Python 3 preparation: Change for removed members of types module

[Wilfried Luebbe]

Some members were removed from the types module in Python 3. Replace the deprecated members by their modern equivalents.

Changes according to lib2to3/fixes/fix_types.py:

  'BooleanType' : 'bool',
  'BufferType' : 'memoryview',
  'ClassType' : 'type',
  'ComplexType' : 'complex',
  'DictType': 'dict',
  'DictionaryType' : 'dict',
  'EllipsisType' : 'type(Ellipsis)',
  'FloatType': 'float',
  'IntType': 'int',
  'ListType': 'list',
  'LongType': 'int',
  'ObjectType' : 'object',
  'NoneType': 'type(None)',
  'NotImplementedType' : 'type(NotImplemented)',
  'SliceType' : 'slice',
  'StringType': 'bytes', # XXX ?
  'StringTypes' : 'str', # XXX ?
  'TupleType': 'tuple',
  'TypeType' : 'type',
  'UnicodeType': 'str',
  'XRangeType' : 'range',

This ticket is tracked as a dependency of meta-ticket ticket:15980.

[Wilfried Luebbe]

8 failed doctests in src/sage/misc/explain_pickle.py.

[Wilfried Luebbe]

The generated code leads to 8 doctest failures, all of them in src/sage/misc/explain_pickle.py.

For details see the attachment.

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New commits:

​f741ed2

changes generated by 2to3 tool (types) for Python 3

[Wilfried Luebbe]

There is a Python ticket ​2to3 doesn't convert 'types.InstanceType' to 'object'.

The recommendation seems to be

or add

try:
  from types import InstanceType
except ImportError:
  InstanceType = object

to the top of the module; this would then work for both 2.x and 3.x (assuming that replacing InstanceType with object is actually correct in the code in question).

[Wilfried Luebbe]

Status updated to allow "needs work" ...

[Wilfried Luebbe]

It needs work on the failing doctests.

The failing tests seem all to be concerned with old style classes. Python 3 has only new style classes.
Maybe there are no more old style classes in Sage - and those tests might be removed??

Is there somebody familiar with src/sage/misc/explain_pickle.py who can comment?

[R. Andrew Ohana]

There are plenty of old style classes in Sage. A lot of the codebase is ancient and has not received much attention in years. I don't know the module at all, so I can't really help here.

[Frédéric Chapoton]

I am temporarily putting this to needs review to see what are the errors now.

[git]

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

​50c9d97

trac #15994 changing doctests in explain_pickle

[Frédéric Chapoton]

If somebody with expertise in pickles could have a look, that would be great.

[Frédéric Chapoton]

Let us split the "more easy" part of that in #20962.

[Frédéric Chapoton]

There remains only a very annoying issue with pickle and old-style classes.

[Frédéric Chapoton]

some work on that in #21230

[Jeroen Demeyer]

I'm willing to have a look at the explain_pickle.py thing (but not right now).

[Frédéric Chapoton]

remains one XRangeType and several ClassType

[Frédéric Chapoton]

XRangeType is handled in #21867

[Frédéric Chapoton]

one instance of ClassType? is handled in #22918

there remains only the 2 ClassType? in explain_pickle.

[Jeroen Demeyer]

This one was actually easy: you just need to pretend that isinstance(foo, types.ClassType) is always False on Python 3.

Note that I also did some cleanup, including adding an unrelated doctest. I hope that is acceptable.

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New commits:

​925b5a5

Do not require types.ClassType

[Frédéric Chapoton]

ok,let it be. Thanks