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  • Automatic type conversion in Java?

    - by davr
    Is there a way to do automatic implicit type conversion in Java? For example, say I have two types, 'FooSet' and 'BarSet' which both are representations of a Set. It is easy to convert between the types, such that I have written two utility methods: /** Given a BarSet, returns a FooSet */ public FooSet barTOfoo(BarSet input) { /* ... */ } /** Given a FooSet, returns a BarSet */ public BarSet fooTObar(FooSet input) { /* ... */ } Now say there's a method like this that I want to call: public void doSomething(FooSet data) { /* .. */ } But all I have is a BarSet myBarSet...it means extra typing, like: doSomething(barTOfoo(myBarSet)); Is there a way to tell the compiler that certain types can automatically be cast to other types? I know this is possible in C++ with overloading, but I can't find a way in Java. I want to just be able to type: doSomething(myBarSet); And the compiler knows to automatically call barTOfoo()

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  • java generics covariance

    - by soocracy42
    I am having trouble understanding the following article: http://www.ibm.com/developerworks/java/library/j-jtp01255.html Under, Generics are not covariant the author states, Because ln is a List, adding a Float to it seems perfectly legal. But if ln were aliased with li, then it would break the type-safety promise implicit in the definition of li -- that it is a list of integers, which is why generic types cannot be covariant. I can't understand the part where it says "if ln were aliased with li". What does the author means by alias?(reference?). The code snippet above the quoted line seems to illustrate WHAT is illegal in java and not WHY. It would be very helpful to me if somebody could explain with an example. Thanks in advance.

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  • SQL SERVER – Weekly Series – Memory Lane – #048

