From: "boris_stitnicky (Boris Stitnicky)" <boris@...>
Date: 2013-04-18T13:26:02+09:00
Subject: [ruby-core:54423] [ruby-trunk - Feature #8237] Logical method chaining via inferred receiver


Issue #8237 has been updated by boris_stitnicky (Boris Stitnicky).


Wow, inferred reciever, that sounds cool. But wait, in Ruby we actually have
inferred receiver - it's self! When you frequently do

fred.say_this || fred.say_that && fred.compute_this || fred.compute_that

then the code wordiness is telling you that maybe you should teach fred

fred.compute_it_all_at_once

But I'm all for suggestions :-) How about if we finally allow Japanese
grammar into Ruby along English, and introduce global methods #��� for
temporary change in self (as headius hinted), #��� obj for replacing self
temporarily by [*self, obj], and ��� for resseting self back to this
object? We all need to learn typing Unicode efficiently nowadays and
using kana characters would save space and prevent confusion with other
things characters woul also save space...
----------------------------------------
Feature #8237: Logical method chaining via inferred receiver
https://bugs.ruby-lang.org/issues/8237#change-38689

Author: wardrop (Tom Wardrop)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 


=begin
This is a feature suggestion that was raised while discussing issue #8191. The feature suggestion is to introduce some form of logical method chaining to address this reasonably common pattern:

    user && user.profile && user.profile.website && user.profile.website.thumbnail

It would be reasonably trivial to shorten this to:

    user && .profile && .website && .thumbnail

The implementation I propose would be for Ruby to allow an inferred receiver; the dot prefix would be the syntax for this. The inferred receiver would resolve to the result of the last expression in the current scope. For illustrative purposes, the following would work under this proposal:

    "some string"
    puts .upcase #=> SOME STRING

Another example:

    puts .upcase if obj.success_message || obj.error_message

    # Instead of...

    message = (obj.success_message || obj.error_message)
    puts message.upcase if message

This can also potentially provide an alternative option in syntactically awkward scenario's, such as dealing with the return value of an if statement or a catch block, avoiding the need for temporary variable assignment:

    catch :halt do
      # Do something
    end

    if .nil?
       log.info "Request was halted" 
       response.body = "Sorry, but your request could not be completed"
    end

The logical chaining scenario is the main use case however. I just wanted to demonstrate how the proposed implementation could also be used in other creative ways.

=end


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