[#44036] [ruby-trunk - Feature #6242][Open] Ruby should support lists — "shugo (Shugo Maeda)" <redmine@...>

20 messages 2012/04/01

[#44084] [ruby-trunk - Bug #6246][Open] 1.9.3-p125 intermittent segfault — "jshow (Jodi Showers)" <jodi@...>

22 messages 2012/04/02

[#44156] [ruby-trunk - Feature #6265][Open] Remove 'useless' 'concatenation' syntax — "rosenfeld (Rodrigo Rosenfeld Rosas)" <rr.rosas@...>

45 messages 2012/04/06

[#44163] [ruby-trunk - Bug #6266][Open] encoding related exception with recent integrated psych — "jonforums (Jon Forums)" <redmine@...>

10 messages 2012/04/06

[#44303] [ruby-trunk - Feature #6284][Open] Add composition for procs — "pabloh (Pablo Herrero)" <pablodherrero@...>

57 messages 2012/04/12

[#44349] [ruby-trunk - Feature #6293][Open] new queue / blocking queues — "tenderlovemaking (Aaron Patterson)" <aaron@...>

10 messages 2012/04/13

[#44402] [ruby-trunk - Feature #6308][Open] Eliminate delegation from WeakRef — "headius (Charles Nutter)" <headius@...>

20 messages 2012/04/17

[#44403] [ruby-trunk - Feature #6309][Open] Add a reference queue for weak references — "headius (Charles Nutter)" <headius@...>

15 messages 2012/04/17

[#44533] [ruby-trunk - Bug #6341][Open] SIGSEGV: Thread.new { fork { GC.start } }.join — "rudolf (r stu3)" <redmine@...>

24 messages 2012/04/22

[#44630] [ruby-trunk - Feature #6361][Open] Bitwise string operations — "MartinBosslet (Martin Bosslet)" <Martin.Bosslet@...>

31 messages 2012/04/26

[#44648] [ruby-trunk - Feature #6367][Open] #same? for Enumerable — "prijutme4ty (Ilya Vorontsov)" <prijutme4ty@...>

16 messages 2012/04/26

[#44704] [ruby-trunk - Feature #6373][Open] public #self — "trans (Thomas Sawyer)" <transfire@...>

61 messages 2012/04/27

[#44748] [ruby-trunk - Feature #6376][Open] Feature lookup and checking if feature is loaded — "trans (Thomas Sawyer)" <transfire@...>

13 messages 2012/04/28

[ruby-core:44315] [ruby-trunk - Feature #6225] Hash#+

From: "alexeymuranov (Alexey Muranov)" <redmine@...>
Date: 2012-04-12 19:00:34 UTC
List: ruby-core #44315
Issue #6225 has been updated by alexeymuranov (Alexey Muranov).


Martin, it is common to use * for both commutative and non-commutative operations but + for only commutative.

But i am more in favor of Matz's argument, because i didn't bother myself about the fact that string addition is non -commutative.

duerst (Martin D端rst) wrote:
> In common sense, * is also commutative. But of course, for matrix multiplication, it's not.
> 
> Also, + is used in many fields of mathematics. I'm not a mathematician, but I very strongly doubt that it's commutative in all these cases. (see e.g. http://arxiv.org/abs/1003.2081 for an example)
> 
> What's much more important is whether the + for Hash fits the general image a Ruby programmer has for +. I'm not exactly sure about this, but the parallel with Array is not too bad.


----------------------------------------
Feature #6225: Hash#+
https://bugs.ruby-lang.org/issues/6225#change-25861

Author: trans (Thomas Sawyer)
Status: Assigned
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: core
Target version: 2.0.0


Strings and Arrays can be combined with #+. I don't see any reason not to allow Hashes to do so as well.

  class Hash
    alias :+ :merge
  end



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