Re: Should (and can) the <algorithm> functions be extended by convenience helpers that take generic containers as parameters?
Martin B. wrote:
On 02.08.2011 05:30, Bo Persson wrote:
Martin B. wrote:
Many [algorithm
functions](http://www.cplusplus.com/reference/algorithm/) work
with a pair (or pairs) of iterators.
Often, these iterators will be used with container.begin() and
container.end().
Wouldn't it therefore make a lot of sense to have additional
helper functions that just take a generic container argument
instead of a pair of iterators?
Example:
...
Personally, I think this should just be part of the standard
library.
Barring this, does any such convenience header already exists,
that tries to add such helpers where they make sense?
There were proposals for this when the C++0x draft still contained
"concepts". In the general case, you would need the "concepts" to
decide what function to call. Otherwise there might be problems for
the compiler to decide among function like:
template<class RandomAccessContainer, class Compare>
void sort ( RandomAccessContainer cont, Compare comp );
template<class RandomAccessIterator>
void sort ( RandomAccessIterator first, RandomAccessIterator last);
Hmm ... I'd have thought this would be gracefully handled via
SFINAE?:
The container version would call `.begin()` and/or `.end()` on
`cont` and the iterator version would dereference `first` --
neither of which could compile for the other.
What am I missing?
That you are adding new requirements that just *might* break existing
code.
Right now I can sort a Matrix class that has both begin, end, and
operator* defined. How will the SFINAE find out which template to use?
I have seen ever more perverse examples where the container object
could have operator() defined and be used as its own comparer...
Bo Persson
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