Re: template template parameter compilation errors!!!
aaragon wrote:
On Mar 21, 4:57 pm, Ian Collins <ian-n...@hotmail.com> wrote:
aaragon wrote:
Hello guys,
I got a Mac and I'm trying to compile my code on Mac OS using GCC 4.3.
My code used to compile just fine in Ubuntu with the same compiler but
now it's giving me errors in all template template parameter code.
Anyone has an idea why this is happening???
The error message looks like the following:
element.h:494: error: type/value mismatch at argument 1 in template
parameter list for 'template<template<class, class> class MapPolicy>
class fea::TriangleGaussMap'
element.h:494: error: expected a template of type 'template<class,
class> class MapPolicy', got 'template<class _Key, class _Tp, class
_Compare, class _Alloc> class std::map'
Without the full code it looks like you are not providing enough
template parameters in your declaration. std::map takes 4 parameters
and you only appear to be providing 4.
Older compilers where a bit lax when it cam to enforcing this and the
exactly matching requirements may be relaxed in the forthcoming
standard. For now, you have to provide the same number of template
parameters.
*Please* don't quote signatures!
What about default parameters? I could use for that class template
either the std::map, or a hash_map. They both have different number of
parameters, so why should I provide the total number of parameters?
I don't think there is a simple solution. Your only option appears to
be to partially specialise hash_map to reduce the number of parameters.
Something like
#include <map>
#include <hash_map>
template <typename ItemType,
typename KeyType,
template <typename E,
typename K,
typename P = std::less<E>,
typename A = std::allocator<std::pair<const K,E> > >
class C>
struct X
{
C<ItemType,KeyType> c;
};
template <typename T>
struct Hash
{
bool operator()( const T&, const T&) const;
};
template <typename V,
typename K,
typename Compare = std::less<KeyType>,
typename Alloc = std::allocator<std::pair<const K,V> > >
struct HashMap : public std::hash_map<V,K,Hash<K>,Compare,Alloc>
{
using hash_map<V,K,Hash<K>,Compare,Alloc>::operator[];
};
int main()
{
X<int,int,std::map> m;
X<int,int,std::multimap> mm;
X<int,int,HashMap> hm;
return 0;
}
--
Ian Collins.