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• What are the requirements of a collection type when model binding?

  - by Richard Ev

  I have been reviewing model binding with collections, specifically going through this article http://weblogs.asp.net/nmarun/archive/2010/03/13/asp-net-mvc-2-model-binding-for-a-collection.aspx However, the model I would like to use in my code does not implement collections using generic lists. Instead it uses its own collection classes, which inherit from a custom generic collection base class, the declaration of which is public abstract class CollectionBase<T> : IEnumerable<T> The collections in my POSTed action method are all non-null, but contain no elements. Can anyone advise?

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• Java: ListA.addAll(ListB) fires NullPointerException?

  - by HH

  The err part is Capitalized in the code, it also comes in foreaching. Because of the abstract list, it cannot be initialized, declaration is in a static field. The lists have the same type. import java.util.*; public class Test { public static final List<String> highPrio = Arrays.asList("*","/"); public static List<String> ops; public static void main(String[] args) { //ERROR HERE, why do it throw nullPointer? ops.addAll(highPrio); for(String s : ops) { System.out.println(s); } } }

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• Why is this not a valid XML DTD? (Parameter entity and #PCDATA)

  - by user68759

  Hi, Using the DTD validator here, I am informed that the following DTD is invalid. <!ENTITY % text "(#PCDATA|L)*"> <!ELEMENT H (%text;)+> <!ELEMENT L (#PCDATA)> The error message is: "A '(' character or an element type is required within declaration of element type "H"." at line 2, column 22. Can anyone please point out why it is invalid? The error message is not exactly very friendly to me. Thanks.

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• How to align C++ class member names in one column in emacs ?

  - by KotBerbelot

  I would like to align all C++ class member names ( do not confuse with member types ) in one column. Lets look at the example of what we have at entrance: class Foo { public: void method1( ); int method2( ); const Bar * method3( ) const; protected: float m_member; }; and this is what we would like to have at the end: class Foo { public: void method1( ); int method2( ); const Bar * method3( ) const; protected: float m_member; }; So the longest member type declaration defines the column to which class member names will be aligned. How can i perform such transformation in emacs ?

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• C++ Singleton design pattern

  - by Artem Barger

  Recently I've bumped into a realization/implementation of the Singleton design pattern for C++. It has looked like this (I have adopted it from the real life example): // a lot of methods are omitted here class Singleton { public: static Singleton* getInstance( ); ~Singleton( ); private: Singleton( ); static Singleton* instance; }; From this declaration I can deduce that the instance field is initiated on the heap. That means there is a memory allocation. What is completely unclear for me is when exactly the memory is going to be deallocated? Or is there a bug and memory leak? It seems like there is a problem in the implementation. My main question is, how do I implement it in the right way?

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• How do I print the method body reflectively?

  - by kunjaan

  Right now I have private static void getMethods(Class<? extends Object> clazz) { Method[] declaredMethods = clazz.getDeclaredMethods(); for (Method aMethod : declaredMethods) { aMethod.setAccessible(true); // Print the declaration System.out.print(Modifier.toString(aMethod.getModifiers()) + " " + aMethod.getReturnType().getSimpleName() + " " + aMethod.getName()); // Get Parameter Types getParameters(aMethod); //Empty Body System.out.println("{}\n"); } } Which prints most information reflectively but creates an empty body. How do I add to the reflective nature of Java to print the method body?

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• How can I declare a pointer with filled information in C++?

  - by chacham15

  typedef struct Pair_s { char *first; char *second; } Pair; Pair pairs[] = { {"foo", "bar"}, //this is fine {"bar", "baz"} }; typedef struct PairOfPairs_s { Pair *first; Pair *second; } PairOfPairs; PairOfPairs pops[] = { {{"foo", "bar"}, {"bar", "baz"}}, //How can i create an equivalent of this NEATLY {&pairs[0], &pairs[1]} //this is not considered neat (imagine trying to read a list of 30 of these) }; How can I achieve the above style declaration semantics?

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• Calling C++/CLI Method with System::DateTime parameter requires 'ValueType' as a parameter?

  - by David Ipsen

  I'm attempting to call a method written in C++/CLI from C#. The C++/CLI code is used to update a TIMESTAMP column in an Oracle database, given a record ID and the System::DateTime object which is the .NET compatible data type for Oracle's TIMESTAMP type. The method I am calling has the following prototype: bool ChangeJobUpdateDate (int jobIdIn, System::DateTime^ updateDateIn) I've added a reference to this DLL project in a test project that I made; I'm writing the tests in C#. However, when I try to call this method from the C# unit test project, the function appears to have the following method declaration (via intellisense): bool ChangeJobUpdateDate (int jobIdIn, ValueType updateDateIn) I'm admittedly not that familiar with C++/CLI, so is there something I'm missing?

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• F# - Function with no arguments?

