foreach (x; a .. b) and foreach_reverse (x; a .. b) should be disallowed for floats

Steven Schveighoffer schveiguy at
Mon May 18 06:46:15 PDT 2009

On Sun, 17 May 2009 20:28:24 -0400, Andrei Alexandrescu  
<SeeWebsiteForEmail at> wrote:

> Consider:
>      foreach (x; 1.0 .. 4.1) writeln(x);
>      foreach_reverse (x; 1.0 .. 4.1) writeln(x);
> This sucks. foreach with interval for floating-point types should be  
> disallowed.

foreach_reverse sucks in its own right, while you're looking for stuff to  
get rid of, I think it can be done better.

foreach(x; 4 .. 1 ) should do a reverse interval (and looks way more  
foreach(x; array.reverse) should iterate in reverse.

for classes, using a method called reverse should work fine:

foreach(x; myclass.reverse)

Having to implement opApplyReverse is rediculous, and having a keyword  
like foreach_reverse is rediculous.  Reverse isn't the only interesting  
iteration pattern, so why focus a whole keyword and syntax on that?


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