Can't use map (and friends) for virtual functions?
Andrej Mitrovic
none at none.none
Mon Apr 25 16:44:43 PDT 2011
import std.algorithm;
struct Foo
{
int bar(string) { return 1; }
void run()
{
auto result = map!(bar)(["test"]);
}
}
void main()
{
}
D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\algorithm.d(128): Error: this for bar needs to be type Foo not type Map!(bar,string[])
I can't use a virtual function as an alias parameter to a template, it either has to be a free function or a static function.
So basically I have to use delegates:
import std.algorithm;
import std.traits;
import std.stdio;
auto myMap(Delegate, Range)(Delegate dg, Range t)
{
ReturnType!(dg)[] result;
foreach (val; t)
{
result ~= dg(val);
}
return result;
}
struct Foo
{
int bar(string) { return 1; }
void run()
{
auto result = myMap(&bar, ["test", "test"]);
writeln(result);
}
}
void main()
{
auto foo = Foo();
foo.run();
}
But this means I have to take every Phobos function which I need and which takes an alias and convert it to a delegate version if I ever want to use it inside a struct or a class for non-static functions.
Can't Phobos functions be made smarter so they work with virtual functions? Or would "alias" need re-engineering?
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