Hello,
I can't compile this piece of code:
> struct Object
> {
>     void run(wstring ending, uint index)(int number)
>     {
> 
>     }
> }
> 
> void tester(alias callback, T)(int number, T object = null)
> {
>     static if(is(T == typeof(null))) alias handler = callback;
>     else auto handler(wstring ending, uint index) = object.callback!(ending, index);
>         	handler!("rfv", 5)(word);
> }
> 
> void main()
> {
>     Object obj;
>     tester!(Object.run)(10, &obj);
> }

Here in tester I want to alias a template method and call it on object if this object isn't null. But I don't understand how to do it.
How to solve the problem?

On Sun, 18 Aug 2019 19:17:16 +0000, Andrey wrote:

> Here in tester I want to alias a template method and call it on object
> if this object isn't null. But I don't understand how to do it.
> How to solve the problem?

I don't think you can alias an object method directly; three methods I know of:

---
struct Struct {
    void run(int number) {
        import std.stdio;
        writeln("run ", number);
    }
}

// Pass the object itself.
void func1(alias obj)(int number) if (isFunction!(obj.run)) {
    obj.run(number);
}

// Pass the object and the name of the method.
void func2(alias obj, string method)(int number)
        if (__traits(compiles, "obj." ~ method ~ "(number);"))
{
    mixin("obj." ~ method ~ "(number);");
}

// Pass the method at runtime.
void func3(void delegate(int) f, int number) {
    f(number);
}

void main() {
    Struct obj;
    func1!(obj)(1);
    func2!(obj, "run")(2);
    func3(&obj.run, 3);
}
---

Also, you don't want to name something "Object"; the base class is called Object -- the struct shadows it but you may run into some bug or confusion later.

--Ryan