On Tuesday, 19 July 2016 at 15:55:02 UTC, Rufus Smith wrote:
I have some functions that take other functions. I would like
the attributes to be able to "fall" through so I get overload
like behavior. I only care that I am passing a function, not if
it is shared, extern(C), pure, @nogc, etc.
void foo(R, A...)(R function(A) bar)
{
alias type = typeof(bar);
pragma(msg, type);
// does magic with bar
}
foo never uses the attributes of bar explicitly. It uses type
to instantiate other functions like bar. I have to create a foo
for each attribute combination, which is not worth while. The
code seems to break only for extern, the best I can tell, most
attributes do pass through. But type does not contain these
attributes.
You shall do something like this (please note that I didn't check
the docs while writing this; you shall definitely have a look at
std.traits and consider the following as pseudo-code and not
actual D):
void foo(Fun)(Fun bar)
if (isSomeFunction!Fun) // your constraint that bar is a
function
{
// how to get your R and A types, if you need them:
alias R = ReturnType!bar;
alias A = Parameters!bar;
alias type = Fun;
pragma(msg, type);
// do some magic
}