  - by Rubys

  When thinking in a functional mindset, given that functions are supposed to be pure, one can conclude any function with no arguments is basically just a value. However, reallity gets in the way, and with different inputs, I might not need a certain function, and if that function is computationally expensive, I'd like to not evaluate it if it's not needed. I found a workaround, using let func _ = ... and calling it with func 1 or whatever, but that feels very non-idiomatic and confusing to the reader. This boils down to one question: In F#, Is there a proper way to declare a function with zero arguments, without having it evaluated on declaration?

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• aligning extern constants (gcc)

  - by ~buratinas

  I want to make some static constants globally visible. I'm pretty familiar how to do that in C++. The problem is that these constants need to be aligned to some exotic boundary. Do I have to specify the alignment in extern declaration? I'm using GCC4.5 in *.cpp file static const constant_t constant __attribute__((aligned(64))) = {blah,blah,blah}; in *.h file //Which one is correct? extern const constant_t constant; extern const constant_t constant __attribute__((aligned(64)));

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• What's the syntax to import a class in a default package in Java?

  - by Lord Torgamus

  Possible Duplicate: How to access java-classes in the default-package? Is it possible to import a class in Java which is in the default package? If so, what is the syntax? For example, if you have package foo.bar; public class SomeClass { // ... in one file, you can write package baz.fonz; import foo.bar.SomeClass; public class AnotherClass { SomeClass sc = new SomeClass(); // ... in another file. But what if SomeClass.java does not contain a package declaration? How would you refer to SomeClass in AnotherClass?

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• How do I link (dependency) properties in my ViewModel?

  - by mos

  Simplified example: I have an object that models a user. Users have a first name and a last name. The UserViewModel has a dependency property for my Models.User object. In the declaration of the UserView's xaml, I want to bind a couple of TextBlocks to the first and last name properties. What is the correct way to do this? Should I have readonly DependencyProperties for the name fields, and when the dependency property User is set, update them? Can the name fields be regular C# properties instead? Or, should I bind like this: <TextBlock Text="{Binding User.FirstName}" />

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• Set argument pointer to point to new memory inside a function (without returning it) IN C

  - by user321605

  Hello, Hopefully my title was descriptive enough to attract the right help. I want to write a function that will return 1 thing, and modify a provided pointer in another. My current function declaration is . . . char * afterURL replaceURLS(char * body) What I want to do is copy all of body's data into a new string, and set body to point to this new data. I then want afterURL to point to a location within the new string. My issue is getting the actual pointer that is passed in to this function to point to the new data. Thanks in advance! Rob

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• template function error..

  - by sil3nt

  Hi there, I have function which takes in an parameter of a class called "Triple", and am returning the averge of 3 values of type float. template <typename ElemT> float average(Triple ElemT<float> &arg){ float pos1 = arg.getElem(1); float pos2 = arg.getElem(2); float pos3 = arg.getElem(3); return ( (pos1+pos2+po3) /3 ); } when i try compiling this i get q2b.cpp:32: error: template declaration of `float average' q2b.cpp:32: error: missing template arguments before "ElemT" not quite sure what this means.

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• Substitute all matches with values in Ruby regular expression

  - by Lewisham

  Hi all, I'm having a problem with getting a Ruby string substitution going. I'm writing a preprocessor for a limited language that I'm using, that doesn't natively support arrays, so I'm hacking in my own. I have a line: x[0] = x[1] & x[1] = x[2] I want to replace each instance with a reformatted version: x__0 = x__1 & x__1 = x__2 The line may include square brackets elsewhere. I've got a regex that will match the array use: array_usage = /(\w+)\[(\d+)\]/ but I can't figure out the Ruby construct to replace each instance one by one. I can't use .gsub() because that will match every instance on the line, and replace every array declaration with whatever the first one was. .scan() complains that the string is being modified if you try and use scan with a .sub()! inside a block. Any ideas would be appreciated!

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• What exactly is a variable in C++?

  - by FredOverflow

  The standard says A variable is introduced by the declaration of an object. The variable's name denotes the object. But what does this definition actually mean? Does a variable give a name to an object, i.e. are variables just a naming mechanism for otherwise anonymous objects? Or is a variable the name itself? Or is a variable a named object in the sense that every variable is also an object? Or is a variable just a "proxy" with a name that "delegates" all operations to the real object? To confuse things further, many C++ books seem to treat variables and objects as synonyms. What is your take on this?

