From: Luke Burton <redmine@...>
Date: 2009-02-11T06:11:21+09:00
Subject: [ruby-core:21967] [Bug #1141] assignment of variable in "right" if statement fails

Bug #1141: assignment of variable in "right" if statement fails
http://redmine.ruby-lang.org/issues/show/1141

Author: Luke Burton
Status: Open, Priority: Normal
ruby -v: ruby 1.8.6 (2008-08-11 patchlevel 287) [universal-darwin10.0] 

In Ruby 1.8

>> p(x) if x=42
(irb):1: warning: found = in conditional, should be ==
NameError: undefined local variable or method `x' for main:Object
from (irb):1

In Ruby 1.9

$ irb19
irb(main):001:0> p (x) if (x=42)
NameError: undefined local variable or method `x' for main:Object
from (irb):1
from /usr/local/bin/irb19:12:in `<main>'

However, if you move the if statement to the line before, naturally everything works.

Should variable assignment in "right" if clauses be permitted? I think so, since it allows you to be fairly concise and not have to do:

if x = 42
  p(x)
end

"Right" if clauses are permitted because they read naturally, I assume. I'm not sure whether people regard variable assignment in this case as reading very "naturally", but there is at the very least a lack of consistency between this type of if clause, and the more regular type of if clause.


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