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  • Partial template specialization: matching on properties of specialized template parameter

    - by Kenzo
    template <typename X, typename Y> class A {}; enum Property {P1,P2}; template <Property P> class B {}; class C {}; Is there any way to define a partial specialization of A such that A<C, B<P1> > would be A's normal template, but A<C, B<P2> > would be the specialization? Replacing the Y template parameter by a template template parameter would be nice, but is there a way to partially specialize it based on P then? template <typename X, template <Property P> typename Y> class A {}; // template <typename X> class A<X,template<> Y<P2> > {}; <-- not valid Is there a way by adding traits to a specialization template<> B<P2> and then using SFINAE in A?

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  • Binder and variadic template ends up in a segmentation fault

    - by phlipsy
    I wrote the following program #include <iostream> template<typename C, typename Res, typename... Args> class bind_class_t { private: Res (C::*f)(Args...); C *c; public: bind_class_t(Res (C::*f)(Args...), C* c) : f(f), c(c) { } Res operator() (Args... args) { return (c->*f)(args...); } }; template<typename C, typename Res, typename... Args> bind_class_t<C, Res, Args...> bind_class(Res (C::*f)(Args...), C* c) { return bind_class<C, Res, Args...>(f, c); } class test { public: int add(int x, int y) { return x + y; } }; int main() { test t; // bind_class_t<test, int, int, int> b(&test::add, &t); bind_class_t<test, int, int, int> b = bind_class(&test::add, &t); std::cout << b(1, 2) << std::endl; return 0; } compiled it with gcc 4.3.3 and got a segmentation fault. After spending some time with gdb and this program it seems to me that the addresses of the function and the class are mixed up and a call of the data address of the class isn't allowed. Moreover if I use the commented line instead everything works fine. Can anyone else reproduce this behavior and/or explain me what's going wrong here?

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  • Higher order function « filter » in C++

