template and forward declaration

[jobseeker]

From: jobseeker95479@ yahoo.com (jobseeker)
Newsgroups: comp.lang.c++.m oderated
Subject: template and forward declaration
NNTP-Posting-Host: 131.233.150.22

I have defined a class that contains a data member of a function type.
The signature of the function type take a pointer of the class itself
as a parameter:

class Softkey; // forward declaration

typedef int (* pfncOnSelect)(S oftkey *key, void *);

class Softkey
{

...
int value;
pfncOnSelect m_OnSelect;
...
};

This class is compiled and run successfully without error. The
problem I have now is that I am trying to modify this class into a
templated class as follows:

template<class Type>
class SoftKey; // forward declaration.

typedef int (* pfncOnSelect)(S oftKey *key, void *);

template<class Type>
class Softkey
{

...
Type value;
pfncOnSelect m_OnSelect;
...
};

Now the compiler complains about syntax error in the typedef line.
I have tried with

template<class Type>
typedef int (* pfncDrawCap)(Te stKey *key, void *);

or

template<class Type>
typedef int (* pfncDrawCap)(Te stKey<Type> *key, void *);

but I still get an error. Can anyone throw some light into this?

[Julián Albo]

Re: template and forward declaration

jobseeker escribió:
[color=blue]
> I have tried with
>
> template<class Type>
> typedef int (* pfncDrawCap)(Te stKey *key, void *);
>
> or
>
> template<class Type>
> typedef int (* pfncDrawCap)(Te stKey<Type> *key, void *);
>
> but I still get an error. Can anyone throw some light into this?[/color]

The language does not allow templatized typedef. You can do something
like:

template <class Type>
struct DrawCap {
typedef int (* pfnc) (TestKey <Type> * key, void *);
};

And use the type DrawCap::pfnc.

Regards.

[DarkSpy]

Re: template and forward declaration

Julián Albo <JULIANALBO@ter ra.es> wrote in message news:<3F8C73C1. B3A384EA@terra. es>...[color=blue]
> jobseeker escribi :
>[color=green]
> > I have tried with
> >[/color]
>[color=green]
> > template<class Type>
> > typedef int (* pfncDrawCap)(Te stKey *key, void *);
> >[/color]
>[color=green]
> > or
> >[/color]
>[color=green]
> > template<class Type>
> > typedef int (* pfncDrawCap)(Te stKey<Type> *key, void *);
> >[/color]
>[color=green]
> > but I still get an error. Can anyone throw some light into this?[/color]
>
> The language does not allow templatized typedef. You can do something
> like:
>
> template <class Type>
> struct DrawCap {
> typedef int (* pfnc) (TestKey <Type> * key, void *);
> };
>
> And use the type DrawCap::pfnc.[/color]

the current is: DrawCap<Type>:: pfnc; for ex:
DrawCap<int>::p fnc
[color=blue]
>
> Regards.[/color]