    - by Pinal Dave
    Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Order of Result Set of SELECT Statement on Clustered Indexed Table When ORDER BY is Not Used Above theory is true in most of the cases. However SQL Server does not use that logic when returning the resultset. SQL Server always returns the resultset which it can return fastest.In most of the cases the resultset which can be returned fastest is the resultset which is returned using clustered index. Effect of TRANSACTION on Local Variable – After ROLLBACK and After COMMIT One of the Jr. Developer asked me this question (What will be the Effect of TRANSACTION on Local Variable – After ROLLBACK and After COMMIT?) while I was rushing to an important meeting. I was getting late so I asked him to talk with his Application Tech Lead. When I came back from meeting both of them were looking for me. They said they are confused. I quickly wrote down following example for them. 2008 SQL SERVER – Guidelines and Coding Standards Complete List Download Coding standards and guidelines are very important for any developer on the path of a successful career. A coding standard is a set of guidelines, rules and regulations on how to write code. Coding standards should be flexible enough or should take care of the situation where they should not prevent best practices for coding. They are basically the guidelines that one should follow for better understanding. Download Guidelines and Coding Standards complete List Download Get Answer in Float When Dividing of Two Integer Many times we have requirements of some calculations amongst different fields in Tables. One of the software developers here was trying to calculate some fields having integer values and divide it which gave incorrect results in integer where accurate results including decimals was expected. Puzzle – Computed Columns Datatype Explanation SQL Server automatically does a cast to the data type having the highest precedence. So the result of INT and INT will be INT, but INT and FLOAT will be FLOAT because FLOAT has a higher precedence. If you want a different data type, you need to do an EXPLICIT cast. Renaming SP is Not Good Idea – Renaming Stored Procedure Does Not Update sys.procedures I have written many articles about renaming a tables, columns and procedures SQL SERVER – How to Rename a Column Name or Table Name, here I found something interesting about renaming the stored procedures and felt like sharing it with you all. The interesting fact is that when we rename a stored procedure using SP_Rename command, the Stored Procedure is successfully renamed. But when we try to test the procedure using sp_helptext, the procedure will be having the old name instead of new names. 2009 Insert Values of Stored Procedure in Table – Use Table Valued Function It is clear from the result set that , where I have converted stored procedure logic into the table valued function, is much better in terms of logic as it saves a large number of operations. However, this option should be used carefully. The performance of the stored procedure is “usually” better than that of functions. Interesting Observation – Index on Index View Used in Similar Query Recently, I was working on an optimization project for one of the largest organizations. While working on one of the queries, we came across a very interesting observation. We found that there was a query on the base table and when the query was run, it used the index, which did not exist in the base table. On careful examination, we found that the query was using the index that was on another view. This was very interesting as I have personally never experienced a scenario like this. In simple words, “Query on the base table can use the index created on the indexed view of the same base table.” Interesting Observation – Execution Plan and Results of Aggregate Concatenation Queries Working with SQL Server has never seemed to be monotonous – no matter how long one has worked with it. Quite often, I come across some excellent comments that I feel like acknowledging them as blog posts. Recently, I wrote an article on SQL SERVER – Execution Plan and Results of Aggregate Concatenation Queries Depend Upon Expression Location, which is well received in the community. 2010 I encourage all of you to go through complete series and write your own on the subject. If you write an article and send it to me, I will publish it on this blog with due credit to you. If you write on your own blog, I will update this blog post pointing to your blog post. SQL SERVER – ORDER BY Does Not Work – Limitation of the View 1 SQL SERVER – Adding Column is Expensive by Joining Table Outside View – Limitation of the View 2 SQL SERVER – Index Created on View not Used Often – Limitation of the View 3 SQL SERVER – SELECT * and Adding Column Issue in View – Limitation of the View 4 SQL SERVER – COUNT(*) Not Allowed but COUNT_BIG(*) Allowed – Limitation of the View 5 SQL SERVER – UNION Not Allowed but OR Allowed in Index View – Limitation of the View 6 SQL SERVER – Cross Database Queries Not Allowed in Indexed View – Limitation of the View 7 SQL SERVER – Outer Join Not Allowed in Indexed Views – Limitation of the View 8 SQL SERVER – SELF JOIN Not Allowed in Indexed View – Limitation of the View 9 SQL SERVER – Keywords View Definition Must Not Contain for Indexed View – Limitation of the View 10 SQL SERVER – View Over the View Not Possible with Index View – Limitations of the View 11 2011 Startup Parameters Easy to Configure If you are a regular reader of this blog, you must be aware that I have written about SQL Server Denali recently. Here is the quickest way to reach into the screen where we can change the startup parameters. Go to SQL Server Configuration Manager >> SQL Server Services >> Right Click on the Server >> Properties >> Startup Parameters 2012 Validating Unique Columnname Across Whole Database I sometimes come across very strange requirements and often I do not receive a proper explanation of the same. Here is the one of those examples. For example “Our business requirement is when we add new column we want it unique across current database.” Read the solution to this strange request in this blog post. Excel Losing Decimal Values When Value Pasted from SSMS ResultSet It is very common when users are coping the resultset to Excel, the floating point or decimals are missed. The solution is very much simple and it requires a small adjustment in the Excel. By default Excel is very smart and when it detects the value which is getting pasted is numeric it changes the column format to accommodate that. Basic Calculation and PEMDAS Order of Operation Read this interesting blog post for fantastic conversation about the subject. Copy Column Headers from Resultset – SQL in Sixty Seconds #027 – Video http://www.youtube.com/watch?v=x_-3tLqTRv0 Delete From Multiple Table – Update Multiple Table in Single Statement There are two questions which I get every single day multiple times. In my gmail, I have created standard canned reply for them. Let us see the questions here. I want to delete from multiple table in a single statement how will I do it? I want to update multiple table in a single statement how will I do it? Read the answer in the blog post. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • IntelliSense for Razor Hosting in non-Web Applications

