A "general" tag

[Marco Leise]

Am Mon, 16 Apr 2012 20:52:16 +0200
schrieb "Xan" <xancorreu at gmail.com>:

> Uf!, it's more than I can process....
> It's really a **complicated** thing to do that in D.

Too much information, yes. Too complicated no. :)
D is statically typed (Fantom allows both static and dynamic typing). That means that for every variable in your program you know beforehand what type it is. You say you have String, Type and Obj. Here we cannot say what type Obj is, because it depends on what Type says. Now you want something from a statically typed language, that it wasn't designed for.

You may want to adapt to the style of a statically typed language and use a struct:

import std.datetime;

struct Person {
	string name;  // a person has a field 'name' of type string
	Date   date;
}

This means that you cannot change the type of 'date' or 'name', and you cannot have a person without a date.

If you really, *really*, REALLY need the full flexibility, you can use Variants. You can store any data in a Variant, so it would replace Type and Obj in your code.

struct Tag {
	string description; // <String>: store "name", "date", etc. in this
	Variant data;       // <Type & Obj>: store "John" or Date(2012, 4, 25) in this
}

Many more solutions are possible, but we'd need to take a look at your code. Also one solution may be more flexible while another is faster. It depends a bit on what you expect. Every language has its pros and cons. Dynamic typing is not one of D's strengths, but execution speed is, for example.

-- 
Marco