From: "prijutme4ty (Ilya Vorontsov)" <prijutme4ty@...>
Date: 2013-05-26T20:41:58+09:00
Subject: [ruby-core:55166] [ruby-trunk - Feature #8452][Open] Kernel#otherwise to rewrite code like (obj || default_obj).do_smth


Issue #8452 has been reported by prijutme4ty (Ilya Vorontsov).

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Feature #8452: Kernel#otherwise to rewrite code like (obj || default_obj).do_smth
https://bugs.ruby-lang.org/issues/8452

Author: prijutme4ty (Ilya Vorontsov)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 


Imagine you have code like this 
    (long_computation_chain || []).do_smth
While it isn't difficult, but it forces a developer to use additional parentheses. It can be difficult to trace where opening bracket is when computation_chain is long. Due to this idiom code cannot be read or written left to right. This is the same problem as for 
    Hash[ *long_computation ]

So I propose a simple method Kernel#otherwise

    def otherwise(value, check = nil)
      if !check
        self || value
      else
        check.to_proc.call(self) ? self : value
      end
    end

So now one can write:
    long_computation_chain.otherwise([]).do_smth 
or
    long_computation_chain.otherwise('default', :empty?).do_smth
or
    long_computation_chain.otherwise('numbers not allowed', ->(x){ x.grep(/\d+/) }).do_smth



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