    - by Rick Strahl
    When I posted my Razor Hosting article a couple of weeks ago I got a number of questions on how to get IntelliSense to work inside of Visual Studio while editing your templates. The answer to this question is mainly dependent on how Visual Studio recognizes assemblies, so a little background is required. If you open a template just on its own as a standalone file by clicking on it say in Explorer, Visual Studio will open up with the template in the editor, but you won’t get any IntelliSense on any of your related assemblies that you might be using by default. It’ll give Intellisense on base System namespace, but not on your imported assembly types. This makes sense: Visual Studio has no idea what the assembly associations for the single file are. There are two options available to you to make IntelliSense work for templates: Add the templates as included files to your non-Web project Add a BIN folder to your template’s folder and add all assemblies required there Including Templates in your Host Project By including templates into your Razor hosting project, Visual Studio will pick up the project’s assembly references and make IntelliSense available for any of the custom types in your project and on your templates. To see this work I moved the \Templates folder from the samples from the Debug\Bin folder into the project root and included the templates in the WinForm sample project. Here’s what this looks like in Visual Studio after the templates have been included:   Notice that I take my original example and type cast the Context object to the specific type that it actually represents – namely CustomContext – by using a simple code block: @{ CustomContext Model = Context as CustomContext; } After that assignment my Model local variable is in scope and IntelliSense works as expected. Note that you also will need to add any namespaces with the using command in this case: @using RazorHostingWinForm which has to be defined at the very top of a Razor document. BTW, while you can only pass in a single Context 'parameter’ to the template with the default template I’ve provided realize that you can also assign a complex object to Context. For example you could have a container object that references a variety of other objects which you can then cast to the appropriate types as needed: @{ ContextContainer container = Context as ContextContainer; CustomContext Model = container.Model; CustomDAO DAO = container.DAO; } and so forth. IntelliSense for your Custom Template Notice also that you can get IntelliSense for the top level template by specifying an inherits tag at the top of the document: @inherits RazorHosting.RazorTemplateFolderHost By specifying the above you can then get IntelliSense on your base template’s properties. For example, in my base template there are Request and Response objects. This is very useful especially if you end up creating custom templates that include your custom business objects as you can get effectively see full IntelliSense from the ‘page’ level down. For Html Help Builder for example, I’d have a Help object on the page and assuming I have the references available I can see all the way into that Help object without even having to do anything fancy. Note that the @inherits key is a GREAT and easy way to override the base template you normally specify as the default template. It allows you to create a custom template and as long as it inherits from the base template it’ll work properly. Since the last post I’ve also made some changes in the base template that allow hooking up some simple initialization logic so it gets much more easy to create custom templates and hook up custom objects with an IntializeTemplate() hook function that gets called with the Context and a Configuration object. These objects are objects you can pass in at runtime from your host application and then assign to custom properties on your template. For example the default implementation for RazorTemplateFolderHost does this: public override void InitializeTemplate(object context, object configurationData) { // Pick up configuration data and stuff into Request object RazorFolderHostTemplateConfiguration config = configurationData as RazorFolderHostTemplateConfiguration; this.Request.TemplatePath = config.TemplatePath; this.Request.TemplateRelativePath = config.TemplateRelativePath; // Just use the entire ConfigData as the model, but in theory // configData could contain many objects or values to set on // template properties this.Model = config.ConfigData as TModel; } to set up a strongly typed Model and the Request object. You can do much more complex hookups here of course and create complex base template pages that contain all the objects that you need in your code with strong typing. Adding a Bin folder to your Template’s Root Path Including templates in your host project works if you own the project and you’re the only one modifying the templates. However, if you are distributing the Razor engine as a templating/scripting solution as part of your application or development tool the original project is likely not available and so that approach is not practical. Another option you have is to add a Bin folder and add all the related assemblies into it. You can also add a Web.Config file with assembly references for any GAC’d assembly references that need to be associated with the templates. Between the web.config and bin folder Visual Studio can figure out how to provide IntelliSense. The Bin folder should contain: The RazorHosting.dll Your host project’s EXE or DLL – renamed to .dll if it’s an .exe Any external (bin folder) dependent assemblies Note that you most likely also want a reference to the host project if it contains references that are going to be used in templates. Visual Studio doesn’t recognize an EXE reference so you have to rename the EXE to DLL to make it work. Apparently the binary signature of EXE and DLL files are identical and it just works – learn something new everyday… For GAC assembly references you can add a web.config file to your template root. The Web.config file then should contain any full assembly references to GAC components: <configuration> <system.web> <compilation debug="true"> <assemblies> <add assembly="System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" /> <add assembly="System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" /> <add assembly="System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" /> </assemblies> </compilation> </system.web> </configuration> And with that you should get full IntelliSense. Note that if you add a BIN folder and you also have the templates in your Visual Studio project Visual Studio will complain about reference conflicts as it’s effectively seeing both the project references and the ones in the bin folder. So it’s probably a good idea to use one or the other but not both at the same time :-) Seeing IntelliSense in your Razor templates is a big help for users of your templates. If you’re shipping an application level scripting solution especially it’ll be real useful for your template consumers/users to be able to get some quick help on creating customized templates – after all that’s what templates are all about – easy customization. Making sure that everything is referenced in your bin folder and web.config is a good idea and it’s great to see that Visual Studio (and presumably WebMatrix/Visual Web Developer as well) will be able to pick up your custom IntelliSense in Razor templates.© Rick Strahl, West Wind Technologies, 2005-2011Posted in Razor  

