From: Matthew Smillie <M.B.Smillie@...>
Date: 2006-06-11T03:57:35+09:00
Subject: Re: Global not evaluated properly in 'if' statement modifier

On Jun 10, 2006, at 19:13, darren kirby wrote:

> Hello all,
>
> I am scratching my head over this one.
> I have a method:
>
> def dispatchFile(file)
>   song = Convert.new(file)
>   case type
>   when 'ogg'
>     song.oggToWav
>     song.wavToOgg  if $outtype == 'ogg'
>     song.wavToMp3  if $outtype == 'mp3'
>     song.wavToM4b  if $outtype == 'm4b'
>     song.wavToFlac if $outtype == 'flac'
>   when 'mp3'
> <etc....>
>   end
> end
>
> When I run this code the 'if's are never evaluated. That is, I have  
> printed
> $outtype, and it has a valid value, but the second method which  
> matches the
> value never runs. If I comment out the 'if' and run the two methods  
> manually
> it works fine.
>
> In my tests $outtype's value is 'mp3', so why doesn't song.wavToMp3  
> run?
> What am I missing?

I'm not able to generalise this result, my similar code (at bottom)  
works as it should.

So, at a guess, I'd suggest that $outtype is not actually "mp3" but  
is "mp3\n".  #puts is smart enough not to include an extra \n, and if  
you're using #print, then the extra line break may not be obvious,  
since it would look just like the result of #puts.  Similarly, "mp3 "  
wouldn't display as obviously wrong.

For example:

irb(main):020:0> foo = "mp3\n"
irb(main):021:0> puts foo.inspect
"mp3\n"
=> nil
irb(main):022:0> puts foo
mp3
=> nil
irb(main):023:0> foo == 'mp3'
=> false

If that's not the case, then I'm stumped.

matthew smillie.


[this code works]

def foobar
   type = 'ogg'
   case type
   when 'ogg'
     puts "*always"
     puts "*ogg" if $outtype == 'ogg'
     puts "*mp3" if $outtype == 'mp3'
   end
end
=> nil
foobar
*always
*mp3
=> nil