if(;){} opinion

[clayasaurus]

I'll vote against it because I don't understand the value of

if (m; search("abcdef", "BcdasdfD"))

over

if (Regexp m = search("abcdef", "BcdasdfD") ) .

Maybe someone can enlighten me?


Georg Wrede wrote:
> Better 'fess up front: the intent of this post is to once and for all 
> murder, pulverize and extradite the new if construct.
> 
> Consider:
> 
>         if (m; std.regexp.search("abcdef", "b(c)d"))
>         {
>             writefln("[%s]", m.pre);      // prints [a]
>             writefln("[%s]", m.post);     // prints [ef]
>             writefln("[%s]", m.match(0)); // prints [bcd]
>             writefln("[%s]", m.match(1)); // prints [c]
>             writefln("[%s]", m.match(2)); // prints []
>         }
> 
> Flauting this around has shown that experienced programmers have a hard 
> time figuring out what is going on here.
> 
> Consider:
> 
>         if (m; std.regexp.search("abcdef", "b(c)d"))
> 
> Most everybody take it for granted that here is a typo, the '(m;' must 
> be the result of a sloppy copy-paste.
> 
> And in the previous case the theories ranged from all kinds of 
> behind-the-scenes magic.
> 
> Now consider:
> 
>         if (Regexp m = std.regexp.search("abcdef", "b(c)d"))
>         {
>             writefln("[%s]", m.pre);      // prints [a]
>             writefln("[%s]", m.post);     // prints [ef]
>             writefln("[%s]", m.match(0)); // prints [bcd]
>             writefln("[%s]", m.match(1)); // prints [c]
>             writefln("[%s]", m.match(2)); // prints []
>         }
> 
> Flaunting this around (to both the original programmers, and also to 
> virgin victims), gave the same, _immediate_ comment from everybody: "Ah, 
> that's neat!"