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sandor
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 Posted: Sun Mar 27, 2005 2:23 am Post subject: class template specialization question |
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Hi,
I have a template class defined in a holy unchangeable library. I would
like to specialize some methods of this class for every type T, where
Pred<T>::r == 1
In pseudo-code:
--- holy_library.h ----
template <typename T>
class Example
{
void f()
{
print( "This should be called for general T types" );
}
};
--- client.h ----
#include "library.h"
template <typename T>
class Pred
{
enum { r = notRelevantForThisQuestion };
};
template < ??? >
void Example < ??? >::f()
{
print( "This should be called for T types where Pred<T>::r == 1" );
};
Is there any way to do this in client.h? No changes are allowed to
holy_library.h
thanks,
Sandor
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
[ comp.lang.c++.moderated. First time posters: Do this! ]
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Maxim Yegorushkin
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| Posted: Mon Mar 28, 2005 1:35 am Post subject: Re: class template specialization question |
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On 26 Mar 2005 21:23:31 -0500, sandor <sandor.hojtsy (AT) gmail (DOT) com> wrote:
| Quote: | Hi,
I have a template class defined in a holy unchangeable library. I would
like to specialize some methods of this class for every type T, where
Pred<T>::r == 1
In pseudo-code:
--- holy_library.h ----
template <typename T
class Example
{
void f()
{
print( "This should be called for general T types" );
}
};
--- client.h ----
#include "library.h"
template
class Pred
{
enum { r = notRelevantForThisQuestion };
};
template < ???
void Example < ??? >::f()
{
print( "This should be called for T types where Pred<T>::r == 1" );
};
Is there any way to do this in client.h? No changes are allowed to
holy_library.h
|
Just add another level of abstraction. Do not use Example directly, proxy
it, for example:
template <typename T>
struct Pred
{
enum { r = 0 };
};
template <typename T>
struct Pred<T*>
{
enum { r = 1 };
};
template<class T, int C = Pred
struct ExampleProxy : Example<T>
{
};
template<class T>
struct ExampleProxy<T, 1>
{
void f(); // here is your f()
};
--
Maxim Yegorushkin
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
[ comp.lang.c++.moderated. First time posters: Do this! ]
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