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  • Rails 3 NameError (cannot remove Object::Version) error

    - by Jeff D
    Can anyone point me at what might be causing this error? There is no ApplicationTrace, and it locks the server hard on my development machine. I think it has something to do with the way rails reloads your classes in development mode, and it appears to have something to do with a Version constant. I can't find a reference to this though. Can anyone point me in the direction of what would cause this? activesupport (3.0.3) lib/active_support/dependencies.rb:645:in `remove_const' activesupport (3.0.3) lib/active_support/dependencies.rb:645:in `remove_constant' activesupport (3.0.3) lib/active_support/dependencies.rb:645:in `instance_eval' activesupport (3.0.3) lib/active_support/dependencies.rb:645:in `remove_constant' activesupport (3.0.3) lib/active_support/dependencies.rb:521:in `remove_unloadable_constants!' activesupport (3.0.3) lib/active_support/dependencies.rb:521:in `each' activesupport (3.0.3) lib/active_support/dependencies.rb:521:in `remove_unloadable_constants!' activesupport (3.0.3) lib/active_support/dependencies.rb:317:in `clear' railties (3.0.3) lib/rails/application/bootstrap.rb:60:in `_callback_after_7' activesupport (3.0.3) lib/active_support/callbacks.rb:419:in `_run_call_callbacks' actionpack (3.0.3) lib/action_dispatch/middleware/callbacks.rb:44:in `call' rack (1.2.1) lib/rack/sendfile.rb:107:in `call' actionpack (3.0.3) lib/action_dispatch/middleware/remote_ip.rb:48:in `call' actionpack (3.0.3) lib/action_dispatch/middleware/show_exceptions.rb:46:in `call' railties (3.0.3) lib/rails/rack/logger.rb:13:in `call' rack (1.2.1) lib/rack/runtime.rb:17:in `call' activesupport (3.0.3) lib/active_support/cache/strategy/local_cache.rb:72:in `call' rack (1.2.1) lib/rack/lock.rb:11:in `call' rack (1.2.1) lib/rack/lock.rb:11:in `synchronize' rack (1.2.1) lib/rack/lock.rb:11:in `call' actionpack (3.0.3) lib/action_dispatch/middleware/static.rb:30:in `call' railties (3.0.3) lib/rails/application.rb:168:in `call' railties (3.0.3) lib/rails/application.rb:77:in `send' railties (3.0.3) lib/rails/application.rb:77:in `method_missing' railties (3.0.3) lib/rails/rack/log_tailer.rb:14:in `call' rack (1.2.1) lib/rack/content_length.rb:13:in `call' rack (1.2.1) lib/rack/handler/webrick.rb:52:in `service' /Volumes/files/jeffdeville/.rvm/rubies/ree-1.8.7-2010.02/lib/ruby/1.8/webrick/httpserver.rb:104:in `service' /Volumes/files/jeffdeville/.rvm/rubies/ree-1.8.7-2010.02/lib/ruby/1.8/webrick/httpserver.rb:65:in `run' /Volumes/files/jeffdeville/.rvm/rubies/ree-1.8.7-2010.02/lib/ruby/1.8/webrick/server.rb:173:in `start_thread' /Volumes/files/jeffdeville/.rvm/rubies/ree-1.8.7-2010.02/lib/ruby/1.8/webrick/server.rb:162:in `start' /Volumes/files/jeffdeville/.rvm/rubies/ree-1.8.7-2010.02/lib/ruby/1.8/webrick/server.rb:162:in `start_thread' /Volumes/files/jeffdeville/.rvm/rubies/ree-1.8.7-2010.02/lib/ruby/1.8/webrick/server.rb:95:in `start' /Volumes/files/jeffdeville/.rvm/rubies/ree-1.8.7-2010.02/lib/ruby/1.8/webrick/server.rb:92:in `each' /Volumes/files/jeffdeville/.rvm/rubies/ree-1.8.7-2010.02/lib/ruby/1.8/webrick/server.rb:92:in `start' /Volumes/files/jeffdeville/.rvm/rubies/ree-1.8.7-2010.02/lib/ruby/1.8/webrick/server.rb:23:in `start' /Volumes/files/jeffdeville/.rvm/rubies/ree-1.8.7-2010.02/lib/ruby/1.8/webrick/server.rb:82:in `start' rack (1.2.1) lib/rack/handler/webrick.rb:13:in `run' rack (1.2.1) lib/rack/server.rb:213:in `start' railties (3.0.3) lib/rails/commands/server.rb:65:in `start' railties (3.0.3) lib/rails/commands.rb:30 railties (3.0.3) lib/rails/commands.rb:27:in `tap' railties (3.0.3) lib/rails/commands.rb:27 script/rails:6:in `require' script/rails:6

