2013/11/6 R. David Murray <rdmur...@bitdance.com>: > On Wed, 06 Nov 2013 23:34:22 +1100, Steven D'Aprano <st...@pearwood.info> > wrote: >> On Tue, Nov 05, 2013 at 08:38:09PM -0800, Ethan Furman wrote: >> >> > http://bugs.python.org/issue19332 >> >> Duplicate of this: http://bugs.python.org/issue6017 >> >> The conclusion on that also was that it is not worth guarding against >> such an unusual circumstance. > > If I remember correctly (and I may not) the size-change guards were > added because without them there were certain cases that could > either segfault or result in an infinite loop. > > --David
This exception is quite old: --- changeset: 17597:32e7d0898eab branch: legacy-trunk user: Guido van Rossum <gu...@python.org> date: Fri Apr 20 19:13:02 2001 +0000 files: Include/Python.h Include/abstract.h Include/object.h Include/opcode.h Include/pyerrors.h Lib/dis.py Makefile.pre.in Objects/abstra description: Iterators phase 1. This comprises: new slot tp_iter in type object, plus new flag Py_TPFLAGS_HAVE_ITER new C API PyObject_GetIter(), calls tp_iter new builtin iter(), with two forms: iter(obj), and iter(function, sentinel) new internal object types iterobject and calliterobject new exception StopIteration new opcodes for "for" loops, GET_ITER and FOR_ITER (also supported by dis.py) new magic number for .pyc files new special method for instances: __iter__() returns an iterator iteration over dictionaries: "for x in dict" iterates over the keys iteration over files: "for x in file" iterates over lines TODO: documentation test suite decide whether to use a different way to spell iter(function, sentinal) decide whether "for key in dict" is a good idea use iterators in map/filter/reduce, min/max, and elsewhere (in/not in?) speed tuning (make next() a slot tp_next???) --- More recently, I added another exception if a dictionary is modified during a lookup. When I proposed a new frozendict type to secure my pysandbox project, Armin Rigo wrote that CPython segfaults must be fixed. So I fixed a corner case on dictionaries. http://bugs.python.org/issue14205 Thread in python-dev: https://mail.python.org/pipermail/python-dev/2012-March/117290.html The discussion in http://bugs.python.org/issue14205 is interesting. Victor _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
