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#27390 closed enhancement (fixed)

Py3: test_class_pickling.py fix method resolution order error

Reported by:	vklein	Owned by:
Priority:	major	Milestone:	sage-8.7
Component:	python3	Keywords:
Cc:		Merged in:
Authors:	Vincent Klein	Reviewers:	Jeroen Demeyer
Report Upstream:	N/A	Work issues:
Branch:	6946310 (Commits)	Commit:	6946310194a5407fa2e77a9241de5f51c3650b17
Dependencies:		Stopgaps:

Description (last modified by jdemeyer)

Fix the

sage -t --long src/sage/misc/test_class_pickling.py
**********************************************************************
File "src/sage/misc/test_class_pickling.py", line 20, in sage.misc.test_class_pickling.metaclass
Failed example:
    c = metaclass("foo2", (object, bar,))
Exception raised:
    Traceback (most recent call last):
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 671, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 1095, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.misc.test_class_pickling.metaclass[1]>", line 1, in <module>
        c = metaclass("foo2", (object, bar,))
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/misc/test_class_pickling.py", line 31, in metaclass
        result = Metaclass(name, bases, dict())
    TypeError: Cannot create a consistent method resolution
    order (MRO) for bases object, bar
**********************************************************************

errors in python3.

As bar inherit from object python3 is unable to define the method resolution order.

Add another test object and rewrite the doctests with this object.

This ticket fixes all python3 errors in test_class_pickling.py

Change History (16)

comment:1 Changed 7 months ago by vklein

Branch set to u/vklein/27390

comment:2 Changed 7 months ago by git

Commit set to 82f97c33db686d77a2dc0c8878151cafca380ce5

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

82f97c3 Trac #27390: Fix misc.test_class_pickling for py3

comment:3 Changed 7 months ago by vklein

Status changed from new to needs_review

comment:4 Changed 7 months ago by jdemeyer

Status changed from needs_review to needs_info

It would be useful if you could post the actual errors that this ticket is supposed to fix.

comment:5 Changed 7 months ago by vklein

Status changed from needs_info to needs_review

Sure :

sage -t --long src/sage/misc/test_class_pickling.py
too many failed tests, not using stored timings
Running doctests with ID 2019-03-01-15-36-28-4c28d334.
Git branch: develop
Using --optional=dochtml,gmpy2,memlimit,mpir,python2,sage
Doctesting 1 file.
sage -t --long src/sage/misc/test_class_pickling.py
**********************************************************************
File "src/sage/misc/test_class_pickling.py", line 20, in sage.misc.test_class_pickling.metaclass
Failed example:
    c = metaclass("foo2", (object, bar,))
Exception raised:
    Traceback (most recent call last):
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 671, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 1095, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.misc.test_class_pickling.metaclass[1]>", line 1, in <module>
        c = metaclass("foo2", (object, bar,))
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/misc/test_class_pickling.py", line 31, in metaclass
        result = Metaclass(name, bases, dict())
    TypeError: Cannot create a consistent method resolution
    order (MRO) for bases object, bar
**********************************************************************
File "src/sage/misc/test_class_pickling.py", line 22, in sage.misc.test_class_pickling.metaclass
Failed example:
    c
Exception raised:
    Traceback (most recent call last):
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 671, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 1095, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.misc.test_class_pickling.metaclass[2]>", line 1, in <module>
        c
    NameError: name 'c' is not defined
**********************************************************************
File "src/sage/misc/test_class_pickling.py", line 24, in sage.misc.test_class_pickling.metaclass
Failed example:
    type(c)
Exception raised:
    Traceback (most recent call last):
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 671, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 1095, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.misc.test_class_pickling.metaclass[3]>", line 1, in <module>
        type(c)
    NameError: name 'c' is not defined
**********************************************************************
File "src/sage/misc/test_class_pickling.py", line 26, in sage.misc.test_class_pickling.metaclass
Failed example:
    c.__bases__
Exception raised:
    Traceback (most recent call last):
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 671, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 1095, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.misc.test_class_pickling.metaclass[4]>", line 1, in <module>
        c.__bases__
    NameError: name 'c' is not defined
**********************************************************************
File "src/sage/misc/test_class_pickling.py", line 49, in sage.misc.test_class_pickling.Metaclass
Failed example:
    c = metaclass("foo", (object, bar,))
Exception raised:
    Traceback (most recent call last):
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 671, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 1095, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.misc.test_class_pickling.Metaclass[1]>", line 1, in <module>
        c = metaclass("foo", (object, bar,))
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/misc/test_class_pickling.py", line 31, in metaclass
        result = Metaclass(name, bases, dict())
    TypeError: Cannot create a consistent method resolution
    order (MRO) for bases object, bar
**********************************************************************
File "src/sage/misc/test_class_pickling.py", line 52, in sage.misc.test_class_pickling.Metaclass
Failed example:
    s = cPickle.dumps(c)
Exception raised:
    Traceback (most recent call last):
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 671, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 1095, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.misc.test_class_pickling.Metaclass[3]>", line 1, in <module>
        s = cPickle.dumps(c)
    NameError: name 'c' is not defined
**********************************************************************
File "src/sage/misc/test_class_pickling.py", line 54, in sage.misc.test_class_pickling.Metaclass
Failed example:
    c2 = cPickle.loads(s)
Exception raised:
    Traceback (most recent call last):
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 671, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 1095, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.misc.test_class_pickling.Metaclass[4]>", line 1, in <module>
        c2 = cPickle.loads(s)
    NameError: name 's' is not defined
**********************************************************************
File "src/sage/misc/test_class_pickling.py", line 56, in sage.misc.test_class_pickling.Metaclass
Failed example:
    c == c2
Exception raised:
    Traceback (most recent call last):
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 671, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 1095, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.misc.test_class_pickling.Metaclass[5]>", line 1, in <module>
        c == c2
    NameError: name 'c' is not defined
**********************************************************************
File "src/sage/misc/test_class_pickling.py", line 72, in sage.misc.test_class_pickling.Metaclass.__reduce__
Failed example:
    c = metaclass("foo3", (object, bar,))
Exception raised:
    Traceback (most recent call last):
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 671, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 1095, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.misc.test_class_pickling.Metaclass.__reduce__[1]>", line 1, in <module>
        c = metaclass("foo3", (object, bar,))
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/misc/test_class_pickling.py", line 31, in metaclass
        result = Metaclass(name, bases, dict())
    TypeError: Cannot create a consistent method resolution
    order (MRO) for bases object, bar
**********************************************************************
File "src/sage/misc/test_class_pickling.py", line 74, in sage.misc.test_class_pickling.Metaclass.__reduce__
Failed example:
    c.__class__.__reduce__(c)
Exception raised:
    Traceback (most recent call last):
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 671, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/vklein/odk/sage/local/lib/python3.6/site-packages/sage/doctest/forker.py", line 1095, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.misc.test_class_pickling.Metaclass.__reduce__[2]>", line 1, in <module>
        c.__class__.__reduce__(c)
    NameError: name 'c' is not defined
**********************************************************************
3 items had failures:
   4 of   7 in sage.misc.test_class_pickling.Metaclass
   2 of   4 in sage.misc.test_class_pickling.Metaclass.__reduce__
   4 of   6 in sage.misc.test_class_pickling.metaclass
    [14 tests, 10 failures, 0.01 s]
----------------------------------------------------------------------
sage -t --long src/sage/misc/test_class_pickling.py  # 10 doctests failed
----------------------------------------------------------------------
Total time for all tests: 0.0 seconds
    cpu time: 0.0 seconds
    cumulative wall time: 0.0 seconds

