From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-08-18T15:53:24+09:00
Subject: Re: Strange behavior of or condition in loop

On Wed, Aug 18, 2010 at 6:06 AM, John Sikora <john.sikora@xtera.com> wrote:
> AppleII717 wrote:
>> I don't understand why ruby's "or" acts differently in a loop.
>>
>> This is some code I pulled out of a rails model, expanded the
>> assignments and simulated in IRB (1.8.7 and 1.9.2rc)
>>
>> #simple boolean assignments
>> #Why does this work
>>
>>   dirty = false
>>   found = true
>>   dirty = dirty or found
>>   puts dirty.to_s  => true
>>
>
> A lot of great info in here but I was left with a question:
>
> Why did it work outside the loop (in the example given above) but not
> inside the loop? So I tried the inside the loop code both in irb and
> from a file (using 1.9.1) and I got false, not true. See the irb session
> below. It makes me feel better that it works the same way in both
> instances.
>
> AppleII717, are you sure you got 'true' in the code above? Note that
> there is a 'true' output, but I think that it is because (dirty = dirty)
> or found returns true, but dirty is false.
>
> irb(main):001:0> dirty = false
> => false
> irb(main):002:0> found = true
> => true
> irb(main):003:0> dirty = dirty or found
> => true
> irb(main):004:0> dirty
> => false
> irb(main):005:0> dirty.to_s
> => "false"
> irb(main):006:0>

~$ irb
irb(main):001:0> dirty = false
=> false
irb(main):002:0> found = true
=> true
irb(main):003:0> dirty = dirty or found
=> true
irb(main):004:0> dirty
=> false

This works as expected in Ruby 1.8.7.

Jesus.