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  • Cooking with Wessty: HTML 5 and Visual Studio

    - by David Wesst
    The hardest part about using a new technology, such as HTML 5, is getting to what features are available and the syntax. One way to learn how to use new technologies is to adapt your current development to help you use the technology in comfort of your own development environment. For .NET Web Developers, that environment is usually Visual Studio 2010. This technique intends on showing you how to get HTML 5 Intellisense working in your current version of Visual Studio 2008 or 2010, making it easier for you to start using HTML 5 features in your current .NET web development projects. Quick Note According to the Visual Web Developer team at Microsoft, the Visual Studio 2010 SP1 beta has support for both HTML 5 and CSS 3. If you are willing to try out the bleeding edge update from Microsoft, then you won’t need this technique. --- Ingredients Visual Studio 2008 or 2010 Your favourite HTML 5 compliant browser (e.g. Internet Explorer 9) Administrator privileges, or the ability to install Visual Studio Extensions in your development environment. Directions Download the HTML 5 Intellisense for Visual Studio 2008 and 2010 extension from the Visual Studio Extension Gallery. Install it. Open Visual Studio. Open up a web file, such as an HTML or ASPX file. he HTML Source Editing toolbar should have appeared. (Optional) If it did not appear, you can activate it through the main menu by selecting View, then Toolbars, and then select HTML Source Editing if it does not have a checkbox beside it. (NOTE: If there is a checkbox, then the toolbar is enabled) In the HTML Source Editing toolbar, open up the validation schema drop box, and select HTML 5. Et voila! You now have HTML 5 intellisense enabled to help you get started in adding HTML 5 awesomeness to your web sites and web applications. Optional – Setting HTML 5 Validation Options At this point, you may want to select how Visual Studio shows validation errors. You can do that in the Options Menu. To get to the Options Menu… In the main menu select Tools, then Options. In the Options window, select and expand Text Editor, then HTML, followed by selecting Validation. Resources HTML 5 Intellisense for Visual Studio 2008 and 2010 extenstion Visual Studio Extension Gallery Visual Studio 2010 SP1 Beta This post also appears at http://david.wes.st

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  • Verifying method with array passed by reference using Moq

    - by kaa
    Given the following interface public interface ISomething { void DoMany(string[] strs); void DoManyRef(ref string[] strs); } I would like to verify that the DoManyRef method is called, and passed any string array as the strs parameter. The following test fails: public void CanVerifyMethodsWithArrayRefParameter() { var a = new Mock<ISomething>().Object; var strs = new string[0]; a.DoManyRef(ref strs); var other = It.IsAny<string[]>(); Mock.Get(a).Verify(t => t.DoManyRef(ref other)); } While the following not requiring the array passed by reference passes: public void CanVerifyMethodsWithArrayParameter() { var a = new Mock<ISomething>().Object; a.DoMany(new[] { "a", "b" }); Mock.Get(a).Verify(t => t.DoMany(It.IsAny<string[]>())); } I am not able to change the interface to eliminate the by reference requirement.

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  • Visual Basic 2010: How to make window/form become active foreground?