    - by Red Hyena
    Hi all. I wanted to write a higher order function filter with C++. The code I have come up with so far is as follows: #include <iostream> #include <string> #include <functional> #include <algorithm> #include <vector> #include <list> #include <iterator> using namespace std; bool isOdd(int const i) { return i % 2 != 0; } template < template <class, class> class Container, class Predicate, class Allocator, class A > Container<A, Allocator> filter(Container<A, Allocator> const & container, Predicate const & pred) { Container<A, Allocator> filtered(container); container.erase(remove_if(filtered.begin(), filtered.end(), pred), filtered.end()); return filtered; } int main() { int const a[] = {23, 12, 78, 21, 97, 64}; vector<int const> const v(a, a + 6); vector<int const> const filtered = filter(v, isOdd); copy(filtered.begin(), filtered.end(), ostream_iterator<int const>(cout, " ")); } However on compiling this code, I get the following error messages that I am unable to understand and hence get rid of: /usr/include/c++/4.3/ext/new_allocator.h: In instantiation of ‘__gnu_cxx::new_allocator<const int>’: /usr/include/c++/4.3/bits/allocator.h:84: instantiated from ‘std::allocator<const int>’ /usr/include/c++/4.3/bits/stl_vector.h:75: instantiated from ‘std::_Vector_base<const int, std::allocator<const int> >’ /usr/include/c++/4.3/bits/stl_vector.h:176: instantiated from ‘std::vector<const int, std::allocator<const int> >’ Filter.cpp:29: instantiated from here /usr/include/c++/4.3/ext/new_allocator.h:82: error: ‘const _Tp* __gnu_cxx::new_allocator<_Tp>::address(const _Tp&) const [with _Tp = const int]’ cannot be overloaded /usr/include/c++/4.3/ext/new_allocator.h:79: error: with ‘_Tp* __gnu_cxx::new_allocator<_Tp>::address(_Tp&) const [with _Tp = const int]’ Filter.cpp: In function ‘Container<A, Allocator> filter(const Container<A, Allocator>&, const Predicate&) [with Container = std::vector, Predicate = bool ()(int), Allocator = std::allocator<const int>, A = const int]’: Filter.cpp:30: instantiated from here Filter.cpp:23: error: passing ‘const std::vector<const int, std::allocator<const int> >’ as ‘this’ argument of ‘__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> > std::vector<_Tp, _Alloc>::erase(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, __gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >) [with _Tp = const int, _Alloc = std::allocator<const int>]’ discards qualifiers /usr/include/c++/4.3/bits/stl_algo.h: In function ‘_FIter std::remove_if(_FIter, _FIter, _Predicate) [with _FIter = __gnu_cxx::__normal_iterator<const int*, std::vector<const int, std::allocator<const int> > >, _Predicate = bool (*)(int)]’: Filter.cpp:23: instantiated from ‘Container<A, Allocator> filter(const Container<A, Allocator>&, const Predicate&) [with Container = std::vector, Predicate = bool ()(int), Allocator = std::allocator<const int>, A = const int]’ Filter.cpp:30: instantiated from here /usr/include/c++/4.3/bits/stl_algo.h:821: error: assignment of read-only location ‘__result.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = const int*, _Container = std::vector<const int, std::allocator<const int> >]()’ /usr/include/c++/4.3/ext/new_allocator.h: In member function ‘void __gnu_cxx::new_allocator<_Tp>::deallocate(_Tp*, size_t) [with _Tp = const int]’: /usr/include/c++/4.3/bits/stl_vector.h:150: instantiated from ‘void std::_Vector_base<_Tp, _Alloc>::_M_deallocate(_Tp*, size_t) [with _Tp = const int, _Alloc = std::allocator<const int>]’ /usr/include/c++/4.3/bits/stl_vector.h:136: instantiated from ‘std::_Vector_base<_Tp, _Alloc>::~_Vector_base() [with _Tp = const int, _Alloc = std::allocator<const int>]’ /usr/include/c++/4.3/bits/stl_vector.h:286: instantiated from ‘std::vector<_Tp, _Alloc>::vector(_InputIterator, _InputIterator, const _Alloc&) [with _InputIterator = const int*, _Tp = const int, _Alloc = std::allocator<const int>]’ Filter.cpp:29: instantiated from here /usr/include/c++/4.3/ext/new_allocator.h:98: error: invalid conversion from ‘const void*’ to ‘void*’ /usr/include/c++/4.3/ext/new_allocator.h:98: error: initializing argument 1 of ‘void operator delete(void*)’ /usr/include/c++/4.3/bits/stl_algobase.h: In function ‘_OI std::__copy_move_a(_II, _II, _OI) [with bool _IsMove = false, _II = const int*, _OI = const int*]’: /usr/include/c++/4.3/bits/stl_algobase.h:435: instantiated from ‘_OI std::__copy_move_a2(_II, _II, _OI) [with bool _IsMove = false, _II = __gnu_cxx::__normal_iterator<const int*, std::vector<const int, std::allocator<const int> > >, _OI = __gnu_cxx::__normal_iterator<const int*, std::vector<const int, std::allocator<const int> > >]’ /usr/include/c++/4.3/bits/stl_algobase.h:466: instantiated from ‘_OI std::copy(_II, _II, _OI) [with _II = __gnu_cxx::__normal_iterator<const int*, std::vector<const int, std::allocator<const int> > >, _OI = __gnu_cxx::__normal_iterator<const int*, std::vector<const int, std::allocator<const int> > >]’ /usr/include/c++/4.3/bits/vector.tcc:136: instantiated from ‘__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> > std::vector<_Tp, _Alloc>::erase(__gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >, __gnu_cxx::__normal_iterator<typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer, std::vector<_Tp, _Alloc> >) [with _Tp = const int, _Alloc = std::allocator<const int>]’ Filter.cpp:23: instantiated from ‘Container<A, Allocator> filter(const Container<A, Allocator>&, const Predicate&) [with Container = std::vector, Predicate = bool ()(int), Allocator = std::allocator<const int>, A = const int]’ Filter.cpp:30: instantiated from here /usr/include/c++/4.3/bits/stl_algobase.h:396: error: no matching function for call to ‘std::__copy_move<false, true, std::random_access_iterator_tag>::__copy_m(const int*&, const int*&, const int*&)’ Please tell me what I am doing wrong here and what is the correct way to achieve the kind of higher order polymorphism I want. Thanks.

