As discussed in DConf2015: Python-like keyword arguments

[Atila Neves via Digitalmars-d]

On Thursday, 28 May 2015 at 22:35:14 UTC, Atila Neves wrote:
> I might do a blog post on this, but here's some POC code:

Now with default values!


import std.stdio;
import std.range;
import std.typetuple;
import std.traits;
import std.conv;

struct Foo { int i; }
struct Bar { int i; }
struct Baz { int i; }

void func(Foo foo = Foo(11), Bar bar = Bar(22), Baz baz = 
Baz(33)) {
     writeln("foo is ", foo);
     writeln("bar is ", bar);
     writeln("baz is ", baz);
}

void main() {
     kwargs!func(Bar(2), Baz(3), Foo(1)); //1, 2, 3
     kwargs!func(Baz(3), Foo(1)); //1, 22, 3
}

auto getStrArgs(alias F, T...)() {
     string[] strArgs;

     foreach(i, ParamType; ParameterTypeTuple!F) {
         enum index = staticIndexOf!(ParamType, T);

         static if(index != -1) {
             strArgs ~= "args[" ~ index.to!string ~ "]";
         } else {
             alias defaultValue = ParameterDefaultValueTuple!F[i];
             static if(is(defaultValue == void)) {
                 strArgs ~= ParamType.stringof ~ ".init";
             } else {
                 strArgs ~= defaultValue.stringof;
             }
         }
     }

     return strArgs;
}

auto kwargs(alias F, T...)(T args) {
     enum strArgs = getStrArgs!(F, T);
     mixin("return F(" ~ strArgs.join(",") ~ ");");
}