    - by hervard
    I'm using Visual Basic 2010 Express. I have a form that can be minimized. There's also a tray icon. I've coded it so that if you double-click on the tray icon, the form's FormWindowState becomes set to Normal; this restores the form to where it to where it was before it became minimized, but the form does not become the active window on my desktop. How can I make the form become the active most foreground window? I've tried various functions that I can think of but no luck yet. Tried searching with various queries to try and find the right wording but no luck. I'm new to Visual Basic - only started a couple hours ago. Probably something simple but I can't seem to find the correct function or anything... Please enlighten me! Thanks.

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  • ASP.NET 2.0: Specifying an instance of an object for an ObjectDataSource

    - by Austin Salonen
    I'm using an ObjectDataSource to bind data to a GridView; it works fine except that it always creates a new object to use as a data source. I can do all the setup just fine but I cannot use an instance of an existing object to specify as the "data source" for it. Is it possible to do this? If so, how? If it's not possible, why? EDIT: Here's the gist of what's going on (object types changed): On the first page you are editting the attributes for a dog. One of the attributes is "has puppies" and if it's true, the next page you specify the names of those puppies. What's happening in my case is that those puppies are not getting linked to the original dog but to a "new" dog. (The implication that my problem is a "female dog" was coincidental. ;-) )

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  • Powershell / .Net: Get a reference to an object returned by a method

    - by Dan Menes
    I am teaching myself PowerShell by writing a simple parser. I use the .Net framework class Collections.Stack. I want to modify the object at the top of the stack in place. I know I can pop() the object off, modify it, and then push() it back on, but that strikes me as inelegant. First, I tried this: $stk = new-object Collections.Stack $stk.push( (,'My first value') ) ( $stk.peek() ) += ,'| My second value' Which threw an error: Assignment failed because [System.Collections.Stack] doesn't contain a settable property 'peek()'. At C:\Development\StackOverflow\PowerShell-Stacks\test.ps1:3 char:12 + ( $stk.peek <<<< () ) += ,'| My second value' + CategoryInfo : InvalidOperation: (peek:String) [], RuntimeException + FullyQualifiedErrorId : ParameterizedPropertyAssignmentFailed Next I tried this: $ary = $stk.peek() $ary += ,'| My second value' write-host "Array is: $ary" write-host "Stack top is: $($stk.peek())" Which prevented the error but still didn't do the right thing: Array is: My first value | My second value Stack top is: My first value Clearly, what is getting assigned to $ary is a copy of the object at the top of the stack, so when I the object in $ary, the object at the top of the stack remains unchanged. Finally, I read up on teh [ref] type, and tried this: $ary_ref = [ref]$stk.peek() $ary_ref.value += ,'| My second value' write-host "Referenced array is: $($ary_ref.value)" write-host "Stack top is still: $($stk.peek())" But still no dice: Referenced array is: My first value | My second value Stack top is still: My first value I assume the peek() method returns a reference to the actual object, not the clone. If so, then the reference appears to be being replaced by a clone by PowerShell's expression processing logic. Can somebody tell me if there is a way to do what I want to do? Or do I have to revert to pop() / modify / push()?

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  • How to connect to SqlExpress for Entity Framework using Visual Studio 2010 Express?

    - by Mike
    Hi everyone, I'm trying to use the Visual Studio 2010 Express editions to set up an ASP.NET MVC 2 Web Application using SqlExpress + Entity Framework as the data access. I have both the "C# Edition" and "Web Developer Edition" installed. If I try to add a data source using the "C# edition", I'm missing the "Microsoft SQL Server" data source type. but Visual Studio 2008 Professional has it. as noted by another StackOverflow question, the "Web Developer Edition" has this. However, the Web Developer Edition doesn't support the Entity Framework items: . I'd want to stick with only the Express Editions. Is my use case one that Microsoft forgot about? What can I do here to use SqlExpress + MVC 2 + Entity Framework? Thanks! -Mike

