Proposal: takeFront and takeBack

[Christophe Travert]

takeFront implementation is dangerous for ranges which invalidates their 
front value when popFront is called, for instance, File.byLine. Thus 
takeFront will have to be used with care: any range implement takeFront 
(because of the template and USFC), but it may not be valid. That makes 
the range interface more complicated: There is a takeFront property, but 
you have to check it is safe to use... how do you check that by the way?

Are there so many ranges that duplicate efforts in front and popFront, 
where there is no easy workarround? Would it be such an improvement in 
performance to add takeFront? strings being immutable, my guess would be 
that it is not that hard for the compiler to optimize a foreach loop (it 
should be easy to profile this...). Even if there is an efficiency 
issue, you could easily solve it by implementing a range wrapper or an 
opApply method to make foreach faster.

-- 
Christophe