[Issue 17714] New: Function template - this T for static methods

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17714

          Issue ID: 17714
           Summary: Function template - this T for static methods
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Windows
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: timosesu at gmail.com

For static method templates the this T will not work to deduce the calling
derived class/interface.

Although this information is present at compile-time, there seems to be no way
to easily access the calling derived class:


interface I
{
    static void test(this T)()
    {
        writeln(T.type.stringof);
    }
}

abstract class A
{
    static void test(this T)()
    {
        writeln(T.type.stringof);
    }
}

class B : A
{
    alias type = uint;
}
class C : I {
    alias type = int;
}

void main() {
    B.test();
    C.test();
}

Throws:
  Error: template app.A.test cannot deduce function from argument types !()(),
candidates are:
        app.A.test(this T)()
  Error: template app.I.test cannot deduce function from argument types !()(),
candidates are:
        app.I.test(this T)()


Shouldn't it be possible to access the class which is calling the static method
as easily as "this T" as template parameter? Would "this T" be too confusing,
as it is a static method and this does not really exist?

To simplify, the following should be possible in some way (if not via "this
T"):

class A
{
    // T will be whatever class is calling this method
    static void func (this T)() { };
}

A.func();


Possibly related issue:
https://issues.dlang.org/show_bug.cgi?id=14191

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