Workaround for lack of templated typedef

[zr]

Hi,

My original intent was to use the following code:

template <typename T> // compilation error: at typedef template is
illegal
typedef (*FunctionType)(T*,T const*,T const*,T const*,T const*, int
const*);

template <typename T, FunctionType f>
class foo
{
....
}

but the compiler complained about no templated typedef allowed.

Instead i am using the following not so aesthetic code:
template <typename T, (*f)(T*,T const*,T const*,T const*,T const*, int
const*)>
class foo
{
....
}

Now each class that inherits from foo will have this horrific template
declaration.
Is there any better way to do this?

 

[peter koch]

Hi,

My original intent was to use the following code:

template <typename T> // compilation error: at typedef template is
illegal
typedef (*FunctionType)(T*,T const*,T const*,T const*,T const*, int
const*);

template <typename T, FunctionType f>
class foo
{
...

}

but the compiler complained about no templated typedef allowed.

Instead i am using the following not so aesthetic code:
template <typename T, (*f)(T*,T const*,T const*,T const*,T const*, int
const*)>
class foo
{
...

}

Now each class that inherits from foo will have this horrific template
declaration.
Is there any better way to do this?

You could use

template< typename T >
struct func
{
typedef void (*ttype)(T const*); // or whatever
};

and then use func<T>::ttype instead of the typedef.

/Peter

 

[zr]

You could use

template< typename T >
struct func
{
   typedef void (*ttype)(T const*); // or whatever

};

and then use func<T>::ttype instead of the typedef.

/Peter

Peter, thank you.

 

[Noah Roberts]

You could use

template< typename T >
struct func
{
typedef void (*ttype)(T const*); // or whatever
};

and then use func<T>::ttype instead of the typedef.

/Peter

Well, not exactly. It's kind of hard to say what was intended by the OP
since the code is wrong. However, if there was a return type in the
function it would be correct. If we then traded your version for the
OP's it would actually accomplish different things.

Your version creates a typedef "ttype" that is a pointer to function
type. The OP's creates a template that requires an address to a
function of that signature and calls it "f".

Sounds like the OP needed what yours does, but it should be noted that
they don't accomplish the same thing at all.