[Jaakko Jarvi]
for_each is the only one that takes a 'free-form' function object.
Yes, as I said, it is "special".
If side effects are allowed, I don't understand why for_each is classified as a non-modifying sequence. It sure can modify the elements of the sequence. What is (philosophically) different in the way that, say, std::replace, modifies the elements of the sequence?
Because for_each() does not do the modifying, the /functor/ does the modifying. Contrast replace(), which does the modifying itself.
Do you know what Bjarne is referring to with the 'recent standards resolution'?
I have E-mailed him asking for a clarification.
The sgi STL documentation (predecessor of what is currently in the standard)
... is wrong wrt the final Standard.
This must be the initial reason why for_each is in the category of non-modifying sequences.
It may have been that this was the intent pre-Standardization.
A DR would be in place: either explicitly mention that side-effects (of the sort that modify the values in the sequence) are not allowed, or move for_each to mutating algs. Volunteer to raise that and provide wording?
I don't believe that a DR is necessary given the phrasing in TC++PL, which is reasonably authoritative (though lacking Standard force). Stephan T. Lavavej