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  • Fastest way to do mass update

    - by user356004
    Let’s say you have a table with about 5 million records and a nvarchar(max) column populated with large text data. You want to set this column to NULL if SomeOtherColumn = 1 in fastest possible way. The brute force UPDATE does not work very well here because it will create large implicit transaction and take forever. Doing updates in small batches of 50K records at a time works but it’s still taking 47 hrs to complete on beefy 32 core/64GB server. Is there any way to do this update faster? Are there any magic query hints/table options that scarifies something else (like concurrency) in exchange of speed? NOTE: Creating temp table or temp column is not an option because this nvarchar(max) column involves lots of data and so consumes lots of space!

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  • Nullable Enum nullable type question

    - by Michael Kniskern
    I get the following compilation error with the following source code: Compilation Error: Type of conditional expression cannot be determined because there is no implicit conversion between '' and 'MyEnum' Source Code public enum MyEnum { Value1, Value2, Value3 } public class MyClass { public MyClass() {} public MyEnum? MyClassEnum { get; set; } } public class Main() { object x = new object(); MyClass mc = new MyClass() { MyClassEnum = Convert.IsDBNull(x) : null ? (MyEnum) Enum.Parse(typeof(MyEnum), x.ToString(), true) }; } How can I resolve this error?

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  • Scala type conversion error, need help!

    - by Mansoor Ashraf
    Hello I am getting a weird error when trying to use a Java map in Scala. This is the snippet of code val value:Double = map.get(name) if (value eq null) map.put(name, time) else map.put(name, value + time) the map is defined as val map=new ConcurrentHashMap[String,Double] and this is the error I am getting error: type mismatch; found : Double required: ?{val eq: ?} Note that implicit conversions are not applicable because they are ambiguous: both method double2Double in object Predef of type (Double)java.lang.Double and method doubleWrapper in object Predef of type (Double)scala.runtime.RichDouble are possible conversion functions from Double to ?{val eq: ?} if (value eq null) map.put(name, time) I am new to Scala so I am having a hard time parsing the stacktrace. Any help would be appreciated

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  • eclipse xdebug session never completes

    - by Scott
    I am trying to get xdebug working with eclipse (3.5) / php (on xampp windows 7). I have verified xdebug is enabled in php - I have the fancy output and my phpinfo shows all the xdebug stuff. I have remote debug on, and typed in the lan ip address on my eclipse machine. When I tell eclipse to debug, it launches the browser and passes the debug URL parameters. That looks OK. However, in eclipse debug perspective it shows 'launching myproject' 57% 'waiting for xdebug session'. It sits there forever. I have turned off windows firewall on both machines. I tried turning implicit flush on. Any ideas?

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  • Database security / scaling question

    - by orokusaki
    Typically I use a database such as MySQL or PostGreSQL on the same machine as the application using it, which makes access easy and secure. I'm just now building the first site that will have a separate physical database server (later this year it will). I'm wondering 3 things: (security) What things should I look into for starters pertaining to security of accessing a separate machine's database? (scalability) Are their scalability issues that I should think about pertaining to this (technology agnostic)? (more ServerFaultish but related) If starting the DB out on the same physical server (using a separate VMWare VM) and later moving to a different physical server, are there implicit problems that I'll have to deal with? Isn't another VM still accessed via localhost? If these questions are completely ludicrous, I apologize to you DB experts.

