Difference between index and find_index

Rafa_F · February 26, 2016, 11:35am

Is there a difference between Array#index and Array#find_index? I can’t
see one from reading the docs, but the docs also do NOT say that one
method is just an alias to the other one, so there should be a
difference.

Ronald

ronaldfischer · February 27, 2016, 12:59pm

The docs aren’t perfect.

When we take alook a the ruby C-source, the comments above the function
rb_ary_index strongly suggest that #index and #find_index are the same.

github.com

ruby/ruby/blob/4df168074c9e80822b4326a4539600ae7dbe0adb/array.c

/**********************************************************************

  array.c -

  $Author$
  created at: Fri Aug  6 09:46:12 JST 1993

  Copyright (C) 1993-2007 Yukihiro Matsumoto
  Copyright (C) 2000  Network Applied Communication Laboratory, Inc.
  Copyright (C) 2000  Information-technology Promotion Agency, Japan

**********************************************************************/

#include "internal.h"
#include "ruby/util.h"
#include "ruby/st.h"
#include "probes.h"
#include "id.h"

#ifndef ARRAY_DEBUG

This file has been truncated. show original

To confirm this, we ask ruby itself:

a = Array.instance_method :index
b = Array.instance_method :find_index
c = Array.instance_method :rindex
puts a.eql? b # => true
puts a.eql? c # => false

See UnboundMethod#eql?