"Peter Dimov" <pdimov@mmltd.net> wrote in message news:004101c41369$2ca8cb90$1d00a8c0@pdimov2...
Jonathan Turkanis wrote:
However, if you accept that comparisons criteria are alway
contextual,
I think you must conclude that the comparison operators <, <=, etc. are completely useless. On the contrary, I like the ability to have a default comparison criteria that works a good deal of the time;
Agree.
as long as it's provided, it should be customizable.
Disagree. Your own logic doesn't support this conclusion: a default comparison works most of the time, therefore, it doesn't need to be customizable, because you could only customize it to _not work_ most of the time.
Here's what I had in mind: for a particular application you might find that 'most of the time' you need a non-standard comparison criterion. It might make sense to let it be the default, so you can use the much cleaner operator notation.
And for the string case, the downside to encoding a comparison in the type is that you'll now spend a lot of time converting strings (because most libraries - correctly - accept an ordinary std::string, regardless of what comparisons they might make underneath, or they'd expose implementation details in the interface.)
You can expose the string as a typedef, to avoid bothering library users with custom comparison policies. Most of the interoperability concerns could be addressed by relaxing the requirement that traits_type match extacly in basic_string member functions which take basic_strings as arguments -- at least for those which don't involve comparison.
Nobody uses anything but std::string and std::wstring. ;-)
I've been waiting to meet the 'japan_char' I've read so much about; still haven't seen it. ;-) Jonathan