[ruby-core:47046] [ruby-trunk - Bug #6596] New method for Arrays : Array#index

Issue #6596 has been updated by trans (Thomas Sawyer).


Given a ordered list, swap items relative to those that match.

  list.index_all{ |x| match?(x) }.each do |i|
    list[i], list[i+1] = list[i+1], list[i]
  end

vs. what?

  list.each_with_index do |x, i|
    if match?(x)
      list[i], list[i+1] = list[i+1], list[i]
    end
  end

Nope, that doesn't work. Could clone `list` but that would be rather inefficient. Better idea? A built-in #index_all is going to be a lot faster then a Ruby code implementation of the same.


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Bug #6596: New method for Arrays : Array#index
https://bugs.ruby-lang.org/issues/6596#change-28701

Author: robin850 (Robin Dupret)
Status: Feedback
Priority: Normal
Assignee: 
Category: core
Target version: 2.0.0
ruby -v: 2.0.0


Hello

5 days ago, I submitted a pull request on Github which provides a new method for the array objects which is Array#indexes. I have fist edit the Array#index method in order it to return an array of indexes and not a single index (which is the first occurrence it finds). I found it more logical but a user (trans) tells us that it could break the contract of Array#index so I decided to move it into Array#indexes. Eric (drbrain) tells me I should reasonning why I want to add this method ; it's just a point of view : I don't really understand why Array#index return a single index if the parameter is in the array several times. 

Examples

a = [1, 2, 3, 1]
a.indexes(1)
Return : [0, 3]
a.index(1)
Return : 0
In my opinion, it's not really logical, 1 is in the array twice

Moreover, this pull request doesn't beak anything because we don't edit the Array#index method so programms which were created with previous version of Ruby will work. 

I hope my post is complete. Have a nice day.




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