From: Nat Pryce <nat.pryce@...13media.com>
Date: 2002-10-31T01:33:47+09:00
Subject: Re: feature idea: custom literals

I see.  I think this is pretty superfluous, and also dramatically
reduces the legibility of the code, especially if <x,y,z> creates one
type of object in one file and and another type of object in another.

You can achieve a similar effect with functions, but also control
legibility of code.  At the very least, you only have to use one extra
character, at best you'd have a readable constructor function.

E.g:

# Some classes:

class Color
	def initialize( r, g, b )
		@r = r
		@g = g
		@b = b
	end
	attr_reader :r
	attr_reader :g
	attr_reader :b
end

class Vector
	def initialize( x, y, z )
		@x = x
		@y = y
		@z = z
	end
	attr_reader :x
	attr_reader :y
	attr_reader :z
end

# Some "literal" functions

def Vector( x, y, z )
	Vector.new( x, y, z )
end

ORIGIN = Vector(0,0,0)

def Color( r, g, b )
	Color.new( r, g, b )
end

BLACK = Color(0,0,0)
RED = Color(1,0,0)
GREEN = Color(0,1,0)
BLUE = Color(0,0,1)
WHITE = Color(1,1,1)


# Or use abreviations:

def Vec( x, y, z )
	Vector.new( x, y, z )
end

def V( x, y, z )
	Vector.new( x, y, z )
end

X_AXIS = V(1,0,0)

def RGB( r, g, b )
	Color.new( r, g, b )
end

CYAN = RGB(0,1,1)


This idiom is used by Ruby already, for example the Integer and String
functions.

Cheers,
	Nat.

On Wed, 2002-10-30 at 16:04, Nikodemus Siivola wrote:
> On Thu, 31 Oct 2002, Nat Pryce wrote:
> 
> > How would you import a literal definition?  If you define it in a file,
> > can it only be used within a file?  Or can it be imported into another
> > file (by the require statement for example)?
> 
> Pseudocode, assuming that only '<' ... '>' literals are user definable:
> 
> in vector.rb:
> 
> class Vector
>   def initialize x,y,z
>     @x, @y, z = x, y, z
>   end
> end
> 
> in sample.rb:
> 
> require 'vector'
> literal Vector.new
> <0,1,2>
> # Is equivalent to Vector.new (0,1,2), but only in this file
> # and only until it is (possibly) redefined
> 
> So custom literals would be per file aliases for <>(*args).
> 
>   -- Nikodemus
> 
> 
-- 
Dr. Nathaniel Pryce, Technical Director, B13media Ltd.
Studio 3a, 22-24 Highbury Grove, London N5 2EA, UK
http://www.b13media.com