From: Daniel Brockman <daniel@...>
Date: 2005-07-15T10:44:07+09:00
Subject: Re: Difference between Class.new and class

"Robert Klemme" <bob.news@gmx.net> writes:

> There is no equivalent (yet) for "def foo(&b) b.call(1) end" with
> define_method, because you cannot do define_method(:foo) {|&b|
> b.call(1)}.

As Florian Frank pointed out, this is fixed in Ruby 1.9.

> Also, you cannot have default values for method arguments
> with [define_method].

I just wanted to point out that this is not a show-stopping problem.
In Ruby 1.9, `define_method' can do everything `def' can.

   def foo(bar, baz = QUUX, *rest)
     ...
   end

can be written as

   define_method :foo do |bar, *rest|
     baz = rest.empty? and QUUX or rest.shift
     ...
   end

For longer parameter lists, you could refactor a bit:

   class Array
     def shift_or default
       if empty? then default else shift end
     end
   end

   define_method :foo do |bar, *rest|
     baz1 = rest.shift_or QUUX1
     baz2 = rest.shift_or QUUX2
     baz3 = rest.shift_or QUUX3
     ...
   end

But of course, you already know this.

As I said, I just wanted to point out that `def' and `define_method'
are essentially equal in power as of Ruby 1.9.

-- 
Daniel Brockman <daniel@brockman.se>

    So really, we all have to ask ourselves:
    Am I waiting for RMS to do this?   --TTN.