From: duerst@...
Date: 2014-12-18T06:12:32+00:00
Subject: [ruby-core:66937] [ruby-trunk - Bug #10450] multiple assignment in	conditional

Issue #10450 has been updated by Martin D��rst.


bug hit wrote:
> Yusuke Endoh wrote:
> > I think that the restriction is no longer meaningful, but it does not mean that this is a bug.  Whatever the reason is, the behavior has been the spec.  It is not harmful.  It is trivial to work around.  So I consider this ticket as a feature request.
> > 
> > I can reopen this ticket, but it has many noises and too long.  I also recommend you to open a new ticket to feature request tracker.

> If you can reopen, then please do, I think it's better not to have two tickets for the same issue.  I disagree that this is a feature.

It would be helpful if you could defer the triage into bugs and features to people such as Yusuke who have a lot of experience with how Ruby development works. Also, while it's better to not have two tickets for the same issue, it's better to have a new ticket because, as we had to find out, the current ticket mixes up two issues (allowing multiple assignment in conditions and removing parentheses), is confusing, and has accumulated a lot of dust.




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Bug #10450: multiple assignment in conditional
https://bugs.ruby-lang.org/issues/10450#change-50481

* Author: bug hit
* Status: Rejected
* Priority: Normal
* Assignee: 
* Category: 
* Target version: 
* ruby -v: ruby 2.1.4p265 (2014-10-27 revision 48166) [x86_64-linux]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
----------------------------------------
multiple assignment is an expression whose value can be truthy (array) or falsy (nil, false), so why is there a restriction on its use in conditionals?  A warning perhaps is justified, but a syntax error, why?


irb(main):001:0> if a, b = nil then 1 else 0 end
SyntaxError: (irb):1: syntax error, unexpected ',', expecting keyword_then or ';' or '\n'
if a, b = nil then 1 else 0 end
     ^
(irb):1: syntax error, unexpected keyword_then, expecting end-of-input
if a, b = nil then 1 else 0 end
                  ^
	from /home/alex/.rbenv/versions/2.1.4/bin/irb:11:in `<main>'
irb(main):002:0> if (a, b = nil) then 1 else 0 end
SyntaxError: (irb):2: multiple assignment in conditional
	from /home/alex/.rbenv/versions/2.1.4/bin/irb:11:in `<main>'
irb(main):003:0> (a, b = nil) ? 1 : 0
SyntaxError: (irb):3: multiple assignment in conditional
	from /home/alex/.rbenv/versions/2.1.4/bin/irb:11:in `<main>'
irb(main):004:0> (a, b = nil)
=> nil




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