Maybe we don't need foreach ;-)

[Lionello Lunesu]

Frits van Bommel wrote:
> Lionello Lunesu wrote:
>> I got so used to foreach in D, I've just ported it to C ;)
>>
>> namespace D {
>> template <typename T, int S>
>> inline size_t length( T (&a)[S] ) { return S; }
>> // Add overloads for your own containers
>> }
>>
>> #define foreach(ELEMENT,ARRAY) \
>>   for(size_t __L=D::length(ARRAY),__B=0,__I=0; !__B && __I<__L; 
>> assert(__L==D::length(ARRAY)), ++__I ) \
>>     if (__B = 1) \
>>       for(ELEMENT = ARRAY[__I]; __B; __B=0) // a break must make the 
>> main loop stop
> 
> I think you have a dangling-else bug here:
> 
>     if (whatever)
>         foreach(elt, arr) { something(); }
>     else
>         somethingelse();
> 
> What happens in this code? It looks like somethingelse() will be 
> executed if whatever evaluates to false, but IIRC the 'else' clause will 
> bind to the 'if' you have in your macro. Since that one never evaluates 
> to false, somethingelse() will never be called here.
> 
> I haven't tried it though, this was just from looking at it.
> Also, this won't manifest itself if you always use braces after 'if's so 
> this may be hard to spot the one time you forget :).

Good one, easily solvable though, by inverting __B and using "if () {} 
else for...".. Thanks!

L.