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  • Scala 2.8 TreeMap and custom Ordering

    - by Dave
    I'm switching from scala 2.7 and ordered to scala 2.8 and using ordering. It looks quite straight forward but I was wondering could I make it a little less verbose. For example: scala> case class A(i: Int) defined class A scala> object A extends Ordering[A] { def compare(o1: A, o2: A) = o1.i - o2.i} defined module A If I then try to create a TreeMap I get an error scala> new collection.immutable.TreeMap[A, String]() <console>:10: error: could not find implicit value for parameter ordering: Ordering[A] new collection.immutable.TreeMap[A, String]() ^ However if I explicitly specify the object A as the ordering it works fine. scala> new collection.immutable.TreeMap[A, String]()(A) res34: scala.collection.immutable.TreeMap[A,String] = Map() Do I always have to explicitly specify the ordering or is there a shorter format? Thanks

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  • adobe flash buider (flex4): addChild() is not available in this class.

    - by ufk
    Hi. I want to be able to load an swf into a flex 4 application in order to use it's classes. var ldr:Loader=new Loader(); ldr.load(new URLRequest("file://path/to/fileswf")); ldr.contentLoaderInfo. addEventListener(Event.INIT, loaded); function loaded(evt:Event):void { addChild(ldr); } i receive the error: Error: addChild() is not available in this class. Instead, use addElement() or modify the skin, if you have one. at spark.components.supportClasses::SkinnableComponent/addChild()[E:\dev\gumbo_beta2\frameworks\projects\spark\src\spark\components\supportClasses\SkinnableComponent.as:966] at main/private:init/loaded()[C:\Documents and Settings\ufk\Adobe Flash Builder Beta 2\xpogames-toolkit-test\src\main.mxml:22] if i change addChild() to addElement() i receive the following compilation error: 1067: Implicit coercion of a value of type flash.display:Loader to an unrelated type mx.core:IVisualElement. main.mxml path/dir line 22 Flex Problem any ideas how to resolve the issue ?

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  • eclipse xdebug session never completes

    - by Scott Szretter
    I am trying to get xdebug working with eclipse (3.5) / php (on xampp windows 7). I have verified xdebug is enabled in php - I have the fancy output and my phpinfo shows all the xdebug stuff. I have remote debug on, and typed in the lan ip address on my eclipse machine. When I tell eclipse to debug, it launches the browser and passes the debug URL parameters. That looks OK. However, in eclipse debug perspective it shows 'launching myproject' 57% 'waiting for xdebug session'. It sits there forever. I have turned off windows firewall on both machines. I tried turning implicit flush on. Any ideas?

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  • My presentation layer does not match my model layer even though I have no animations

    - by Kevin McCullough
    On iPhone I have a CALayer that I animate via Core Animation. Then at some point I change view controllers. I then return to the view controller with the CALayer and in viewWillAppear: I set the frame and position properties on my layer to move it back to its starting point. Setting these properties changes the model layer but the presentation layer still has the old values and its presentation layer does not update until the next animation I play. In the CA Programming guide it says "You can query an instance of CALayer for its corresponding presentation layer while an animation transaction is in process." Which, to me, implies that the presentation layer should only be different from the model layer during an animation. But there are no animations currently running. I even used kCATransactionDisableActions to ensure that when I set the position property an implicit animation is not started. Does anyone know why my presentation and model layers are out of sync? Thanks.

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  • Static Class Variables in Dynamic Library and Main Program

    - by Paul
    I am working on a project that has a class 'A' that contains a static stl container class. This class is included in both my main program and a .so file. The class uses the default(implicit, not declared) constructor/destructor. The main program loads the .so file using dlopen() and in its destructor, calls dlclose(). The program crashes after main exits when glibc calls the destructor for the static class member variable. The problem appears to be that when dlclose() is called, the destructor for the static variable is called, then when main exits() glibc also calls the destructor, resulting in a double free. I have 2 questions, namely: 1) In this particular case, why are there not two copies of the static variable(yes i know that sounds somewhat ridiculous, but since both the main program and .so file have a separately compiled 'A', shouldn't they each have one?) 2) Is there any way to resolve this issue without re-writing class 'A' to not contain static member variables?

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  • Is there a way to pass a custom type from C# to Oracle using System.Data.OracleClient?

