Asp Forum - Re: Exploring Metaprogramming

Logan Capaldo

9/4/2006 3:24:00 AM

On Sep 3, 2006, at 10:39 PM, Michael Gorsuch wrote:

> I've got some downtime this weekend, so I'm pooring over various
> examples of
> metaprogramming w/ Ruby.
>
> I really like _why's example regarding Dwemthy, but am curious as
> to how to
> achieve my end.
>
> The article in question is here:
>
> http://poignantguide.net/ruby/chapter-6.htm...
>
> _why's method allows us to build 'traits' for the character (by
> calling the
> 'trait' class method), and the meta programming behind the scenes
> builds an
> 'initialize' instance method for the class.
>
> What if I want to build a second method called 'command'? It
> should place
> the argument in an array that can be referenced later. It will
> need to also
> build an initialize method for my class, but one of them will have
> to be
> overwritten.
>
> Does anyone have any smart ways to combine or chain these two
> initialize
> methods together?
>
> I ultimately want to do something like this:
>
> class Dragon < Creature
> traits :life
> life 100
>
> command :fly
>
> def fly
> puts "I am flying..."
> end
>
> end
>
> After an instance is created, it will contain the instance variable
> 'commands', which is an array holding the symbol 'fly'.
>

here's something to get you started:

class Creature
def self.command(com)
@commands ||= []
@commands |= [com]
end

def self.commands
@commands ||= []
end
end

class Dragon < Creature
command :fly
end

p Dragon.commands #=> [:fly]

> Does anyone have any ideas? In the end, I'd be adding more and
> more of
> these commands to my DSL. This is a DSL, right? ;-)

comp.lang.ruby

Re: Exploring Metaprogramming

Logan Capaldo

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