On Wednesday, 6 June 2018 at 06:25:49 UTC, DaggetJones wrote:
Hi, I'm wondering how I should approach supplying
functions/delegates around in D. I have option of using classes
where the function exists inside the class and to provide
different functionality different classes are created.
Alternatively I could just pass the function directly around
without all the weight of the class.
This led me to wonder if there is a way to combine the two
methods?
With D's alias this would it be possible to have the user code
treat the function as a delegate but define the functions
actually in a class without any restrictions?
import std.stdio;
alias MyFunction = int delegate();
class MyFunctor
{
alias func this;
int MyData = 5;
int func() { return MyData; }
}
void bar(MyFunction foo) { writeln(foo()); }
void main()
{
MyFunctor f = new MyFunctor();
bar(&f.func);
// but not
// bar(f); or bar(&f);
}
But I would like to simply pass the class as if it were the
member func, which is what the alias this is suppose to provide.
It seems D ignores the alias this in this case?
You'll need to provide a function that returns func. The way it's
currently written, the alias this would basically translate to
bar(f.func()):
class MyFunctor
{
alias func2 this;
int MyData = 5;
int func() { return MyData; }
auto func2() { return &func; }
}
--
Simen
