• Ender KaShae <astrothayne gmail.com> Jul 28 2007
• "Jarrett Billingsley" <kb3ctd2 yahoo.com> Jul 28 2007

Ender KaShae <astrothayne gmail.com> writes:

I have two questions concerning functions and delegates (as they are so similar
I will refer to them simply as functions from now on)  1.) can you specify a
template argument to be a function and 2.) can you have arrays of functions

1.) when I try template t(type: function) I get an error, but there must be
some way to specify that you need the type to be a function

2.) in an example in the docs it says that arrays of functions are invalid
types in c++ and d, however i've used arrays of function pointers in c++ and it
seems strange that such a type would be invalid, a function pointer is after
all just a pointer

"Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:

"Ender KaShae" <astrothayne gmail.com> wrote in message 
news:f8ghug$5bg$1 digitalmars.com...

 1.) when I try template t(type: function) I get an error, but there must 
 be some way to specify that you need the type to be a function


template Templ(T : U function(V), U, V...)
{

}

void main()
{
    mixin Templ!(int); // fails
    mixin Templ!(void function(int, float)); // OK
}

:)

 2.) in an example in the docs it says that arrays of functions are invalid 
 types in c++ and d, however i've used arrays of function pointers in c++ 
 and it seems strange that such a type would be invalid, a function pointer 
 is after all just a pointer


There's a slight difference.  A function pointer is valid in both languages, 
but a function type is illegal.  It's very difficult to get at a function 
type in D, but possible.  Consider:

typedef void Foo();
Foo[] f;

typedef void function() Bar;
Bar[] g;

Notice that the first defines Foo as a function -- not function _pointer_ --  
type.  Foo[] f; fails.  But the second defines Bar as a function pointer, 
and Bar[] g is fine.