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  • How to reduce simple cpp application size? (compiled with RAD Studio 2010 cpp builder)

    - by peterg
    I am using rad studio 2010 cpp builder. I've created a new SDI application, added a TCppWebBrowser control and a simple button that onclick trigger the .navigate for the TCppWebBrowser, I compiled it and I got a 1.20mb file, I was expecting less than 700kb at least. How can I reduce the size of the compiled exe? I don't want to use "build with runtime packages", I know that will make it very small but I want to get all the necessary packages and dependencies inside the exe but maybe I am getting more than I use, I tried unchecking/removing a lot of design packages (in project/options/packages) I don't use but the file size didn't decreased. Also I was thinking maybe the TForm component that comes with RAD Studio is giving me more stuff than I need and that could make the file bigger, I mean I only need to drop a webbrowser control and a few buttons in the form, maybe there's a minimal form component I could use to replace TForm. Any suggestions will be appreciated.

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  • By-Name-Parameters for Constructors

    - by hotzen
    Hello, coming from my other question is there a way to get by-name-parameters for constructors working? I need a way to provide a code-block which is executed on-demand/lazy/by-name inside an object and this code-block must be able to access the class-methods as if the code-block were part of the class. Following Testcase fails: package test class ByNameCons(code: => Unit) { def exec() = { println("pre-code") code println("post-code") } def meth() = println("method") def exec2(code2: => Unit) = { println("pre-code") code2 println("post-code") } } object ByNameCons { def main(args: Array[String]): Unit = { val tst = new ByNameCons { println("foo") meth() // knows meth() as code is part of ByNameCons } tst.exec() // ByName fails (executed right as constructor) println("--------") tst.exec2 { // ByName works println("foo") //meth() // does not know meth() as code is NOT part of ByNameCons } } } Output: foo method pre-code post-code -------- pre-code foo post-code

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  • return value (not a reference) from the function, bound to a const reference in the calling function

    - by brainydexter
    "If you return a value (not a reference) from the function, then bind it to a const reference in the calling function, its lifetime would be extended to the scope of the calling function." So: const BoundingBox Player::GetBoundingBox(void) { return BoundingBox( &GetBoundingSphere() ); } Returns a value of type const BoundingBox from function GetBoundingBox() Called function: (From within function Update() the following is called:) variant I: (Bind it to a const reference) const BoundingBox& l_Bbox = l_pPlayer->GetBoundingBox(); variant II: (Bind it to a const copy) const BoundingBox l_Bbox = l_pPlayer->GetBoundingBox(); Both work fine and I don't see the l_Bbox object going out of scope. (Though, I understand in variant one, the copy constructor is not called and thus is slightly better than variant II). Also, for comparison, I made the following changes. BoundingBox Player::GetBoundingBox(void) { return BoundingBox( &GetBoundingSphere() ); } with Variants: I BoundingBox& l_Bbox = l_pPlayer->GetBoundingBox(); and II: BoundingBox l_Bbox = l_pPlayer->GetBoundingBox(); The objet l_Bbox still does not out scope. So, I don't see how "bind it to a const reference in the calling function, its lifetime would be extended to the scope of the calling function", really extends the lifetime of the object to the scope of the calling function ? Am I missing something trivial here..please explain .. Thanks a lot

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  • Why do C# automatic properties not support default values like VB 2010?

    - by Rob van Groenewoud
    Looking at the new VB 2010 features, I stumbled upon support for Auto-Implemented Properties. Since I'm working with C#, this seemed quite familiar, but I noticed that VB did add a feature I would love to have in C#: setting a arbitrary default value for the auto-implemented property: I really like the clean usage of auto-properties in C#. This would save us the effort of introducing a backing field and hooking it up to the property everytime we simply need a default value, thereby cluttering up the code unnecessarily. I was wondering why this wasn't introduced in C# as well? What could be the rationale for not doing this? Is a syntax discussion going on, or are there technical limitations to implementing this?

