Transience of .front in input vs. forward ranges

[deadalnix]

Le 05/11/2012 08:58, Jonathan M Davis a écrit :
> On Sunday, November 04, 2012 21:07:46 H. S. Teoh wrote:
>> Stop right there. You're contradicting yourself. You kept saying that
>> transient ranges are rare, abnormal, etc., and now you say they are a
>> potentially large number of range types? I'm sorry, you've managed to
>> utterly confuse me.  Are they rare, or are they not?
>>
>> If they are rare, then this thin wrapper only needs to be written in
>> those few rare cases. *No other range type needs to be changed.*
>>
>> If they are common, then they aren't abnormal, and we should be fixing
>> Phobos to deal with them. Everywhere. In a pervasive, invasive, large
>> changeset, because almost all current code is broken w.r.t. to these
>> common cases -- if indeed they are common.
>
> Base ranges with transient fronts are rare, but as soon as you have to take
> them into account with wrapper ranges, then they potentially affect almost
> every range-based function in Phobos. So, you're taking a very rare case and
> forcing _everything_ to account for it. _That_ is why it affects a large number
> of range types.
>

Don't you understand that every other solution proposed here, including 
Andrei's, have the same very drawback ?

I'll add that this drawback is much worse, because with the ;transient 
solution, unmodified code will work correctly. With all other proposed 
behaviors, non updated code will expose undefined behavior when facing 
transient ranges, which is much worse.