[with patch, positive review] Add a standard constructor for dynamic classes

[nthiery]

This patch implements sage.structure.dynamic_class.dynamic_class, for constructing dynamically new python classes. The constructed classes can be pickled, and have unique representation.

The patch includes a discussion on the relevance of dynamic classes for Sage.

Depends on #5985 for pickling and #5120.

Used by the upcoming category framework #5891, (and sage-words?)

Issue: is sage.structure.dynamic_class.dynamic_class the natural location for this?

[nthiery]

Patch updated for new version of #5120 Please ignore dynamic_class-5991-submitted.2.patch

[roed]

Looks good. Doctests pass.

[ncalexan]

Since this depends on #5985 which does not have a positive review it will have to wait.

[boothby]

Doctest failures:

sage -t -long devel/sage/sage/structure/dynamic_class.py
**********************************************************************
File "/space/boothby/sage-4.0.3/devel/sage-main/sage/structure/dynamic_class.py", line 210:
    sage: loads(dumps(BarFoo))
Exception raised:
    Traceback (most recent call last):
      File "/space/boothby/sage-4.0.3/local/bin/ncadoctest.py", line 1231, in run_one_test
        self.run_one_example(test, example, filename, compileflags)
      File "/space/boothby/sage-4.0.3/local/bin/sagedoctest.py", line 38, in run_one_example
        OrigDocTestRunner.run_one_example(self, test, example, filename, compileflags)
      File "/space/boothby/sage-4.0.3/local/bin/ncadoctest.py", line 1172, in run_one_example
        compileflags, 1) in test.globs
      File "<doctest __main__.example_1[23]>", line 1, in <module>
        loads(dumps(BarFoo))###line 210:
    sage: loads(dumps(BarFoo))
      File "sage_object.pyx", line 604, in sage.structure.sage_object.dumps (sage/structure/sage_ob$
        return comp.compress(cPickle.dumps(obj, protocol=2))
    PicklingError: Can't pickle <class '__main__.BarFoo'>: attribute lookup __main__.BarFoo failed
**********************************************************************
File "/space/boothby/sage-4.0.3/devel/sage-main/sage/structure/dynamic_class.py", line 224:
    sage: import sage.misc.cPickle as cPickle
Exception raised:
    Traceback (most recent call last):
      File "/space/boothby/sage-4.0.3/local/bin/ncadoctest.py", line 1231, in run_one_test
        self.run_one_example(test, example, filename, compileflags)
      File "/space/boothby/sage-4.0.3/local/bin/sagedoctest.py", line 38, in run_one_example
        OrigDocTestRunner.run_one_example(self, test, example, filename, compileflags)
      File "/space/boothby/sage-4.0.3/local/bin/ncadoctest.py", line 1172, in run_one_example
        compileflags, 1) in test.globs
      File "<doctest __main__.example_1[30]>", line 1, in <module>
        import sage.misc.cPickle as cPickle###line 224:
    sage: import sage.misc.cPickle as cPickle
    ImportError: No module named cPickle
**********************************************************************
File "/space/boothby/sage-4.0.3/devel/sage-main/sage/structure/dynamic_class.py", line 225:
    sage: cPickle.loads(cPickle.dumps(FooBar)) == FooBar
Exception raised:
    Traceback (most recent call last):
      File "/space/boothby/sage-4.0.3/local/bin/ncadoctest.py", line 1231, in run_one_test
        self.run_one_example(test, example, filename, compileflags)
      File "/space/boothby/sage-4.0.3/local/bin/sagedoctest.py", line 38, in run_one_example
        OrigDocTestRunner.run_one_example(self, test, example, filename, compileflags)
      File "/space/boothby/sage-4.0.3/local/bin/ncadoctest.py", line 1172, in run_one_example
        compileflags, 1) in test.globs
      File "<doctest __main__.example_1[31]>", line 1, in <module>
        cPickle.loads(cPickle.dumps(FooBar)) == FooBar###line 225:
    sage: cPickle.loads(cPickle.dumps(FooBar)) == FooBar
    NameError: name 'cPickle' is not defined
**********************************************************************
File "/space/boothby/sage-4.0.3/devel/sage-main/sage/structure/dynamic_class.py", line 238:
    sage: loads(dumps(FooUnique)) is FooUnique
Exception raised:
    Traceback (most recent call last):
      File "/space/boothby/sage-4.0.3/local/bin/ncadoctest.py", line 1231, in run_one_test
        self.run_one_example(test, example, filename, compileflags)
      File "/space/boothby/sage-4.0.3/local/bin/sagedoctest.py", line 38, in run_one_example
        OrigDocTestRunner.run_one_example(self, test, example, filename, compileflags)
      File "/space/boothby/sage-4.0.3/local/bin/ncadoctest.py", line 1172, in run_one_example
        compileflags, 1) in test.globs
      File "<doctest __main__.example_1[35]>", line 1, in <module>
        loads(dumps(FooUnique)) is FooUnique###line 238:
    sage: loads(dumps(FooUnique)) is FooUnique
      File "sage_object.pyx", line 604, in sage.structure.sage_object.dumps (sage/structure/sage_ob$
        return comp.compress(cPickle.dumps(obj, protocol=2))
    PicklingError: Can't pickle <class '__main__.Foo'>: it's not the same object as __main__.Foo
**********************************************************************
1 items had failures:
   4 of  36 in __main__.example_1
***Test Failed*** 4 failures.

[nthiery]

Yeah: it depends on #5985, but otherwise is ready.

Should there be a new field in the trac server for listing systematically the other tickets the ticket depends on?

[nthiery]

The two added patches, by David and myself improve introspection. I give a positive review on David's. David, can you double check mine?

[nthiery]

Replying to nthiery:

The two added patches, by David and myself improve introspection. I give a positive review on David's. David, can you double check mine?

The updated referee patch by myself adds a copyright header, and fixes a warning in sage -docbuild.

David: please double check!

[nthiery]

Fix reduction after David's referee patch

[nthiery]

Fold of all the patches above. Apply only this one

[nthiery]

David: can you have a quick look at my latest addition, and set a positive review (pending #5985)

[roed]

So, I approve the changes. I don't have time right now to run doctests though: the release manager (or someone) should make sure to do so.

[nthiery]

Replying to roed:

So, I approve the changes. I don't have time right now to run doctests though: the release manager (or someone) should make sure to do so.

Thanks! All the doctest pass on my machine, but yes, a triple check would be good.

[nthiery]

If #5985 is ready on time to get integrated in 4.1.2, it would be great to have this on go in too.

[was]

NOTE to self -- the change to sageinspect needs to be ported into the separated notebook when this is merged.

[mhansen]

I had to make the change to the way cPickle is imported as in #5985. I'll make a new ticket for sageinspect in the separated notebook.