On Sat, 16 Oct 2010 11:57:36 -0400, Steven Schveighoffer
<schvei...@yahoo.com> wrote:
On Sat, 16 Oct 2010 11:22:43 -0400, Juanjo Alvarez <f...@fakeemail.com>
wrote:
On Sat, 16 Oct 2010 14:42:13 +0000 (UTC), dsimcha <dsim...@yahoo.com>
wrote:
delegate with minimal overhead. This mitigates the situation a
lot, since if an
API requires a delegate and you have a function pointer, you just
do a
toDelegate(someFunctionPointer).
Sorry for asking here something that should go to D.learn, but how do
you do the reverse, that is, getting a function from a delegate? I need
that in my project so I can pass it to signal so some Unix signal will
trigger a method of an already instantiated object.
auto dg = &obj.method;
auto fptr = dg.funcptr;
auto context = dg.ptr;
Note, you cannot call fptr, you will get a runtime error.
Here is the related documentation (search for funcptr):
http://www.digitalmars.com/d/2.0/function.html
I believe there may be in phobos a type which wraps a function pointer
into a delegate. Not sure if it was ever added though...
-Steve
Actually, you can use funcptr for simple functions. Here's an example how:
void main(string[] args) {
auto foo = (int x){ writeln(x); };
void function(int,void*) bar = foo.funcptr;
bar(5,foo.ptr);
foo(5);
return;
}
Structs larger than 8 bytes require a hidden return pointer, so instead of
LargeStruct function(int,void*) bar;
you'd have
void function(int,LargeStruct*,void*) bar;
However, if Unix code needs to call the function, it needs to do so using
the C calling conventions, which are platform/compiler specific.
