Clean up some _element_constructor_() methods

[pjbruin]

The coercion framework never calls _element_constructor_() methods without optional or keyword arguments on an input that is already in the correct parent. This ticket removes some unnecessary checks for this case.

I checked that (the branches of) the if statements removed by this ticket are never called by temporarily inserting assert statements. In some other cases, I added doctests showing that the respective if statements cannot be removed (because the _element_constructor_() method has a optional or keyword arguments).

The deleted code in multi_polynomial_libsingular is no longer needed because these cases are handled by coercion maps from/via the base ring since #29247.

CC: @tscrim

Component: coercion

Author: Peter Bruin

Branch/Commit: b526945

Reviewer: Frédéric Chapoton, Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/29375

[pjbruin]

Commit: 586f977

[pjbruin]

Branch: u/pbruin/29375-clean_up_element_constructor

[fchapoton]

comment:2

would you please fix the pyflakes warning from patchbot report ?

[sagetrac-git]

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

b526945

Trac 29375: remove unused imports

[sagetrac-git]

Changed commit from 586f977 to b526945

[pjbruin]

comment:4

Replying to @fchapoton:

would you please fix the pyflakes warning from patchbot report ?

Done, thanks.

[fchapoton]

comment:5

looks good to me, and the bot is fully green.

Maybe Travis, who knows better the coercion framework, could give his word ?

[tscrim]

comment:6

Replying to @fchapoton:

Maybe Travis, who knows better the coercion framework, could give his word ?

Yes, what is in the ticket description is correct (it is faster to do it there because it is Cython too). So +1 for doing this.

[fchapoton]

comment:7

ok, then let it be.

[fchapoton]

Reviewer: Frédéric Chapoton, Travis Scrimshaw

[vbraun]

Changed branch from u/pbruin/29375-clean_up_element_constructor to b526945