On 08/27/2012 05:05 AM, Walter Bright wrote:
On 8/26/2012 6:55 PM, Timon Gehr wrote:
On 08/27/2012 02:44 AM, Walter Bright wrote:
On 8/26/2012 4:50 PM, Timon Gehr wrote:
On 08/27/2012 12:41 AM, Walter Bright wrote:
The trouble for function pointers, is that any default args would need
to be part of the type, not the declaration.
They could be made part of the variable declaration.
You mean part of the function pointer variable?
Yes.
Consider what you do with a function pointer - you pass it to someone
else. That someone else gets it as a type, not a declaration.
If it is a template function, yes. But then you may as well pass the
function pointer variable per alias, which is common.
You pass the function declaration by alias, not the function pointer
declaration. In which case you will get the default arguments.
The function declaration is not necessarily available and the
pointer/delegate might not be a constant. This is the point of function
pointers and delegates.
Otherwise someone else gets nothing but a parameter declaration.
I.e. you lose the default argument information, since that is not
attached to the
type.
I think most valid existing use cases would still be supported:
int execFunctionPointer(int function(int = 2) fun){
return fun();
}
auto dg = (int x, int y=2){ return x+y; }
writeln(range.map!dg());
int function(int=3)[] funs;
funs[0]();
It is up to you if it is worth the effort, of course.
and it falls apart immediately once you try to transfer that function
pointer anywhere.
No it does not. The examples people have posted where it breaks their
code that I am aware of all would work with this scheme.
What possible use case do you think would have to be supported by
function pointer/delegate default arguments that cannot be supported
without serious implementation problems?
