On Saturday, 28 December 2013 at 17:23:38 UTC, Ola Fosheim
Grøstad wrote:
What you want is a (mild) warning if you use a templated
algorithm and that algorithm use a O(N) primitive where it is
invisible to the library user. A warning you should be able to
suppress (basically telling the compiler "trust me, this is
deliberate").
How is that significantly different than the current situation?
If you use walkLength, then that's you telling the compiler
"trust me, this is deliberate". The only difference is that the
current behavior doesn't use a warning, it just errors out with
"this thing doesn't define a length", which is reasonable
behavior.
FYI, if your thing defines length, then walkLength calls it. So
it's effectively as fast to use when your thing has length
defined, otherwise it suggests that you understand that a relaxed
constraint of O(N) is acceptable and will do that for you if
length doesn't exist.
