From: dblack@...
Date: 2006-03-25T20:51:55+09:00
Subject: Re: meaning of *array

Hi --

On Sat, 25 Mar 2006, Benjohn Barnes wrote:

> That makes a lot of sense, thank you! Usually this will be used to allow a 
> function to take additional arguments:
>
> def a_function( required_argument, also_required, *any_optional_arguments )
> 	puts required_argument
> 	puts also_required
> 	puts any_optional_arguments.join(',')
> end
>
> Calling:
>> irb(main):006:0> a_function(1,2,3,4,5)
>> 1
>> 2
>> 3,4,5
>
> You can also use it to split out an array in to seperate parameters (so kind 
> of the opposite of the above). Again, this is often used when calling a 
> method:
>
>> irb(main):007:0> a=[1,2,3,4,5]
>> => [1, 2, 3, 4, 5]
>> irb(main):008:0> a_function(*a)
>> 1
>> 2
>> 3,4,5

The two uses seem opposite, in a sense, but they're actually the same,
if you think of the following equivalency:

   list,of,things  <=>  *array

In both cases, the star "translates" between an array and a list of
things.


David

-- 
David A. Black (dblack@wobblini.net)
Ruby Power and Light, LLC (http://www.rubypowerandlight.com)

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