some notion of low-level efficiency. Undid that, but left one routine
alone: save_inst() claims it has a reason for not using memoize().
I don't understand that comment, so added an XXX comment there.
then the embedded argument consumes at least 256 bytes. The difference
between a 3-byte prefix (LONG2 + 2 bytes) and a 5-byte prefix (LONG4 +
4 bytes) is at worst less than 1%. Note that binary strings and binary
Unicode strings also have only "size is 1 byte, or size is 4 bytes?"
flavors, and I expect for the same reason. The only place a 2-byte
thingie was used was in BININT2, where the 2 bytes make up the *entire*
embedded argument (and now EXT2 also does this); that's a large savings
over 4 bytes, because the total opcode+argument size is so small in
the BININT2/EXT2 case.
Removed the TAKEN_FROM_ARGUMENT "number of bytes" code, and bifurcated it
into TAKEN_FROM_ARGUMENT1 and TAKEN_FROM_ARGUMENT4. Now there's enough
info in ArgumentDescriptor objects to deduce the # of bytes consumed by
each opcode.
Rearranged the order in which proto2 opcodes are listed in pickle.py.
add memoize() helper function to update the memo.
The first element of the tuple returned by __reduce__() must be a
callable. If it isn't the Unpickler will raise an error. Catch this
error in the pickler and raise the error there.
The memoize() helper also has a comment explaining how the memo
works. So methods can't use memoize() because the write funny codes.
This fixes the charming, but unhelpful error message for
>>> pickle.dumps(type.__new__)
Can't pickle <built-in method __new__ of type object at 0x812a440>: it's not the same object as datetime.math.__new__
Bugfix candidate.
Change pickling format for bools to use a backwards compatible
encoding. This means you can pickle True or False on Python 2.3
and Python 2.2 or before will read it back as 1 or 0. The code
used for pickling bools before would create pickles that could
not be read in previous Python versions.
PEP 285. Everything described in the PEP is here, and there is even
some documentation. I had to fix 12 unit tests; all but one of these
were printing Boolean outcomes that changed from 0/1 to False/True.
(The exception is test_unicode.py, which did a type(x) == type(y)
style comparison. I could've fixed that with a single line using
issubtype(x, type(y)), but instead chose to be explicit about those
places where a bool is expected.
Still to do: perhaps more documentation; change standard library
modules to return False/True from predicates.
metaclass, reported by Dan Parisien.
Objects that are instances of custom metaclasses, i.e. whose class is
a subclass of 'type', should be pickled the same as new-style classes
(objects whose class is 'type'). This can't be done through a
dispatch table entry, and the __reduce__ trick doesn't work for these,
since it finds the unbound __reduce__ for instances of the class
(inherited from 'object'). So check explicitly using issubclass().
load_inst(): Implement the security hook that cPickle already had.
When unpickling callables which are not classes, we look to see if the
object has an attribute __safe_for_unpickling__. If this exists and
has a true value, then we can call it to create the unpickled object.
Otherwise we raise an UnpicklingError.
find_class(): We no longer mask ImportError, KeyError, and
AttributeError by transforming them into SystemError. The latter is
definitely not the right thing to do, so we let the former three
exceptions simply propagate up if they occur, i.e. we remove the
try/except!
Tim Peters
Guido van Rossum
Jeremy Hylton
Martin v. Löwis
Raymond Hettinger
Neal Norwitz
Fred Drake
Barry Warsaw