comment:6 Changed 7 months ago by jdemeyer

Description modified (diff)

I don't understand why adding the class alpha would fix anything.

comment:7 Changed 7 months ago by vklein

It's not really about adding a class alpha. The goal is just to have two classes with no inheritance relationship in order to do a successful call to the metaclass function.

Last edited 7 months ago by vklein (previous) (diff)

comment:8 Changed 7 months ago by jdemeyer

But why does it fail in Python 3 in the first place?

comment:9 follow-up: ↓ 10 Changed 7 months ago by vklein

For me the question is more why it works in python2:

py2

>>> class a:
...     pass
... 
>>> class b(object, a):
...     pass
... 
>>> class c(a,b):
...     pass
... 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: Error when calling the metaclass bases
    Cannot create a consistent method resolution
order (MRO) for bases a, b

py3

>>> class a:
...     pass
... 
>>> class b(object, a):
...     pass
... 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: Cannot create a consistent method resolution
order (MRO) for bases a, object

Python3 looks more consistent to me.

comment:10 in reply to: ↑ 9 Changed 7 months ago by jdemeyer

Yes of course, I was confusing MRO errors with metaclass errors because I saw the word metaclass in the code.

comment:11 Changed 7 months ago by jdemeyer

Status changed from needs_review to needs_work

Since this doctests isn't about MROs, I think that a better and simpler solution would be to change the bases (object, bar) to (bar, object).

comment:12 Changed 7 months ago by vklein

Ok i will do that.

comment:13 Changed 7 months ago by git

Commit changed from 82f97c33db686d77a2dc0c8878151cafca380ce5 to 6946310194a5407fa2e77a9241de5f51c3650b17

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

6946310 Trac #27390: Implement a simpler solution.

comment:14 Changed 7 months ago by vklein

Status changed from needs_work to needs_review

comment:15 Changed 7 months ago by jdemeyer

Reviewers set to Jeroen Demeyer
Status changed from needs_review to positive_review

comment:16 Changed 7 months ago by vbraun

Branch changed from u/vklein/27390 to 6946310194a5407fa2e77a9241de5f51c3650b17
Resolution set to fixed
Status changed from positive_review to closed

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