Isn't using find with retro awkward?

[Steven Schveighoffer]

On Wed, 16 Feb 2011 11:14:27 -0500, Andrej Mitrovic  
<andrej.mitrovich at gmail.com> wrote:

> On 2/16/11, spir <denis.spir at gmail.com> wrote:
>>
>> for any reason, I would prefere
>>      findBack(haystack, needle);
>> :-)
>
> Or maybe find should have an extra parameter that decides if the
> search begins from the beginning or the end of the range.

I just realized, this isn't possible in the general case.  That is, given  
your original range [5, 1, 2, 3, 4, 5, 1], the only way to get [5, 1] is  
to use popFront.

Think about this.  What are the basic operations of a bidirectional  
range?  popFront and popBack.  There is no way to search from the back,  
and then use that as the front end of the resulting range.

Essentially, the range API does not allow what you want unless you have a  
random-access range, and I don't even know if that can be generalized.   
The operation you are looking for is very different from what find does.

-Steve