Clean up parent() and related functions

[jdemeyer]

1. Keep only inplace_threshold in coerce.pxi (that can be dealt with in another ticket) and move everything else to more appropriate places.
2. Define the global parent() function in structure/element.pyx and document it.
3. Move have_same_parent() to structure/element.pyx.
4. Remove superfluous parent() methods (where parent() is defined exactly as in the base Element class, so by inheritance it's not needed).

[jdemeyer]

New commits:

​18b968d	trac #10962: make Set_PythonType pickable
​97f3984	trac #10962: fix documentation
​da81792	trac #10962: fix unpickle (Sequences is not a parent)
​4b5c373	Remove useless C/API calls; improve error message
​f28f02a	Define parent() to be type() for SageObject
​29ce9a1	Clean up coerce.pxi

[ncohen]

(being curious)

[vdelecroix]

Hello Jeroen,

1) Why moving "parent_c" and "have_same_parent_c"?

2) Instead of

cdef inline parent_c(x):
    if isinstance(x, Element):
        return (<Element>x)._parent
    elif hasattr(x, 'parent'):
        return x.parent()
    else:
        return type(x)

wouldn't it be faster to do

cdef inline parent_c(x):
    if isinstance(x, Element):
        return (<Element>x)._parent
    else:
        try:
            return x.parent()
        except AttributeError:
            return type(x)

3) In element.pyx, the "seealso" should be a "SEEALSO".

Vincent

[jdemeyer]

Replying to vdelecroix:

Hello Jeroen,

1) Why moving "parent_c" and "have_same_parent_c"?

Mainly to get rid of coerce.pxi.

[git]

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

​a6eebf8

Minor fixes to parent()

[vdelecroix]

I just removed trailing whitespaces that you introduce. Beyond that, everything looks fine.

Vincent

---

New commits:

​977b597

remove trailing whitespaces

[jdemeyer]

Avoid a merge conflict with #17654.

---

New commits:

​2303c2e

Move lazy import to avoid merge conflict

[vdelecroix]

As you set dependencies in this order, I move back this one in needs review.

[jdemeyer]

Replying to vdelecroix:

As you set dependencies in this order

I didn't change any dependencies, I just added this one commit to avoid a conflict. You just have to review this last commit by itself.

[vdelecroix]

Replying to jdemeyer:

Replying to vdelecroix:

As you set dependencies in this order

I didn't change any dependencies, I just added this one commit to avoid a conflict. You just have to review this last commit by itself.

Ho, I see!

[vbraun]

Conflicts, probably with #10779

[git]

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

​c84246e	#10779: Improve coverage test for structure/element.pyx
​db023d4	Merge branch 'u/chapoton/10779' of ssh://trac.sagemath.org:22/sage into 10779
​2e30025	trac #10779 corrected 3 doctests
​9d72c81	Merge branch 'u/chapoton/10779' of ssh://trac.sagemath.org:22/sage into 10779
​9531937	trac #10779 correct failing doctest + more doc changes
​54396cd	Merge branch 'u/chapoton/10779' into 6.4
​dbf722e	Remove gcd, lcm, xgcd from element.pyx
​549795c	Merge ticket/10779 into ticket/17533

[git]

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

​730dc59

Merge tag '6.5.beta6' into ticket/17533