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  • Best intro to C++ static metaprogramming?

    - by jwfearn
    Static metaprogramming (aka "template metaprogramming") is a great C++ technique that allows the execution of programs at compile-time. A light bulb went off in my head as soon as I read this canonical metaprogramming example: #include <iostream> using namespace std; template< int n > struct factorial { enum { ret = factorial< n - 1 >::ret * n }; }; template<> struct factorial< 0 > { enum { ret = 1 }; }; int main() { cout << "7! = " << factorial< 7 >::ret << endl; // 5040 return 0; } If one wants to learn more about C++ static metaprogramming, what are the best sources (books, websites, on-line courseware, whatever)?

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  • C++ Template Classes Circular Dependency Problem

    - by TomWij
    We have two classes: template<typename T, typename Size, typename Stack, typename Sparse> class Matrix and template<typename T, typename Size> class Iterator Matrix should be able to return begin and end iterators and Iterator will keep a referrence to the Matrix to access the elements via it's interface. We don't want Iterator to depend on the internal storage of the Matrix to prevent coupling. How can we solve this cyclic dependency problem? (The internal Storage class has the same template parameters as the Matrix class and the same access procedures as the Matrix itself)

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  • Template metaprogram converting type to unique number

    - by daramarak
    I just started playing with metaprogramming and I am working on different tasks just to explore the domain. One of these was to generate a unique integer and map it to type, like below: int myInt = TypeInt<AClass>::value; I want to know if this is at all possible, and in that case how. Because although I have learned much about exploring this subject I still have failed to come up with an answer. (P.S. A yes/no answer is much more gratifying than a c++ solution that doesn't use metaprogramming, as this is the domain that I am exploring)

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  • razor websites not working and all dlls are present

    - by Michael Tot Korsgaard
    I've uploaded a .cshtml website to a surftown server, and I got some problems running the code. But I have a problem with it running the Razor code. This is how the page renders:(Default.cshtml) I've already checked for internal communication problems. And this is my result: But then why isn't it working, and how can I fix it? I've heard that it can be a problem with views but how whould I fix this if that's the case? My websites folder tree: (And some files too) App_Code App_Data packages Microsoft.AspNet.Razor.2.0.20710.0 Microsoft.Asp.Net.WebPages.2.0.20710.0 Microsoft.Asp.Net.WebPages.Administration.2.0.20710.0 Microsoft.Asp.Net.WebPages.Data.2.0.20710.0 Microsoft.Asp.Net.WebPages.WebData.2.0.20710.0 Microsoft.Web.Infrastructure.1.0.0.0 NuGet.Core.1.6.2 bin packages jQuery.2.0.3 Content Scripts Tools Microsoft.AspNet.Mvc.4.0.30506.0 lib net40 Microsoft.AspNet.Razor.2.0.30506.0 lib net40 Microsoft.AspNet.WebPages.2.0.30506.0 lib net40 Pages Chapters Read.cshtml Edit Move Chapter.cshtml Entry.cshtml Entries EnterEntry.cshtml EnterNote.cshtml Login Login.cshtml Search Result.cshtml Scripts Addons TinyMCE Styles CSS Views _Layout.cshtml Default.cshtml My web.config file looks like this: <?xml version="1.0"?> <configuration> <system.web> <compilation debug="true" targetFramework="4.0"> <buildProviders> <add extension=".cshtml" type="System.Web.WebPages.Razor.RazorBuildProvider, System.Web.WebPages.Razor"/> </buildProviders> <assemblies> <add assembly="System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> </assemblies> </compilation> </system.web> <connectionStrings> <add connectionString="database connection" providerName="System.Data.SqlClient"/> </connectionStrings> </configuration> EDIT: Is it a problem that all my files are .cshtml?

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  • Policy-based template design: How to access certain policies of the class?

