Re: How to get template parameter, when i match a template?
On Jun 30, 4:52 pm, Kai-Uwe Bux <jkherci...@gmx.net> wrote:
abir wrote:
I am matching a template, and specializing based of a template, rather
than a single class.
The codes are like,
template<template<typename T,typename Alloc = std::allocator<T>
class C>
class pix{
};
template<>
class pix<vector>{
};
The matching works perfectly.
Now how will i get the template parameters in the specialized class?
I want to do things like,
template<>
class pix<std::vector>{
private:
std::vector<T>* v_;
};
Why a pointer to a vector. That looks fishy.
From where will I get T & Alloc fro which it is a match?
You won't get them from anywhere. You have to supply them.
BTW: this is not related to the class being specialized. If you consider the
unspecialized pix, you will find that you cannot get at T and Alloc either
because they are just placeholders for something you still need to specify.
Best
Kai-Uwe Bux
It can be reference to a vector instead of pointer. I want to have an
external iterator kind of thing, which i name pix, which is portable,
i.e can be stored as long as the element at the location exists,
irrespective of whether container resizes or not. (Of course they can
be made immune to pop_front,push_front, insert, erase etc also)
The pointer to a vector is not at all fishy in this case, almost all
(not all) iterators has a pointer to the container.
I want something like,
typedef vector<int> V;
V v; v.push_back() a few elements ...
pix<V> p(v);
++p; *p; get element
v.push_back() a few more.
*p to get element.
so for a container C , i wanted pix as,
template<typename C>
class pix{
C& c_;
C::size_type index_;
};
when C is a vector, but another implementation for another C. Only
problem is C itself is a template.
Why the template template parameters are "just placeholders" when the
instance is a full class?
Any other way to do it?
Thanks
abir