Re: Issue with typeof

[Moritz Maxeiner via Digitalmars-d-learn]

On Monday, 20 March 2017 at 17:58:32 UTC, Moritz Maxeiner wrote:
2) Create a template that can be used like this (you'll want to 
consult std.traits for this):

void foo (delegateOf!(T.method) fptr) {}

This may sound harder that it is, btw. A template that does 
exactly that is the following (template constraints that verify 
`method` to actually be a member method left out):

template DelegateTypeOf(alias method)
{
    import std.array : replaceFirst;
    import std.string : format;

    enum fnType = typeof(&method).stringof;
    enum dgType = fnType.replaceFirst("function", "delegate");

    mixin(`alias DelegateTypeOf = %s;`.format(dgType));
}

Including the above, a full example would be the following:

interface T
{
    void method(int x);
}

void foo(DelegateTypeOf!(T.method) dg)
{
    dg(42);
}

class X : T
{
    void method(int x)
    {
        import std.stdio : writefln;
        writefln("Hello, world #%d!", x);
    }
}

void main()
{
    T t = new X;
    foo(&t.method);
}