being requested. This logic belongs in your service layer. "Solution"? Following the guidelines in this answer, I came up with the following approach that uses a Service Layer: class UserController : Controller { private UserService _userService; public UserController(UserService userService){ _userService = userService; } public ActionResult MakeHimPay(string username, int amount) { _userService.MakeHimPay(username, amount); return RedirectToAction("ShowUserOverview"); } public ActionResult ShowUserOverview() { return View(); } } class UserService { private IUserRepository _userRepository; public UserService(IUserRepository userRepository) { _userRepository = userRepository; } public void MakeHimPay(username, amount) { _userRepository.GetUserByName(username).makePayment(amount); } } class UserRepository { public User GetUserByName(string name){ // Get appropriate user from database } } class User { private int debt; // debt in cents private string name; // getters public void makePayment(int cents){ debt -= cents; } } Conclusion All together not much has changed here: code from the controller has moved to the service layer (which is a good thing, so there is an upside to this approach). However this doesn't look like it had anything to do with my original answer. I realize design patterns are guidelines, not rules set in stone to be implemented whenever possible. Yet I have not found a definitive explanation of the service layer and how it should be regarded. Is it a means to simply extract logic from the controller and put it inside a service instead? Is it supposed to form a contract between the controller and the domain? Should there be a layer between the domain and the service layer? And, last but not least: following the original comment Business logic should really be in a service. Not in a model. Is this correct? How would I introduce my business logic in a service instead of the model?

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Understanding and Benefiting from Code Contracts in .NET 4.0

One of the fundamental programming challenges is managing state. Chances are you have written dozens and dozens of methods that at the beginning check that certain conditions are met, and that another set of conditions is met when the method returns. With Code Contracts in .NET 4.0, you can make things considerably easier. Read on to learn how.

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