[New-bugs-announce] [issue40248] Proposed class for collections: dynamicdict

[Steele Farnsworth]

New submission from Steele Farnsworth <swfarnsworth at gmail.com>:

I have implemented a class in the C code of the collections module which has similar behavior to the defaultdict class. This class, dynamicdict, supplies values for keys that have not yet been added using a default factory callable, but unlike defaultdict, the missing key itself is passed to the callable. This code can be seen here: https://github.com/swfarnsworth/cpython/blob/3.8/Modules/_collectionsmodule.c#L2234

While this does introduce a lot of redundant code, I'm not sure how it could be done without copying the implementation of the defaultdict class and adjusting how the default factory is called. For example, I don't believe that it's possible to support both behaviors within the defaultdict class without breaking backwards compatibility or adding another parameter to the constructor for the defaultdict class.

I would be happy to further explain the concept, implementation, potential use cases, or anything else that might work towards the adoption of this feature.

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components: ctypes
messages: 366157
nosy: Steele Farnsworth
priority: normal
severity: normal
status: open
title: Proposed class for collections: dynamicdict
type: enhancement
versions: Python 3.9

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue40248>
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