deprecate some cmp keyword in favor of key in factorizations

[chapoton]

as a step towards python3

let us try to get rid of cmp= in factorizations

[chapoton]

New commits:

​6406454

trac 21145 first tentative

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​3b72723

trac 21145 more work on deprecating cmp in factorisations

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​d23c60a

no change to ordered tree (moved to another ticket)

[git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

​24f0320

trac 21145 work on cmp in factorisations

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​d2531cf

trac #21145 fixing one failing doctest

[chapoton]

bot is green !

[aapitzsch]

Calls like self.__x.sort(cmp=_cmp) will crash in python 3. I suggest you use cmp_to_key() from ​functools: self.__x.sort(key=cmp_to_key(_cmp))

[tscrim]

LGTM.

@aapitzsch Those should go away by the time we switch to Python3 (hopefully we will be there before EOL for Python2).

[tscrim]

Actually, I now understand Andre's comment, we should change

-self.__x.sort(cmp=_cmp)
+self.__x.sort(key=cmp_to_key(_cmp))

in the deprecated code to be python2/3 compatible now (I interpreted it as a long-term, sorry!).

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​930414a

trac #21145 using cmp_to_key in deprecated code

[tscrim]

Thanks, and sorry I didn't understand it earlier.