    - by dehmann
    I have a class that uses several policies that are templated. It is called Dish in the following example. I store many of these Dishes in a vector (using a pointer to simple base class), but then I'd like to extract and use them. But I don't know their exact types. Here is the code; it's a bit long, but really simple: #include <iostream> #include <vector> struct DishBase { int id; DishBase(int i) : id(i) {} }; std::ostream& operator<<(std::ostream& out, const DishBase& d) { out << d.id; return out; } // Policy-based class: template<class Appetizer, class Main, class Dessert> class Dish : public DishBase { Appetizer appetizer_; Main main_; Dessert dessert_; public: Dish(int id) : DishBase(id) {} const Appetizer& get_appetizer() { return appetizer_; } const Main& get_main() { return main_; } const Dessert& get_dessert() { return dessert_; } }; struct Storage { typedef DishBase* value_type; typedef std::vector<value_type> Container; typedef Container::const_iterator const_iterator; Container container; Storage() { container.push_back(new Dish<int,double,float>(0)); container.push_back(new Dish<double,int,double>(1)); container.push_back(new Dish<int,int,int>(2)); } ~Storage() { // delete objects } const_iterator begin() { return container.begin(); } const_iterator end() { return container.end(); } }; int main() { Storage s; for(Storage::const_iterator it = s.begin(); it != s.end(); ++it){ std::cout << **it << std::endl; std::cout << "Dessert: " << *it->get_dessert() << std::endl; // ?? } return 0; } The tricky part is here, in the main() function: std::cout << "Dessert: " << *it->get_dessert() << std::endl; // ?? How can I access the dessert? I don't even know the Dessert type (it is templated), let alone the complete type of the object that I'm getting from the storage. This is just a toy example, but I think my code reduces to this. I'd just like to pass those Dish classes around, and different parts of the code will access different parts of it (in the example: its appetizer, main dish, or dessert).

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  • How do I apply a "template" or "skeleton" of code in C# here?

    - by Scott Stafford
    In my business layer, I need many, many methods that follow the pattern: public BusinessClass PropertyName { get { if (this.m_LocallyCachedValue == null) { if (this.Record == null) { this.m_LocallyCachedValue = new BusinessClass( this.Database, this.PropertyId); } else { this.m_LocallyCachedValue = new BusinessClass( this.Database, this.Record.ForeignKeyName); } } return this.m_LocallyCachedValue; } } I am still learning C#, and I'm trying to figure out the best way to write this pattern once and add methods to each business layer class that follow this pattern with the proper types and variable names substituted. BusinessClass is a typename that must be substituted, and PropertyName, PropertyId, ForeignKeyName, and m_LocallyCachedValue are all variables that should be substituted for. Are attributes usable here? Do I need reflection? How do I write the skeleton I provided in one place and then just write a line or two containing the substitution parameters and get the pattern to propagate itself? EDIT: Modified my misleading title -- I am hoping to find a solution that doesn't involve code generation or copy/paste techniques, and rather to be able to write the skeleton of the code once in a base class in some form and have it be "instantiated" into lots of subclasses as the accessor for various properties. EDIT: Here is my solution, as suggested but left unimplemented by the chosen answerer. // I'll write many of these... public BusinessClass PropertyName { get { return GetSingleRelation(ref this.m_LocallyCachedValue, this.PropertyId, "ForeignKeyName"); } } // That all call this. public TBusinessClass GetSingleRelation<TBusinessClass>( ref TBusinessClass cachedField, int fieldId, string contextFieldName) { if (cachedField == null) { if (this.Record == null) { ConstructorInfo ci = typeof(TBusinessClass).GetConstructor( new Type[] { this.Database.GetType(), typeof(int) }); cachedField = (TBusinessClass)ci.Invoke( new object[] { this.Database, fieldId }); } else { var obj = this.Record.GetType().GetProperty(objName).GetValue( this.Record, null); ConstructorInfo ci = typeof(TBusinessClass).GetConstructor( new Type[] { this.Database.GetType(), obj.GetType()}); cachedField = (TBusinessClass)ci.Invoke( new object[] { this.Database, obj }); } } return cachedField; }

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  • Sticky footer with CSS Layout Template Module?

    - by boris callens
    I'm currently looking into the JQuery library for CSS Layout Template module Is it possible to define the height of a placeholder with *? Meaning it will push content down if it has to, or fill up any remaining space if the complete content is less then the view port. This would be really nice to make the whole sticky footer thing much easier and robust.

