From: dblack@...
Date: 2007-09-07T04:57:52+09:00
Subject: Re: Is this a bug or a feature?

Hi --

On Fri, 7 Sep 2007, Mark Volkmann wrote:

>
> On Sep 6, 2007, at 2:16 PM, Wilson Bilkovich wrote:
>
>> On 9/6/07, Martin Jansson <martialis@bigfoot.com> wrote:
>>> irb(main):002:0> i=1
>>> => 1
>>> irb(main):003:0> until (i+=1)>5
>>> irb(main):004:1> p i
>>> irb(main):005:1> end
>>> 2
>>> 3
>>> 4
>>> 5
>>> => nil
>>> irb(main):006:0> RUBY_VERSION
>>> => "1.8.3"
>>> 
>>> The condition is evaluated before the first iteration.
>>> 
>>> At least it's consistent:
>>> 
>>> irb(main):005:0> i = 1
>>> => 1
>>> irb(main):006:0> p i until (i+=1)>5
>>> 2
>>> 3
>>> 4
>>> 5
>>> => nil
>>> 
>>> I think it makes "until" less useful. Why would anyone want this?
>> 
>> What other behavior would you want, and why?
>> Here are some specs for the current behavior of 'until'. They may help.
>> http://rubyurl.com/12y
>
> I think what Martin wants is a bottom-tested loop, but I don't believe 
> Ruby has that. until is a top-tested loop just like while. The only way I 
> know to get bottom-tested behavior is this.
>
> loop do
> # some code goes here
> break if condition
> end

You can do:

  begin
    # do stuff
  end until condition


David

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