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  • Using a function with reference as a function with pointers?

    - by epatel
    Today I stumbled over a piece of code that looked horrifying to me. The pieces was chattered in different files, I have tried write the gist of it in a simple test case below. The code base is routinely scanned with FlexeLint on a daily basis, but this construct has been laying in the code since 2004. The thing is that a function implemented with a parameter passing using references is called as a function with a parameter passing using pointers...due to a function cast. The construct has worked since 2004 on Irix and now when porting it actually do work on Linux/gcc too. My question now. Is this a construct one can trust? I can understand if compiler constructors implement the reference passing as it was a pointer, but is it reliable? Are there hidden risks? Should I change the fref(..) to use pointers and risk braking anything in the process? What to you think? #include <iostream> using namespace std; // ---------------------------------------- // This will be passed as a reference in fref(..) struct string_struct { char str[256]; }; // ---------------------------------------- // Using pointer here! void fptr(const char *str) { cout << "fptr: " << str << endl; } // ---------------------------------------- // Using reference here! void fref(string_struct &str) { cout << "fref: " << str.str << endl; } // ---------------------------------------- // Cast to f(const char*) and call with pointer void ftest(void (*fin)()) { void (*fcall)(const char*) = (void(*)(const char*))fin; fcall("Hello!"); } // ---------------------------------------- // Let's go for a test int main() { ftest((void (*)())fptr); // test with fptr that's using pointer ftest((void (*)())fref); // test with fref that's using reference return 0; }

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  • Temporary non-const istream reference in constructor (C++)

    - by Christopher Bruns
    It seems that a constructor that takes a non-const reference to an istream cannot be constructed with a temporary value in C++. #include <iostream> #include <sstream> using namespace std; class Bar { public: explicit Bar(std::istream& is) {} }; int main() { istringstream stream1("bar1"); Bar bar1(stream1); // OK on all platforms // compile error on linux, Mac gcc; OK on Windows MSVC Bar bar2(istringstream("bar2")); return 0; } This compiles fine with MSVC, but not with gcc. Using gcc I get a compile error: g++ test.cpp -o test test.cpp: In function ‘int main()’: test.cpp:18: error: no matching function for call to ‘Bar::Bar(std::istringstream)’ test.cpp:9: note: candidates are: Bar::Bar(std::istream&) test.cpp:7: note: Bar::Bar(const Bar&) Is there something philosophically wrong with the second way (bar2) of constructing a Bar object? It looks nicer to me, and does not require that stream1 variable that is only needed for a moment.

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  • Cant run application (C#) through cmd

    - by user301639
    Hey, I cant execute application through cmd, when the application trying to read the argument which was sent to it (text file), it fails... when i'm truing to execute it through the IDE (vs2008), it works ok... that's what i did in the main method : static void Main(string[] args) { int choice = 0; if (args.Length == 0) choice = 1; else choice = 2; switch(choice) { case 1: { string[] text = Directory.GetFiles("allText"); Console.WriteLine(DateTime.Now.ToString()); foreach (string fileName in text) { string substring = fileName.Substring(8); ReadData_Logic rd_l = new ReadData_Logic(substring); rd_l.runThreadsAndDecrypt(); rd_l.printKey(substring.Substring(0, fileName.Length - 15).Insert(0, "encryptedKey\\") + "_result.txt"); } Console.WriteLine(DateTime.Now.ToString()); } break; case 2: { Console.WriteLine(DateTime.Now.ToString()); string fileName = args[0]; Console.WriteLine(fileName); **<--- for debug, here i do see the correct file name** ReadData_Logic rd_l = new ReadData_Logic(fileName); rd_l.runThreadsAndDecrypt(); rd_l.printKey(fileName + "_result.txt"); Console.WriteLine(DateTime.Now.ToString()); } break; } } what wrong with the code ? thanks

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  • What build param(s) to use so VS 2010 can gen .obj & link .objs but NOT create an .exe?