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  • Template operator linker error

    - by Dani
    I have a linker error I've reduced to a simple example. The build output is: debug/main.o: In function main': C:\Users\Dani\Documents\Projects\Test1/main.cpp:5: undefined reference tolog& log::operator<< (char const (&) [6])' collect2: ld returned 1 exit status It looks like the linker ignores the definition in log.cpp. I also cant put the definition in log.h because I include the file alot of times and it complains about redefinitions. main.cpp: #include "log.h" int main() { log() << "hello"; return 0; } log.h: #ifndef LOG_H #define LOG_H class log { public: log(); template<typename T> log &operator <<(T &t); }; #endif // LOG_H log.cpp: #include "log.h" #include <iostream> log::log() { } template<typename T> log &log::operator <<(T &t) { std::cout << t << std::endl; return *this; }

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  • Template class giving linker error ...

    - by Atul
    Hi, I am having a template class which is exposed, in which I added a method. This class is in namespace A. Now, I am calling this method in another namespace (say B). Initially, compiler gave me linker error saying "unresolved external symbol" for this particular method. However, if I call this method inside the same namespace (that is A), it links well. After that, it links well in namespace B as well. Why could this be happening ? Does this has something to do with the creating Template object of my class ? Atul

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  • wpf error template - red box still visible on collapse of an expander

    - by Andy Clarke
    Hi, I'm doing some validation on the DataSource of TextBox that's within an Expander and have found that once a validation error has been triggered, if I collapse the Expander, the red box stays where the TextBox would have been. <Expander Header="Blah Blah Blah"> <TextBox Name="TextBox" Validation.ErrorTemplate="{DynamicResource TextBoxErrorTemplate}" Text="{Binding Path=Blah, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}" /> </Expander> I've tried to get round this by binding the visibility of the Error Template to the Expander, however I think there's something wrong with the binding. <local:NotVisibleConverter x:Key="NotVisibleConverter" /> <ControlTemplate x:Key="TextBoxErrorTemplate"> <DockPanel> <Border BorderBrush="Red" BorderThickness="2" Visibility="{Binding Path=IsExpanded, Converter={StaticResource NotVisibleConverter}, RelativeSource={RelativeSource AncestorType=Expander}}" > <AdornedElementPlaceholder Name="MyAdorner" /> </Border> </DockPanel> <ControlTemplate.Triggers> <Trigger Property="Validation.HasError" Value="true"> <Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors)[0].ErrorContent}"/> </Trigger> </ControlTemplate.Triggers> </ControlTemplate> I guess I've gone wrong with my binding, can someone put me back on track please? Alternatively does anyone know another solution to the ErrorTemplate still being visible on the collapse of an Expander?

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  • Why does gcc think that I am trying to make a function call in my template function signature?

    - by nieldw
    GCC seem to think that I am trying to make a function call in my template function signature. Can anyone please tell me what is wrong with the following? 227 template<class edgeDecor, class vertexDecor, bool dir> 228 vector<Vertex<edgeDecor,vertexDecor,dir>> Graph<edgeDecor,vertexDecor,dir>::vertices() 229 { 230 return V; 231 }; GCC is giving the following: graph.h:228: error: a function call cannot appear in a constant-expression graph.h:228: error: template argument 3 is invalid graph.h:228: error: template argument 1 is invalid graph.h:228: error: template argument 2 is invalid graph.h:229: error: expected unqualified-id before ‘{’ token Thanks a lot.

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  • How to detect whether there is a specific member variable in class?

    - by Kirill V. Lyadvinsky
    For creating algorithm template function I need to know whether x or X (and y or Y) in class that is template argument. It may by useful when using my function for MFC CPoint class or GDI+ PointF class or some others. All of them use different x in them. My solution could be reduces to the following code: template<int> struct TT {typedef int type;}; template<class P> bool Check_x(P p, typename TT<sizeof(&P::x)>::type b = 0) { return true; } template<class P> bool Check_x(P p, typename TT<sizeof(&P::X)>::type b = 0) { return false; } struct P1 {int x; }; struct P2 {float X; }; // it also could be struct P3 {unknown_type X; }; int main() { P1 p1 = {1}; P2 p2 = {1}; Check_x(p1); // must return true Check_x(p2); // must return false return 0; } But it does not compile in Visual Studio, while compiling in the GNU C++. With Visual Studio I could use the following template: template<class P> bool Check_x(P p, typename TT<&P::x==&P::x>::type b = 0) { return true; } template<class P> bool Check_x(P p, typename TT<&P::X==&P::X>::type b = 0) { return false; } But it does not compile in GNU C++. Is there universal solution? UPD: Structures P1 and P2 here are only for example. There are could be any classes with unknown members.

