[Python-Dev] Add a frozendict builtin type (original) (raw)

Mark Shannon mark at hotpy.org
Tue Feb 28 19:13:01 CET 2012

Victor Stinner wrote:

* frozendict values must be immutable, as dict keys Why? That may be useful, but an immutable dict whose values might mutate is also useful; by forcing that choice, it starts to feel too specialized for a builtin. Hum, I realized that calling hash(myfrozendict) on a frozendict instance is enough to check if a frozendict only contains immutable objects. And it is also possible to check manually that values are immutable before creating the frozendict. I also prefer to not check for immutability because it does simplify the code :-) $ diffstat frozendict-3.patch Include/dictobject.h | 9 + Lib/collections/abc.py | 1 Lib/test/testdict.py | 59 +++++++++++ Objects/dictobject.c | 256 ++++++++++++++++++++++++++++++++++++++++++------- Objects/object.c | 3 Python/bltinmodule.c | 1 6 files changed, 295 insertions(+), 34 deletions(-) The patch is quite small to add a new builtin type. That's because most of the code is shared with the builtin dict type. (But the patch doesn't include the documentation, it didn't write it yet.)

Could you create an issue for this on the tracker, maybe write a PEP. I don't think sending patches to this mailing list is the way to do this.

Would you mind taking a look at how your code interacts with PEP 412.

Cheers, Mark.

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