    - by Csourcecode
    Question title pretty much asks it all. I know I could set the project to be a .lib build and have it fail to build/link a .lib .... and the .objs tend to be in the appropriate config dir That seems like a shi*-a** backdoor way to get VS to gen objs Is there a flag/param I can set somewhere in the property sheet properties/options for Visual Studio so it links what it needs to & gens the respective objs for each source file? It's so freaking easy to just gen object files using gcc (and link in appropriate lib routines WITHOUT creating an executable) ... I'm sure I could also hack up a custom build rule but that seems like overkill [and since I'm not up to speed on the build rules for whatever version of make VS 2010 is using it's easier to ask someone else here for the simple solution]

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  • C# 4.0 'dynamic' doesn't set ref/out arguments

    - by Buu Nguyen
    I'm experimenting with DynamicObject. One of the things I try to do is setting the values of ref/out arguments, as shown in the code below. However, I am not able to have the values of i and j in Main() set properly (even though they are set correctly in TryInvokeMember()). Does anyone know how to call a DynamicObject object with ref/out arguments and be able to retrieve the values set inside the method? class Program { static void Main(string[] args) { dynamic proxy = new Proxy(new Target()); int i = 10; int j = 20; proxy.Wrap(ref i, ref j); Console.WriteLine(i + ":" + j); // Print "10:20" while expect "20:10" } } class Proxy : DynamicObject { private readonly Target target; public Proxy(Target target) { this.target = target; } public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result) { int i = (int) args[0]; int j = (int) args[1]; target.Swap(ref i, ref j); args[0] = i; args[1] = j; result = null; return true; } } class Target { public void Swap(ref int i, ref int j) { int tmp = i; i = j; j = tmp; } }

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  • Haskell IO Passes to Another Function

    - by peterwkc
    This question here is related to http://stackoverflow.com/questions/3066956/haskell-input-return-tuple I wonder how we can passes the input from monad IO to another function in order to do some computation. Actually what i want is something like -- First Example test = savefile investinput -- Second Example maxinvest :: a maxinvest = liftM maximuminvest maxinvestinput maxinvestinput :: IO() maxinvestinput = do str <- readFile "C:\\Invest.txt" let cont = words str let mytuple = converttuple cont let myint = getint mytuple putStrLn "" -- Convert to Tuple converttuple :: [String] -> [(String, Integer)] converttuple [] = [] converttuple (x:y:z) = (x, read y):converttuple z -- Get Integer getint :: [(String, Integer)] -> [Integer] getint [] = [] getint (x:xs) = snd (x) : getint xs -- Search Maximum Invest maximuminvest :: (Ord a) => [a] -> a maximuminvest [] = error "Empty Invest Amount List" maximuminvest [x] = x maximuminvest (x:xs) | x > maxTail = x | otherwise = maxTail where maxTail = maximuminvest xs In the second example, the maxinvestinput is read from file and convert the data to the type maximuminvest expected. Please help. Thanks.

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  • In the following implementation of static_strlen, why are the & and parentheses around str necessary

    - by Ben
    If I change the type to const char str[Len], I get the following error: error: no matching function for call to ‘static_strlen(const char [5])’ Am I correct that static_strlen expects an array of const char references? My understanding is that arrays are passed as pointers anyway, so what need is there for the elements to be references? Or is that interpretation completely off-the-mark? #include <iostream> template <size_t Len> size_t static_strlen(const char (&str)[Len]) { return Len - 1; } int main() { std::cout << static_strlen("oyez") << std::endl; return 0; }

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  • Returning object from function