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• 'Loading' web page for async call

  - by Sieg

  I have a simple web page in ASP.NET / C#. Currently to fully render the data I require calling a block of code that runs on background threads and can take multiple minutes to complete. I've got it to the point (using the async attribute on the page declaration) to execute and return fine with the html once it's done. What I'd like it to do is allow me to return immediately with a 'loading page' of some sort and then have that page be updated when the background work has been completed. Right now I get nothing on the page while the background work is being processed. Any ideas on the best way or clever way to do that would greatly be appreciated! Thanks, Sieg

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• Correct approach to validate attributes of an instance of class

  - by systempuntoout

  Having a simple Python class like this: class Spam(object): __init__(self, description, value): self.description = description self.value = value Which is the correct approach to check these constraints: "description cannot be empty" "value must be greater than zero" Should i: 1.validate data before creating spam object ? 2.check data on __init__ method ? 3.create an is_valid method on Spam class and call it with spam.isValid() ? 4.create an is_valid static method on Spam class and call it with Spam.isValid(description, value) ? 5.check data on setters declaration ? 6.... Could you recommend a well designed\Pythonic\not verbose (on class with many attributes)\elegant approach?

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• How to get rid of `deprecated conversion from string constant to ‘char*’` warnings in GCC?

  - by Josh Matthews

  So I'm working on an exceedingly large codebase, and recently upgraded to gcc 4.3, which now triggers this warning: warning: deprecated conversion from string constant to ‘char*’ Obviously, the correct way to fix this is to find every declaration like char *s = "constant string"; or function call like void foo(char *s); foo("constant string"); and make them const char pointers. However, that would mean touching 564 files, minimum, which is not a task I wish to perform at this point in time. The problem right now is that I'm running with -werror, so I need some way to stifle these warnings. How can I do that?

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• How to split the definition of template friend funtion within template class?

  - by ~joke

  The following example compiles fine but I can't figure out how to separate declaration and definition of operator<<() is this particular case. Every time I try to split the definition friend is causing trouble and gcc complains the operator<<() definition must take exactly one argument. #include <iostream> template <typename T> class Test { public: Test(const T& value) : value_(value) {} template <typename STREAM> friend STREAM& operator<<(STREAM& os, const Test<T>& rhs) { os << rhs.value_; return os; } private: T value_; }; int main() { std::cout << Test<int>(5) << std::endl; }

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• Xcode method navigation

  - by Bill

  In Xcode 4, I can press Ctrl-6 to get a list of all the methods in the current file. The problem is, if I have private methods declared at the top of my implementation file, say: @interface Foo () -(void)tap:(id)sender; @end @implementation Foo ... -(void)tap:(id)sender { ... } then starting to type "tap" while the method list is visible will just take me to the declaration, since it comes first in the file, when what I really want is the implementation. Is there any way to exclude these declarations from the method list or do I need to resort to separate Foo.h and Foo+Private.h headers? Thanks!

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• C++ how to make typedefs globally visible

  - by user231536

  I have a typedef typedef unsigned int my_type; used in a file. I would like to make it visible across all my files, without putting it in a header file included by everything. I don't want to go the header file route because as it stands this will be the only declaration in the header file (and it seems unnecessary to add a file just for this). Is there a way to do this? If instead I had: typedef X my_type; where X was a class, would I need to include X.h everywhere and have the typedef at the end of X.h ?

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• C++ Declaring an uninitialized variable without a null constructor

  - by xbonez

  Consider the DUPoint class, whose declaration appears below. Assume this code appears in a file named DUPoint.h: #include <string> class DUPoint { public: DUPoint (int x, int y); int getX () const; int getY () const; void setX (int x); void setY (int y); void print(); private: int x_; int y_; }; Is it true that you cannot declare an uninitialized DUPoint variable with a statement such as DUPoint P; using this class as currently configured because it has no null constructor?

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• xsl:variable xsl:copy-of select

  - by user1901345

  I have the following XML: Picture 1 Picture 2 Picture 3 While this XSL does what is expected (output the attr of the first picture): It seems to be not possible to do the same inside the variable declaration using xsl:copy-of: Curious: If I just select "$FirstPicture" instead of "$FirstPicture/@attr" in the second example, it outputs the text node of Picture 1 as expected... Before you all suggest me to rewrite the code: This is just a simplified test, my real aim is to use a named template to select a node into the variable FirstPicture and reuse it for further selections. I hope someone could help me to understand the behavior or could suggest me a proper way to select a node with code which could be easily reused (the decission which node is the first one is complex in my real application). Thanks.

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• C: Why does gcc allow char array initialization with string literal larger than array?

  - by Ashwin

  int main() { char a[7] = "Network"; return 0; } A string literal in C is terminated internally with a nul character. So, the above code should give a compilation error since the actual length of the string literal Network is 8 and it cannot fit in a char[7] array. However, gcc (even with -Wall) on Ubuntu compiles this code without any error or warning. Why does gcc allow this and not flag it as compilation error? gcc only gives a warning (still no error!) when the char array size is smaller than the string literal. For example, it warns on: char a[6] = "Network"; [Related] Visual C++ 2012 gives a compilation error for char a[7]: 1>d:\main.cpp(3): error C2117: 'a' : array bounds overflow 1> d:\main.cpp(3) : see declaration of 'a'

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