template<typename ClassT>
struct ParentClass
{
template<typename T>
static int Get(ClassT *p, gmThread *a_thread, gmVariable *a_operands, size_t a_offset) { return 1; }
//////////////////////////////////////////////////////////////////////////
template<>
static int Get<bool>(ClassT *p, gmThread *a_thread, gmVariable *a_operands, size_t a_offset)
{
// do stuff with bool type
return 1;
}
template<>
static int Get<int>(ClassT *p, gmThread *a_thread, gmVariable *a_operands, size_t a_offset)
{
// do stuff with int type
return 1;
}
template<>
static int Get<float>(ClassT *p, gmThread *a_thread, gmVariable *a_operands, size_t a_offset)
{
// do stuff with float type
return 1;
}
}
template help please(c++)
Author
Can someone help me out with some template issues I'm having.
I have this struct for a script binding interface that I have some explicit specialized function inside of.
This compiles and works as I expect in MSVC2005, but not in GCC 4.1.0
GCC gives the error:
error: explicit specialization in non-namespace scope 'struct ParentClass<ClassT>'
error: enclosing class templates are not explicitly specialized
errot: 'Get' is not a function template
I don't quite understand how to change this to do it 'correctly' despite some digging around on google and such.
Here it is trimmed up a bit.
You cannot specialize template inside a class, only in a namespace. MVS does allows for such specialization, but GCC is more correct.
Just move Get outside of class.
Just move Get outside of class.
template<typename ClassT, typename T>static int Get(ClassT *p, gmThread *a_thread, gmVariable *a_operands, size_t a_offset) { return 1; }template<typename ClassT>static int Get<ClassT, bool>(ClassT *p, gmThread *a_thread, gmVariable *a_operands, size_t a_offset){ // do stuff with bool type return 1;}// and so on
Author
Hmm, error C2768: 'Get' : illegal use of explicit template arguments
edit:
should it be this?
checking in gcc to see, this compiles in msvc at least. will report back
edit:
should it be this?
template<typename ClassT, typename T>static int Get(ClassT *p, gmThread *a_thread, gmVariable *a_operands, size_t a_offset) { return 1; }template<typename ClassT, bool>static int Get(ClassT *p, gmThread *a_thread, gmVariable *a_operands, size_t a_offset){ // do stuff with bool type return 1;}checking in gcc to see, this compiles in msvc at least. will report back
Author
ok yea that doesn't work.
Grr, not sure how to accomplish what I need to do.
I don't see why this has to be so difficult. Standards or not something that seems like it should be a simple matter turns into a raging pain as soon as I bring GCC into it.
Basically I need to explicitly specialize a set of functions that also takes another templated class type as an argument, as shown. Any ideas?
Grr, not sure how to accomplish what I need to do.
I don't see why this has to be so difficult. Standards or not something that seems like it should be a simple matter turns into a raging pain as soon as I bring GCC into it.
Basically I need to explicitly specialize a set of functions that also takes another templated class type as an argument, as shown. Any ideas?
Create a template-class complete with a specialisation for bool. Each should have a templated static member function that does the actual work.
Then (optionally) create a templated wrapper function that forwards to the right specialisation.
Example:
Then (optionally) create a templated wrapper function that forwards to the right specialisation.
Example:
template<typename T>struct gizmo{ template<typename U> static void apply( /* ... */ );};template<>struct gizmo<bool>{ template<typename U> static void apply( /* ... */ );};template<typename T, typename U>void convenient_wrapper_function( /* ... */ ){ gizmo<T>::apply<U>( /* ... */ ); // ^ // might need "template" key word in here, // I can never remember!?}Quote:Original post by Nitage
IIRC, it isn't legal to partially specialize a function template.
Yes, I was thinking of classes, it's what I had to deal with.
Still, I'm no longer sure about this, there appears to be a bug in gcc as well, that applies to this problem.
Personally, I solved the problem by avoiding partial specialization of this type altogether, didn't think it was worth dealing with it further.
Since these functions don't appear to depend on ParentClass<T> in any way (only on T), why nest the functions in the first place?
Author
It wasn't necessary for ParentClass to be there. I was using it more like a namespace than a struct. The code you pasted compiled in MSVC2005, until I added a version for float and std::string, etc. I should be able to get away with passing a void* instead of ClassT *. Internally the functions are setting/getting a <T> type based on the address + offset, so I don't think I think a void * will do just as well. That failing, I'll try the method the_edd posted, though that would require a number of other changes if it comes to that.
Thanks everyone for the help.
Thanks everyone for the help.
This topic is closed to new replies.
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