From: "Marvin Gülker" <sutniuq@...>
Date: 2010-07-26T03:25:55+09:00
Subject: Re: * operator, Float

Иван Сташко wrote:
> Where is the * operator defined for Float?
> 
> ree-1.8.7-2010.02 > 3.0.methods.grep "*"
>  => ["*"]
> ree-1.8.7-2010.02 > 3.0.class
>  => Float
> ree-1.8.7-2010.02 > Float.methods.grep "*"
>  => []
> ree-1.8.7-2010.02 > Float.superclass
>  => Numeric
> ree-1.8.7-2010.02 > Numeric.methods.grep "*"
>  => []
> ree-1.8.7-2010.02 > Numeric.superclass
>  => Object
> ree-1.8.7-2010.02 > Object.methods.grep "*"
>  => []
> ree-1.8.7-2010.02 > Object.superclass
>  => nil
> 
> I'm guessing there's a mixin somewhere or this has to do with
> eigenclasses or perhaps a C-module has been mixed-in between Numeric and
> Float.  Where do I look at this code?

The way you're trying to find the #* method is wrong. You try to find 
Class#*, not Float#*. Try it this way:

irb(main):004:0> Float.public_instance_methods.map(&:to_s).grep("*")
=> ["*"]
irb(main):005:0> Numeric.public_instance_methods.map(&:to_s).grep("*")
=> []
irb(main):006:0>

If Float#* wasn't defined in C code, you could use 
Method#source_location to find out where it is defined (at least in Ruby 
1.9):

irb(main):006:0> 3.0.method(:*).source_location
=> nil
irb(main):007:0> require "pathname"
=> true
irb(main):008:0> Pathname.new("x").method(:to_s).source_location
=> ["/opt/rubies/ruby-1.9.1-p429/lib/ruby/1.9.1/pathname.rb", 248]
irb(main):009:0>

If #source_location gives you nil, you're dealing with a C method.

Marvin
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