From: Robert Klemme <shortcutter@...>
Date: 2009-12-01T03:50:06+09:00
Subject: Re: if statement modifier, with else, warning

On 30.11.2009 19:09, Gary Hasson wrote:
> The following statement works fine, even though it generates a warning.
> With regard to "if" and "unless" being used as statement modifiers, a
> manual states: "Obviously, this syntax does not allow any kind of else
> clause."
> 
>   compare_files unless @filename_1 == nil or @filename_2 == nil else
>     @messagetextctrl.append_text("  ==> Please specify files to compare.
> \n")
> 
> Error Msg: "...rb:112: warning: else without rescue is useless"
> 
> Obviously, the statement can be changed to the normal "if-else-end"
> format, but that would not be as Ruby-ish as the above approach.
> 
> Is there a good reason why Ruby should not allow "else" to be used as in
> the example above?

It's a syntax error because of the ambiguity:

robert@fussel ~
$ allruby -ce 'puts 1 if 2 > 0 else puts 3'
ruby 1.8.7 (2008-08-11 patchlevel 72) [i386-cygwin]
-e:1: syntax error, unexpected kELSE, expecting $end
puts 1 if 2 > 0 else puts 3
                     ^
ruby 1.9.1p243 (2009-07-16 revision 24175) [i386-cygwin]
-e:1: syntax error, unexpected keyword_else, expecting $end
puts 1 if 2 > 0 else puts 3
                     ^

Btw, I believe you might have another issue in your code because of the 
precedence of "or".  It might be safer to use "||" or proper bracketing.

Kind regards

	robert


-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/