From: Dave Burt <dave@...>
Date: 2005-10-15T12:01:58+09:00
Subject: Re: Factory function like Array() for your own classes

Sean O'Halpin:
> I was quite surprised today to find out that you can define both a
> class and a function with the same name and still be able to reference
> them both separately.
>
> This makes it possible to define factory functions that work like the
> built-in Array() and String() functions, e.g. so that Thing(1,2,3) is
> the same as Thing.new(1,2,3).
> ...
> So... what do you think?

In Ruby, so we're told, methods begin with a lower-case letter. Now, 
actually, you can have all kinds of funky names:
irb> class Object
irb> define_method("!@#%$") { 43 }
irb> end
=> #<Proc:0x02b46bd0@(irb):16>
irb> send("!@#%$")
43

I think we don't often see these is because methods _should_ begin in 
lower-case.

That said, as Ara has pointed out, there are 4 such methods in the core, and 
at least one more in the standard library (Rational()). But these methods 
are all cast methods - you feed them something that isn't an Array, Integer, 
Float, String, Rational, and it gives you either an object of the correct 
type or an error.

I suppose that part of your Thing example could be seen as a cast from a 
hash to a Thing, but taking a block is a bit of a stretch. Why not just use 
..new? Why does new need an alias?

Cheers,
Dave