Re: Call method with Variant array as parameters

[Timoses via Digitalmars-d-learn]

On Saturday, 14 July 2018 at 11:08:21 UTC, Andre Pany wrote:

Hi,

I have a class with methods and I want to call a method by using a variant array. The length of the array and the types exactly fits the method signature.

In the last line of main you see the coding which should be generated. I need some coding which looks at the signature of bar and uses this information

to create "(args[0].get!string, args[1].get!long)".

I think it is possible with string mixins, but is there some better way?

Maybe a staticMap?

class Foo
{
    void bar(string s, long l) {}
}

void main()
{
    import std.variant: Variant;

    Foo foo = new Foo();

    Variant[] args = [Variant("Hello"), Variant(42)];

__traits(getMember, foo, "bar")(args[0].get!string, args[1].get!long);

}

Kind regards
André

How about this?


import std.variant: Variant;
import std.traits : isCallable;

class Foo
{
    void bar(string s, long l)
    {
        import std.stdio : writeln;
        writeln(s); writeln(l);
    }
}

void call(T)(T fun, in Variant[] args)
         if (isCallable!fun)
{
    import std.traits : Parameters;
    alias Params = Parameters!fun;

    Params params;
    static foreach(i, param; params)
    {
        if (auto p = args[i].peek!(Params[i]))
        {
                param = *p;
        }
        // perhaps create a warning if peeking was unsuccessful...
    }
    fun(params);
}

unittest
{
    Foo foo = new Foo();
    Variant[] args = [Variant("Hello"), Variant(42L)];
    call(&foo.bar, args);
}