From: Chris Irish <chris.irish@...>
Date: 2005-12-03T06:05:45+09:00
Subject: Re: Make a symbol represent a method?

Jacob Fugal wrote:

>On 12/2/05, Chris Irish <chris.irish@libertydistribution.com> wrote:
>  
>
>>K.... I get it
>>One more thing, Can I use the symbol to call a method and pass arguments
>>to it?  Or is it just a reference to the methods name so that's not
>>possible?
>>    
>>
>
>Sure thing. The symbol is not a reference to the method at all. What
>the symbol is is a *key* into the objects method table, the value
>corresponding to that key is the reference to the Method object. I can
>use a symbol (it'll "auto-vivify", for lack of a better word) even
>without a corresponding method.
>
>As far as syntax for calling a method just using it's named symbol,
>there are two ways you can do this. The first is to use send:
>
>  class Greeter
>    def hello( name )
>      puts "Hello, #{name}!"
>    end
>  end
>
>  greeter = Greeter.new
>  greeter.send( :hello, "World" )
>  # prints "Hello, World!"
>
>An alternate technique is to grab an actual reference to the method
>itself. This is available using the 'method' method:
>
>  greeter = Greeter.new
>  meth = greeter.method( :hello )
>  meth.call( "World" )
>  # same output
>
>This latter approach allows you to perform the name lookup only once,
>even if you need to call the method several times. It's also useful
>when metaprogramming; you can grab a reference to an existing method
>before redefining it, then call the original method from inside the
>redefined method. Nifty!
>
>Jacob Fugal
>
>  
>
Thank's everyone :)