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  • Setting up Subsonic 3.0 on a ASP.NET web application on Visual Studio 2008

    - by Rob Paul
    I followed the steps on this tutorial video by at subsonic website. Everything seems to be self explanatory but when I copy the .tt files into my Visual Studio nothing happens. I have read other question relating to this problem on this website but they don't seem to fix this problem. I also went into the regedit to find out the generator key for .tt files and it is properly set. This is not a visual studio express or anything but a professional edition also I am trying to build a ASP.net web application and not a MVC application like the demo. Any help will be greatly appreciated. Thank You

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  • Explicit specialization in non-namespace scope

    - by Mark
    template<typename T> class CConstraint { public: CConstraint() { } virtual ~CConstraint() { } template <typename TL> void Verify(int position, int constraints[]) { } template <> void Verify<int>(int, int[]) { } }; Compiling this under g++ gives the following error: Explicit specialization in non-namespace scope 'class CConstraint' In VC, it compiles fine. Can anyone please let me know the workaround?

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  • Get the signed/unsigned variant of an integer template parameter without explicit traits

    - by Blair Holloway
    I am looking to define a template class whose template parameter will always be an integer type. The class will contain two members, one of type T, and the other as the unsigned variant of type T -- i.e. if T == int, then T_Unsigned == unsigned int. My first instinct was to do this: template <typename T> class Range { typedef unsigned T T_Unsigned; // does not compile public: Range(T min, T_Unsigned range); private: T m_min; T_Unsigned m_range; }; But it doesn't work. I then thought about using partial template specialization, like so: template <typename T> struct UnsignedType {}; // deliberately empty template <> struct UnsignedType<int> { typedef unsigned int Type; }; template <typename T> class Range { typedef UnsignedType<T>::Type T_Unsigned; /* ... */ }; This works, so long as you partially specialize UnsignedType for every integer type. It's a little bit of additional copy-paste work (slash judicious use of macros), but serviceable. However, I'm now curious - is there another way of determining the signed-ness of an integer type, and/or using the unsigned variant of a type, without having to manually define a Traits class per-type? Or is this the only way to do it?

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  • Can I suppress newlines with Django's template engine?

    - by ento
    In Rails ERB, you can suppress newlines by adding a trailing hyphen to tags: <ul> <% for @item in @items -%> <li><%= @item %></li> <% end -%> </ul> becomes: <ul> <li>apple</li> <li>banana</li> <li>cacao</li> </ul> Is there a way to do this in Django? (Disclosure: I'm generating a csv file with Django)

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  • Need help with auto-scaffolding template in ASP.NET MVC

    - by DanM
    I'm trying to write an auto-scaffolder for Index views. I'd like to be able to pass in a collection of models or view-models (e.g., IQueryable<MyViewModel>) and get back an HTML table that uses the DisplayName attribute for the headings (th elements) and Html.Display(propertyName) for the cells (td elements). Each row should correspond to one item in the collection. Here's what I have so far: <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl" %> <% var items = (IQueryable<TestProj.ViewModels.TestViewModel>)Model; // Should be generic! var properties = items.First().GetMetadata().Properties .Where(pm => pm.ShowForDisplay && !ViewData.TemplateInfo.Visited(pm)); %> <table> <tr> <% foreach(var property in properties) { %> <th> <%= property.DisplayName %> </th> <% } %> </tr> <% foreach(var item in items) { %> <tr> <% foreach(var property in properties) { %> <td> <%= Html.Display(property.DisplayName) %> // This doesn't work! </td> <% } %> </tr> <% } %> </table> Two problems with this: I'd like it to be generic. So, I'd like to replace var items = (IQueryable<TestProj.ViewModels.TestViewModel>)Model; with var items = (IQueryable<T>)Model; or something to that effect. The <td> elements are not working because the Html in <%= Html.Display(property.DisplayName) %> contains the model for the view, which is a collection of items, not the item itself. Somehow, I need to obtain an HtmlHelper object whose Model property is the current item, but I'm not sure how to do that. How do I solve these two problems?

