[#66126] Creation/Conversion methods/functions table for Ruby types — SASADA Koichi <ko1@...>
Hi,
5 messages
2014/11/07
[#66248] [ruby-trunk - Feature #10423] [PATCH] opt_str_lit*: avoid literal string allocations — normalperson@...
Issue #10423 has been updated by Eric Wong.
3 messages
2014/11/13
[#66595] [ruby-trunk - Bug #10557] [Open] Block not given when the argument is a string — bartosz@...
Issue #10557 has been reported by Bartosz Kopinski.
3 messages
2014/11/30
[ruby-core:66067] [ruby-trunk - Bug #10450] multiple assignment in conditional
From:
jballanc@...
Date:
2014-11-03 10:11:02 UTC
List:
ruby-core #66067
Issue #10450 has been updated by Joshua Ballanco.
Yes, but consider:
~~~
if a = (b, c = false, false)
puts "a is #{a}, b is #{b}, c is #{c} and everything together is true"
end
~~~
So if you were hoping to use multiple assignment to check the `&&`-ed boolean values of the individual conditions (or even the `||`-ed value), then you would be rudely surprised. In fact:
~~~
def gimmie_nil
nil
end
if a = (b, c = gimmie_nil(), gimmie_nil())
puts "Still true..."
end
~~~
...there is no way that the conditional would ever evaluate to false!
----------------------------------------
Bug #10450: multiple assignment in conditional
https://bugs.ruby-lang.org/issues/10450#change-49785
* Author: bug hit
* Status: Open
* 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
--
https://bugs.ruby-lang.org/