    - by Frankie Simon
    I was searching online for a solution to passing a string array to a stored procedure in Oracle. The "easy" but messy way was using a comma delimited string. I had found a sample based on which I created my own type of TABLE of VARCHAR2(200). I understood that I could use a constructor created "behind-the-scenes" by Oracle to give a list of values that would, in the PL/SQL, be treated as a TABLE I could iterate through. But when I got to the C# I saw that there is no way for me to create an OracleParameter object that would allow me to use this implicit constructor. All the samples I'm finding online for now are dealing with Oracle Data Adapter, none say anything about System.Data.OracleClient. Is there a way to achieve this?

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  • Django on Dreamhost - testing/sand box environment

    - by elequ
    I've been using webfaction for all my django needs for the last couple of years but have had a high traffic site fall in my lap that dreamhost are probably better suited to handling. To set up and experiment with a site with webfaction there are your [user].webfactional.com accounts. Which is sweet. Equivalently Dreamhost also offers [name].dreamhosters.com Yet this doesn't seem to work with my database and this doesn't seem to be playing nice with setting up django or passenger_wsgi. So I'm wondering if I'm interpreting the documentation correctly to suggest that in order to make a site that depends on passenger it needs to be running from an active domain. The documentation is really implicit, I'm baffled. Has anyone set up a testing/sand box environment for django using dreamhost, or know how to?

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  • DataTemplate defautl visibility for ContentControls

    - by bitbonk
    In my MVVM based WPF application I have a lot of different ViewModel types that dynamically loaded into ContentControls or ContentPresenters. Therefor I need to explictly set what DataTemplate is to be used in XAML: <ContentControl Content={Binding SomePropertyOfTypeViewModel} ContentTemplate={StaticResource someTemplate} /> Now my problem is that the content control is displaying the UI of someTemplate even if the ContentControl is bound to nothing (i.e ViewModel.SomePropertyOfTypeViewModel is null) Is there a quick and easy way to make all ContentControls display nothing if they are currently bound to nothing? When I use implicit DataTemplates everything works as expected. Unfortunately I can't use this mechanism here.

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  • MVC DateTime binding with incorrect date format

    - by Sam Wessel
    Asp.net-MVC now allows for implicit binding of DateTime objects. I have an action along the lines of public ActionResult DoSomething(DateTime startDate) { ... } This successfully converts a string from an ajax call into a DateTime. However, we use the date format dd/MM/yyyy; MVC is converting to MM/dd/yyyy. For example, submitting a call to the action with a string '09/02/2009' results in a DateTime of '02/09/2009 00:00:00', or September 2nd in our local settings. I don't want to roll my own model binder for the sake of a date format. But it seems needless to have to change the action to accept a string and then use DateTime.Parse if MVC is capable of doing this for me. Is there any way to alter the date format used in the default model binder for DateTime? Shouldn't the default model binder use your localisation settings anyway?

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  • Does C99 guarantee that arrays are contiguous ?

    - by kriss
    Following an hot comment thread in another question, I came to debate of what is and what is not defined in C99 standard about C arrays. Basically when I define a 2D array like int a[5][5], does the standard C99 garantee or not that it will be a contiguous block of ints, can I cast it to (int *)a and be sure I will have a valid 1D array of 25 ints. As I understand the standard the above property is implicit in the sizeof definition and in pointer arithmetic, but others seems to disagree and says casting to (int*) the above structure give an undefined behavior (even if they agree that all existing implementations actually allocate contiguous values). More specifically, if we think an implementation that would instrument arrays to check array boundaries for all dimensions and return some kind of error when accessing 1D array, or does not give correct access to elements above 1st row. Could such implementation be standard compilant ? And in this case what parts of the C99 standard are relevant.

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  • Parallelism in Python

    - by fmark
    What are the options for achieving parallelism in Python? I want to perform a bunch of CPU bound calculations over some very large rasters, and would like to parallelise them. Coming from a C background, I am familiar with three approaches to parallelism: Message passing processes, possibly distributed across a cluster, e.g. MPI. Explicit shared memory parallelism, either using pthreads or fork(), pipe(), et. al Implicit shared memory parallelism, using OpenMP. Deciding on an approach to use is an exercise in trade-offs. In Python, what approaches are available and what are their characteristics? Is there a clusterable MPI clone? What are the preferred ways of achieving shared memory parallelism? I have heard reference to problems with the GIL, as well as references to tasklets. In short, what do I need to know about the different parallelization strategies in Python before choosing between them?

