[issue17810] Implement PEP 3154 (pickle protocol 4)

[Alexandre Vassalotti]

Alexandre Vassalotti added the comment:

Stefan, I took a quick look at your patch. There is a couple things that stands out.

First, I think the implementation of BINGLOBAL and BINGLOBAL_BIG should be moved to another patch. Adding a binary version opcode for GLOBAL is a separate feature and it should be reviewed independently. Personally, I prefer the STACK_GLOBAL opcode I proposed as it much simpler to implement, but I am biased.

Next, the patch's formatting should be fixed to conform to PEP 7 and PEP 8. Make sure the formatting is consistent with the surrounding code. In particular, comments should be full sentences that explains why we need this code. Avoid adding comments that merely say what the code does, unless the code is complex.

In addition, please replace the uses of PyUnicode_InternFromString with the _Py_IDENTIFIER as needed. The latter allow the static strings to be garbage collected when the module is deleted, which is friendlier to embedded interpreters. It is also lead to cleaner code.

Finally, the class method check hack looks like a bug to me. There are multiple solutions here. For example, we could fix class methods to be cached so they always have the same ID once they are created. Or, we could remove the 'is' check completely if it is unnecessary.

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<http://bugs.python.org/issue17810>
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