From: Jamis Buck <jgb3@...>
Date: 2003-12-30T07:22:01+09:00
Subject: Re: Question about Ruby implementation

Dave Thomas wrote:

>
> It's good style in general. Consider
>
>   if (something)
>     MACRO;
>
> and
>
>   if (something)
>     MACRO;
>   else
>     puts("hello");
>
> With just {}'s around the macro, the second case wouldn't compile 
> (because of the semicolon).
>
>
> Cheers
>
>
> Dave
>
>

Yah, I understand that, I think.  But why have MACRO wrap its contents 
in a "do{...}while(0)", instead of just "{...}"?  In other words, is 
there a compelling reason to do this:

  #define MACRO(x) \
      do { \
        x \
      } while(0)

instead of this:

  #define MACRO(x) \
       { \
           x \
       }

I'm just curious -- if it just comes down to a personal preference 
thing, that's fine.  But if there is a good reason for doing one over 
the other, I'd like to know.  Thanks. :)

-- 
Jamis Buck
jgb3@email.byu.edu

ruby -h | ruby -e 'a=[];readlines.join.scan(/-(.)\[e|Kk(\S*)|le.l(..)e|#!(\S*)/) {|r| a << r.compact.first };puts "\n>#{a.join(%q/ /)}<\n\n"'