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  • Template error with django-photologue: 'Permission Denied'

    - by Ellie P.
    I'm in the process of re-setting up my Django development environment after reinstalling my OS. We use django-photologue with our project, which I installed using easy_install. However, I'm getting a template error on every template that has a photologue photo: TemplateSyntaxError at /newsroom/news/ Caught an exception while rendering: (13, 'Permission denied') One example of the line where the error is located: <img src="{{ photo.get_list_url }}"> I'm totally stumped--I've used photologue for this project on many different platforms and have never had this problem. Google yields nothing. I'm currently using Jolicloud (based on Ubuntu Jaunty). I'm working with a pre-existing database, so all of the photo sizes and everything have already been set up.

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  • Display value of a django form field in a template?

    - by Eran Kampf
    I have a form with an email property. When using {{ form.email }} in case of some validation error, django still renders the previous value in the input tag's value attribute: <input type="text" id="id_email" maxlength="75" class="required" value="[email protected]" name="email"> I want to render the input tag myself (to add some javascript code and an error class in case of an error). For example this is my template instead of {{ form.email }}: <input type="text" autocomplete="on" id="id_email" name="email" class="email {% if form.email.errors %}error{% endif %}"> However this does not display the errorneous value ("[email protected]" in this example) to the user. How do I get the field's value in the template?

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  • "Inherited" types using CRTP and typedef

    - by Ken Moynihan
    The following code does not compile. I get an error message: error C2039: 'Asub' : is not a member of 'C' Can someone help me to understand this? Tried VS2008 & 2010 compiler. template <class T> class B { typedef int Asub; public: void DoSomething(typename T::Asub it) { } }; class C : public B<C> { public: typedef int Asub; }; class A { public: typedef int Asub; }; int _tmain(int argc, _TCHAR* argv[]) { C theThing; theThing.DoSomething(C::Asub()); return 0; }

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  • django generic view not recieving an object (template issue?)

    - by Kirby
    My Model class Player(models.Model): player_name = models.CharField(max_length=50) player_email = models.CharField(max_length=50) def __unicode__(self): return self.player_name My Root urls.py urlpatterns = patterns('', (r'^kroster/', include('djangosite.kroster.urls')), (r'^admin/(.*)', admin.site.root), ) My kroster urls.py from djangosite.kroster.models import Player info_dict = { 'queryset': Player.objects.all(), } urlpatterns = patterns('', (r'^$', 'django.views.generic.list_detail.object_list', info_dict), (r'^(?P<object_id>\d+)/$', 'django.views.generic.list_detail.object_detail', info_dict), ) My player_list.html template <h1>Player List</h1> {% if error_message %}<p><strong>{{ error_message }}</strong></p>{% endif %} <ul> {% for player in object.player_set.all %} <li id="{{ player.id }}">{{ forloop.counter }} .)&nbsp;&nbsp;{{ player }}</li> {% endfor %} </ul> Sadly my template output is this. <h1>Player List</h1> <ul> </ul> Apologies if this is a stupid mistake. It has to be something wrong w/ my template.

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  • How to check if a variable exists in a FreeMarker template?

    - by Don
    Hi, I have a Freemarker template which contains a bunch of placeholders for which values are supplied when the template is processed. I want to conditionally include part of the template if the userName variable is supplied, something like: [#if_exists userName] Hi ${userName}, How are you? [/#if_exists] However, the FreeMarker manual seems to indicate that if_exists is deprecated, but I can't find another way to achieve this. Of course, I could simple providing an additional boolean variable isUserName and use that like this: [#if isUserName] Hi ${userName}, How are you? [/#if] But if there's a way of checking whether userName exists then I can avoid adding this extra variable. Cheers, Don

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