    - by brainydexter
    I am really confused now on how and which method to use to return object from a function. I want some feedback on the solutions for the given requirements. Scenario A: The returned object is to be stored in a variable which need not be modified during its lifetime. Thus, const Foo SomeClass::GetFoo() { return Foo(); } invoked as: someMethod() { const Foo& l_Foo = someClassPInstance->GetFoo(); //... } Scneraio B: The returned object is to be stored in a variable which will be modified during its lifetime. Thus, void SomeClass::GetFoo(Foo& a_Foo_ref) { a_Foo_ref = Foo(); } invoked as: someMethod() { Foo l_Foo; someClassPInstance-GetFoo(l_Foo); //... } I have one question here: Lets say that Foo cannot have a default constructor. Then how would you deal with that in this situation, since we cant write this anymore: Foo l_Foo Scenario C: Foo SomeClass::GetFoo() { return Foo(); } invoked as: someMethod() { Foo l_Foo = someClassPInstance->GetFoo(); //... } I think this is not the recommended approach since it would incur constructing extra temporaries. What do you think ? Also, do you recommend a better way to handle this instead ?

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  • Sharepoint 2010, get the Distinct Values of a User Profile Property?

    - by Michael Stum
    Is there any way in SharePoint 2010 to get the Distinct values of a property accross all users? For example, I want a list of all Departments in the Profile Store. In SQL I can do SELECT DISTINCT(PropertyVal) FROM [ProfileDB].[dbo].[UserProfileValue] WHERE PropertyID = 14 but accessing the SQL Database is a big no-no of course, so I wonder if there is something in the object model? Note that accessing the User Information List on an SPSite is not good enough, as only a fraction of all users is in that list. I want to get it directly from the Profile Store.

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  • Delphi 2010 " is" statement behaves differently than Delphi 7's?!

    - by Tom1952
    Why does the code below return TRUE in Delphi 7 and FALSE in Delphi 2010? TBitBtn is a descendant of TButton. type TForm1 = class(TForm) Button1: TButton; BitBtn1: TBitBtn; procedure Button1Click(Sender: TObject); private public end; var Form1: TForm1; implementation {$R *.dfm} procedure TestControl( aControl: TControl); begin if (aControl is TButton) then showmessage('TRUE') else showmessage('FALSE'); end; procedure TForm1.Button1Click(Sender: TObject); begin TestControl(BitBtn1); end;

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  • Passing objects by reference or not in C#

    - by Piku
    Suppose I have a class like this: public class ThingManager { List<SomeClass> ItemList; public void AddToList (SomeClass Item) { ItemList.Add(Item); } public void ProcessListItems() { // go through list one item at a time, get item from list, // modify item according to class' purpose } } Assume "SomeClass" is a fairly large class containing methods and members that are quite complex (List<s and arrays, for example) and that there may be a large quantity of them, so not copying vast amounts of data around the program is important. Should the "AddToList" method have "ref" in it or not? And why? It's like trying to learn pointers in C all over again ;-) (which is probably why I am getting confused, I'm trying to relate these to pointers. In C it'd be "SomeClass *Item" and a list of "SomeClass *" variables)

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  • C++ Passing `this` into method by reference

    - by David
    I have a class constructor that expects a reference to another class object to be passed in as an argument. I understand that references are preferable to pointers when no pointer arithmetic will be performed or when a null value will not exist. This is the header declaration of the constructor: class MixerLine { private: MIXERLINE _mixerLine; public: MixerLine(const MixerDevice& const parentMixer, DWORD destinationIndex); ~MixerLine(); } This is the code that calls the constructor (MixerDevice.cpp): void MixerDevice::enumerateLines() { DWORD numLines = getDestinationCount(); for(DWORD i=0;i<numLines;i++) { MixerLine mixerLine( this, i ); // other code here removed } } Compilation of MixerDevice.cpp fails with this error: Error 3 error C2664: 'MixerLine::MixerLine(const MixerDevice &,DWORD)' : cannot convert parameter 1 from 'MixerDevice *const ' to 'const MixerDevice &' But I thought pointer values could be assigned to pointers, e.g. Foo* foo = new Foo(); Foo& bar = foo;

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