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  • Access block level storage via kernel

    - by N 1.1
    How to access block level storage via the kernel (w/o using scsi libraries)? My intent is to implement a block level storage protocol over network for learning purpose, almost the same way SCSI works. Requests will be generated by initiator and sent to target (both userspace program) which makes call to kernel module and returns the data using TCP protocol to initiator. So far, I have managed to build a simple "Hello" module and run it (I am new at kernel programming), but unable to proceed with block access. After searching a lot, I found struct buffer_head * bread(int dev,int block) in linux/fs.h, but the compiler throws error. error: implicit declaration of function ‘bread’ Please help, also feel free to advice on starting with kernel programming. Thank you!

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  • What was the most surprising failure of your 'Engineer's intuition'?

    - by Bubba88
    Hi! This may seem as an open-ended question but I'll surely accept the most impressive and upvoted answer ;) Basically, I could describe my own case - I just fail 5 times a day with my intuition cause very frequently I can be just not up-to-the-speed with my requirements/manager/team/etc. and I just have to make code quickly - that's why proper formalization in many cases stands aside. I want to gather some experience of yours - what was the most epic failure when you did rely on you implicit reasoning/intuitive knowledge/immediate perception etc. of course everything you describe should be related to programming/computers. It's mostly just to measure the danger of using that 'it's obvious..' words. I've made it com. wiki to be properly transformed after gathering enough views count. Thank you!

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  • MySQL Create tables without commiting current transaction

    - by user276648
    I'd like my program to be able to install plugins, and rollback all the changes made if an error occurs. So I create a transaction that keeps all the things that were added while installing the plugin. The problem is that the plugin may want to create tables, and doing so automatically commits the current transaction in MySQL. See Statements That Cause an Implicit Commit on MySQL web site. Any idea on how I could do it? I thought of using temporary tables as they are not automatically commited, unless they are using too much memory, but it looks like temporary tables cannot be rolled back anyway (and I haven't found a way to convert them to permanent tables). I just found out about "save points" (http://dev.mysql.com/doc/refman/5.1/en/savepoint.html), but I don't really understand how/when it should be used nor if it can help me achieve what I want.

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  • Print a bitmap without printing a sprite?

    - by Carlos Barbosa
    Following up from: http://stackoverflow.com/questions/3021557/as3-printing-problem-blanks-swf-after-print-or-cancel I am trying to comeup with a function to print without creating a sprite, because that's what it seems to be causing my problem: public function printScreen():void { var pJob:PrintJob = new PrintJob(); var options:PrintJobOptions = new PrintJobOptions(); options.printAsBitmap = true; var bitmapData:BitmapData = new BitmapData(root.width, root.height); bitmapData.draw(root); var printThis:Bitmap = new Bitmap(bitmapData); try { pJob.start(); pJob.addPage(printThis, null, options); pJob.send(); } catch(e:Error) { trace("Error Printing") } } This is coming up with an: Error: Description Implicit coercion of a value of type flash.display:Bitmap to an unrelated type flash.display:Sprite. So how do you print a bitmap without creating a Sprite?

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  • C# - Convert Implict Type to ObservableCollection

    - by user70192
    Hello, I have a LINQ statement that returns an implicit type. I need to get this type to be an ObservableCollection in my Silverlight 3 application. The ObservableCollection constructor in Silverlight 3 only provides an empty constructor. Because of this, I cannot directly convert my results to an ObservableCollection. Here is my code: ObservableCollection<MyTasks> visibleTasks = e.Result; var filteredResults = from visibleTask in visibleTasks select visibleTask; filteredResults = filteredResults.Where(p => p.DueDate == DateTime.Today); visibleTasks = filteredResults.ToList(); // This throws a compile time error How can I go from an implicitly typed variable to an observable collection? Thank you

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