templates

C++, what does this syntax mean?

i found this in this file: http://www.boost.org/doc/libs/1_43_0/boost/spirit/home/phoenix/core/actor.hpp What does this syntax means? struct actor ... { ... template <typename T0, typename T1> typename result<actor(T0&,T1&)>::type // this line I know what typename and templates are, my question is about actor(...

XSL template structure for choosing latest event.

I have a list grouped by Region and it currently shows all the items for each city. I want to reduce to only the most recent advisory for each city. I have tried to use an xsl:for-each statement but I am messing up the names/parameters. List is called mlc The list contains the fields: Title City Region Advisory DateCreated TT (calcula...

C++ Using a class template argument as a template argument for another type

Hey Everyone, I'm having this problem while writing my own HashTable. It all works, but when I try to templatize the thing, it gave me errors. I recreated the problem as follows: THIS CODE WORKS: typedef double Item; class A { public: A() { v.push_back(pair<string, Item>("hey", 5.0)); } void iterate() { ...

Displaying Category Articles in Joomla Home page

Hi guys, I am wondering about displaying categories in home page. I have 5 different categories under 1 section. And All categories have as many articles as they have. Now I want to show the category title and its few articles in home page... I am not sure about which module or component to use OR can we do it self? ...

Can a custom MFC window/dialog be a class template instantiation?

There's a bunch of special macros that MFC uses when creating dialogs, and in my quick tests I'm getting weird errors trying to compile a template dialog class. Is this likely to be a big pain to achieve? Here's what I tried: MyDlg.h template <class W> class CMyDlg : public CDialog { typedef CDialog super; DECLARE_DYNAMIC(CMyD...

Determining whether a class implements a generic list in a T4 template

I'm writing a T4 template which loads some classes from an assembly, does some analysis of the classes and then generates some code. One particular bit of analysis I need to do is to determine whether the class implements a generic list. I can do this pretty simply in C#, e.g. public class Foo : List<string> { } var t = typeof(Foo); ...

Template operator linker error

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....

Conditional type definitions

I'm sure that boost has some functions for doing this, but I don't know the relevant libraries well enough. I have a template class, which is pretty basic, except for one twist where I need to define a conditional type. Here is the psuedo code for what I want struct PlaceHolder {}; template <typename T> class C{ typedef (T == P...

Template Class – Symbols not found

I've seen a few related posts, but I can't really make sense of what I need to do to fix a program I'm making for my entry-level C++ class. My errors are: Build Final Project of project Final Project with configuration Debug Ld "build/Debug/Final Project" normal x86_64 cd "/Users/nick/Dropbox/|Syncs/Xcode/Final Project" setenv MACOSX...

Template specialization to use default type if class member typedef does not exist

Hi Everyone, I'm trying to write code that uses a member typedef of a template argument, but want to supply a default type if the template argument does not have that typedef. A simplified example I've tried is this: struct DefaultType { DefaultType() { printf("Default "); } }; struct NonDefaultType { NonDefaultType() { print...

What is causing this template-related compile error? (c++)

When I try to compile this: #include <map> #include <string> template <class T> class ZUniquePool { typedef std::map< int, T* > ZObjectMap; ZObjectMap m_objects; public: T * Get( int id ) { ZObjectMap::const_iterator it = m_objects.find( id ); if( it == m_objects.end() ) ...

Django dictionary in templates: Grab key from another objects attribute

I have a dictionary called number_devices I'm passing to a template, the dictionary keys are the ids of a list of objects I'm also passing to the template (called implementations). I'm iterating over the list of objects and then trying to use the object.id to get a value out of the dict like so: {% for implementation in implementat...

Forcing images to not wrap

I can't touch the html theme but I have access to the css files. <div class="photos"> <img src="a.jpg" alt="" align="left" /> <img src="b.jpg" alt="" align="left" /> <img src="c.jpg" alt="" align="left" /> //align makes the images wrap </div> Unfortunately I can't remove align="left" from the images otherwise this CSS sn...

Do I need multiple template specializations if I want to specialize for several kinds of strings?

For example: template<typename T> void write(T value) { mystream << value; } template<> void write<const char*>(const char* value) { write_escaped(mystream, value); } template<> void write<char*>(char* value) { write_escaped(mystream, value); } template<> void write<const std::string&>(const std::string& value) { writ...

C++ template member specialization - is this a compiler limitation?

Is it possible to do this kind of specialization? If so, how? The specialization in question is marked //THIS SPECIALIZATION WILL NOT COMPILE I have used VS2008, VS2010, gcc 4.4.3 and neither can compile this. I know i can avoid this by overloading func but i want to know if there is a way to do this with template specialization. (impr...

Using template parameters as template parameters

Why is the following code invalid? template <typename S, typename T> struct B{ void f(T t, S s) {t.f<S>(s); } }; gcc 4.3.4 complains that it "expected primary-expression before '>' token", i.e. that "S" wasn't a valid primary-expression. ...

Obtain container type from (its) iterator type in C++ (STL)

It is easy given a container to get the associated iterators, example: std::vector<double>::iterator i; //An iterator to a std::vector<double> I was wondering if it is possible, given an iterator type, to deduce the type of the "corresponding container" (here I am assuming that for each container there is one and only one (non-const) ...

Why does this class declaration not work on Visual Studio

So I'm trying to get some code that is written for gcc to compile on Visual Studio 2008. I have a problem that I have narrowed down to this: class value_t { public: typedef std::deque<value_t> sequence_t; typedef sequence_t::iterator iterator; }; This code fails: 1>cpptest.cpp 1>c:\program files\microsoft visual st...

Can I write a test that succeeds if and only if a statement does not compile?

I'd like to prevent clients of my class from doing something stupid. To that end, I have used the type system, and made my class only accept specific types as input. Consider the following example (Not real code, I've left off things like virtual destructors for the sake of example): class MyDataChunk { //Look Ma! Implementation! };...

Academic question: typename

Possible Duplicate: Why do I need to use typedef typename in g++ but not VS? Hi, recently I accounted with a "simple problem" of porting code from VC++ to gcc/intel. The code is compiles w/o error on VC++: #include <vector> using std::vector; template <class T> void test_vec( std::vector<T> &vec) { typedef std::ve...