Any chance to call Tango as Extended Standard Library

Steven Schveighoffer schveiguy at yahoo.com
Mon Jan 19 08:27:00 PST 2009


"Andrei Alexandrescu" wrote
> Steven Schveighoffer wrote:
>> While we're on the subject of ditching, can we get rid of 
>> foreach_reverse? How hard is it for a range to just have a reverse 
>> property:
>>
>> foreach(element; myrange.reverse)
>>
>> Which simply reverses the order of traversal?  That also would moot the 
>> toe/last/tail/etc. debate ;)
>
> I wish that debate went away. But eliminating toe and retreat would 
> require requiring .reverse as a primitive for *all* ranges, which is 
> wasteful and repetitive. Instead, a better design is to have ranges (those 
> that can) offer toe and retreat primitives such that a generic function 
> retro offers backward iteration for any range. In addition, certain 
> algorithms (such as the one that reverses a range in place) need to 
> manipulate the same range from two ends. Implementing them using .reverse 
> and a second range would be more difficult.

I didn't say you couldn't provide toe and retreat in Phobos' ranges (for the 
reverse-a-range function).  Most likely such an algorithm is not using 
foreach and foreach_reverse, but using the functions directly.

My point was, foreach_reverse is an eyesore and a hack, and there really is 
no need for it.  And what a perfect time to get rid of it, since we are 
already changing how foreach works ;)

I realize that this wouldn't really kill the toe debate for Phobos, but at 
least it would be a library decision, and not part of the compiler.

-Steve 





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