From: George Ogata <g_ogata@...>
Date: 2002-11-24T18:41:19+09:00
Subject: Re: find arguments... is this possible

Michael Hale wrote:

> I noticed that many times I just hang on to the constuctor variables and
> use them later.  This code allows me to do that automatically.
> 
> class MyClass
> def initialize(first, second)
> local_variables.each { |each| eval("@#{each} = #{each}")
> }
> end
> 
> def a_method
> p instance_variables.collect { |each| eval("#{each}") }
> end
> end
> 
> MyClass.new('val1','val2').a_method
> 
> Produces:
> ["val1", "val2"]

How about something like:

class Class
  def init_simple(*syms)
    strs = syms.map {|s| s.id2name}
    self.module_eval %{def initialize #{strs.join(',')}; #{strs.map {|s| 
"@#{s} = #{s};"}.join} end}
  end
end

Then you just use this to create constructors:

class C
  self.init_simple :a, :b, :c

  def sum
    @a + @b + @c
  end
end

C.new(1, 2, 3).sum  # 6

Alternatively, you can piggyback a Struct:

C = Struct.new('C', :a, :b, :c)
class C
  def sum
    a + b + c
  end
end

C.new(1, 2, 3).sum  # 6