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DblQt
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 Posted: Thu Jan 29, 2004 3:09 pm Post subject: Specialzation of Template Member Functions. |
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Hi,
I wonder whether it is possible to specialize certain member functions
instead of whole templates.
Example:
<code>
template<class T, bool b> Example {
public:
T* m_instance;
// Implementation should be dependent on b.
void DoSomething();
};
template<class T, bool b> void Example<T, true>::DoSomething() {
// Execute special code that has to be provided by T
// Delegate must be defined in T
m_instance->Delegate();
}
template<class T, bool b> void Example<T, false>::DoSomething() {
// Execute code that is not special to T.
}
</code>
This is similar to what I've tried to do. Of course this is not a
complete definition and can't be a correct implementation either since
it doesn't compile. I'm wondering whether something like this is
possible at all.
Kind Regrads
Stefan
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xueweizhong
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| Posted: Fri Jan 30, 2004 9:35 am Post subject: Re: Specialzation of Template Member Functions. |
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template <class T, bool b>
struct Example
{
void DoSomething();
};
------------------------------------------#t1
template<class T>
void Example<T, true>::DoSomething();
------------------------------------------#1
template<class T>
void Example<T, false>::DoSomething();
------------------------------------------#2
in the context of #t1
both #1 && #2 are partial specialization of #3:
template <class T, bool b>
void Example<T, b>::DoSomething();
------------------------------------------#3
because #3 is a member function template,
and BY C++98
functon template can't be partial specialized,
^^^^^^^
so that #1 && #2 is illegal.
Note that the following program is OK:
template <class T, bool b>
struct Example
{
void DoSomething();
};
template <>
void Example<bool, true>::DoSomething()
{
}
int main()
{
Example<bool, true> a;
a.DoSomething();
}
BUT if you provides the specialization of template class:
template <class T, bool b>
struct Example<T, false> { /*...*/ };
------------------------------------------#t2
template <class T>
struct Example<T, true> { /*....*/ };
------------------------------------------#t3
then, #1 becomes the member function template of #t2
and #2 becomes the member function template of #t3
now, #1, #2 is not partial specialization of #3,
they are different class-template (#t2#t3)'s member function.
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Dhruv
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| Posted: Fri Jan 30, 2004 9:37 am Post subject: Re: Specialzation of Template Member Functions. |
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On Thu, 29 Jan 2004 10:09:16 -0500, DblQt wrote:
| Quote: | Hi,
I wonder whether it is possible to specialize certain member functions
instead of whole templates.
|
No. partial specialization of functions is not permitted.
Regards,
-Dhruv.
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Martijn Lievaart
Guest
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| Posted: Thu Feb 05, 2004 11:38 am Post subject: Re: Specialzation of Template Member Functions. |
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On Thu, 29 Jan 2004 10:09:16 -0500, DblQt wrote:
| Quote: | Hi,
I wonder whether it is possible to specialize certain member functions
instead of whole templates.
Example:
code
template<class T, bool b> Example {
public:
T* m_instance;
// Implementation should be dependent on b.
void DoSomething();
};
template<class T, bool b> void Example<T, true>::DoSomething() {
// Execute special code that has to be provided by T
// Delegate must be defined in T
m_instance->Delegate();
}
template<class T, bool b> void Example<T, false>::DoSomething() {
// Execute code that is not special to T.
}
/code
This is similar to what I've tried to do. Of course this is not a
complete definition and can't be a correct implementation either since
it doesn't compile. I'm wondering whether something like this is
possible at all.
|
// Not sure if this compiles, but the basic idea is there
template<class T, bool b> Example {
template<bool b> struct X;
template<> struct X<true> {
X(T *p) { p->delegate(); }
};
template<> struct X<false> {
X(T *p) {}
};
public:
T* m_instance;
// Implementation should be dependent on b.
void DoSomething() { X<b>(); }
};
HTH,
M4
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Martijn Lievaart
Guest
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| Posted: Fri Feb 06, 2004 12:33 pm Post subject: Re: Specialzation of Template Member Functions. |
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On Thu, 05 Feb 2004 06:38:28 -0500, Martijn Lievaart wrote:
| Quote: | public:
T* m_instance;
// Implementation should be dependent on b.
void DoSomething() { X<b>(); }
|
Oopsa:
void DoSomething() { X<b>(m_instance); }
M4
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