[issue40890] Dict views should be introspectable

Change by Pablo Galindo Salgado : -- nosy: -pablogsal ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue40890] Dict views should be introspectable

Change by Joshua Bronson : -- nosy: +jab nosy_count: 6.0 -> 7.0 pull_requests: +27187 pull_request: https://github.com/python/cpython/pull/28892 ___ Python tracker ___

[issue40890] Dict views should be introspectable

Change by Serhiy Storchaka : -- stage: patch review -> resolved status: open -> closed ___ Python tracker ___ ___ Python-bugs-list

[issue40890] Dict views should be introspectable

Pablo Galindo Salgado added the comment: New changeset 10c3b2120afa01b2c310ac50e99d8b98c943b0a2 by Pablo Galindo in branch 'master': bpo-40890: Fix compiler warning in dictobject.c (GH-20876) https://github.com/python/cpython/commit/10c3b2120afa01b2c310ac50e99d8b98c943b0a2 --

[issue40890] Dict views should be introspectable

Change by Pablo Galindo Salgado : -- nosy: +pablogsal nosy_count: 5.0 -> 6.0 pull_requests: +20064 pull_request: https://github.com/python/cpython/pull/20876 ___ Python tracker

[issue40890] Dict views should be introspectable

Change by Dennis Sweeney : -- pull_requests: +20061 stage: resolved -> patch review pull_request: https://github.com/python/cpython/pull/20873 ___ Python tracker ___

[issue40890] Dict views should be introspectable

Serhiy Storchaka added the comment: There is a tiny portability issue. -- status: closed -> open ___ Python tracker ___ ___

[issue40890] Dict views should be introspectable

Change by Raymond Hettinger : -- resolution: -> fixed stage: patch review -> resolved status: open -> closed ___ Python tracker ___

[issue40890] Dict views should be introspectable

Raymond Hettinger added the comment: New changeset 3ee0e48b0376a710c08eec6f30e4181563b192a2 by Dennis Sweeney in branch 'master': bpo-40890: Add `mapping` property to dict views (GH-20749) https://github.com/python/cpython/commit/3ee0e48b0376a710c08eec6f30e4181563b192a2 --

[issue40890] Dict views should be introspectable

Dennis Sweeney added the comment: Would it be better to have a dictview.mapping() method rather than an attribute, since it constructs a new object of a different type and since that's what keys(), values(), and items() are? -- ___ Python tracker

[issue40890] Dict views should be introspectable

Inada Naoki added the comment: +1. -- ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue40890] Dict views should be introspectable

Raymond Hettinger added the comment: > I meant that you can make dict_view.mapping always > returning a MappingProxyType. That would be a reasonable constraint. -- ___ Python tracker

[issue40890] Dict views should be introspectable

Serhiy Storchaka added the comment: I meant that you can make dict_view.mapping always returning a MappingProxyType. -- ___ Python tracker ___

[issue40890] Dict views should be introspectable

Dennis Sweeney added the comment: Here's a workaround that's possible with PR 20749 applied: >>> d = {"a":1, "b":2} # fill up the dict... >>> DICT = object() >>> d[DICT] = d >>> items = d.items() >>> del d >>> >>> d = items.mapping[DICT].pop(DICT) >>> d {'a': 1, 'b': 2} --

[issue40890] Dict views should be introspectable

Dennis Sweeney added the comment: PR 20749 gives each dict view access to a mappingproxy for the original dict, although I don't know if that defeats the original purpose. It might be hard to sensibly make MappingProxy(d).items() return something other than d.items(), since this is already

[issue40890] Dict views should be introspectable

Change by Dennis Sweeney : -- keywords: +patch pull_requests: +19954 pull_request: https://github.com/python/cpython/pull/20749 ___ Python tracker ___

[issue40890] Dict views should be introspectable

Raymond Hettinger added the comment: Do you see any easy way to have some_mapping_proxy.items().mapping return some_mapping_proxy rather than unmasking the proxied dict? -- keywords: -easy (C), patch ___ Python tracker

[issue40890] Dict views should be introspectable

Rémi Lapeyre added the comment: property, partial, bound methods and ChinMap all do something complex with the underlying object. Dict-views are quite simple by comparison, is there an example where this would be helpful and better than just passing directly the mapping object? --

[issue40890] Dict views should be introspectable

Inada Naoki added the comment: > Would the best way to address this be adding new KeysProxy, ValuesProxy, and > ItemsProxy types? I feel it is too much. Until real high need is demonstrated, I don't want to introduce such complexity. -- nosy: +inada.naoki

[issue40890] Dict views should be introspectable

Serhiy Storchaka added the comment: I am not sure that it is good idea to expose internal details (do you want to expose also internal details of iterators?), but if expose an underlying dict of a dict view, I think it should be either a copy or a read-only proxy. It should be enough to

[issue40890] Dict views should be introspectable

Dennis Sweeney added the comment: Would the best way to address this be adding new KeysProxy, ValuesProxy, and ItemsProxy types? -- ___ Python tracker ___

[issue40890] Dict views should be introspectable

Dennis Sweeney added the comment: Indeed, with PR 20691 applied, the following crashes: >>> vars(str).items().mapping.clear() >>> "uh oh" -- ___ Python tracker ___

[issue40890] Dict views should be introspectable

Change by Dennis Sweeney : -- keywords: +patch pull_requests: +19906 stage: -> patch review pull_request: https://github.com/python/cpython/pull/20691 ___ Python tracker ___

[issue40890] Dict views should be introspectable

Dennis Sweeney added the comment: I think this will also require typing.MappingProxyType to change a bit, since it would make a proxy's underlying dict accessible: >>> d = dict() >>> proxy = MappingProxyType(d) >>> type(proxy.items()) is type(d.items()) # should be False

[issue40890] Dict views should be introspectable

Raymond Hettinger added the comment: Just "mapping" would suffice. That is variable name used in the ABCs, the name defined in the glossary, and the variable name used in ChainMap (in plural form). -- ___ Python tracker

[issue40890] Dict views should be introspectable

Dennis Sweeney added the comment: I'd be happy to write a PR. Method names could be "mapping", "target", "target_mapping", "target_dict", "referent_dict", etc. I like the choice of "target_mapping": d = dict() assert d is d.keys().target_mapping assert d is

[issue40890] Dict views should be introspectable

New submission from Raymond Hettinger : Dict views wrap an underlying mapping but don't expose that mapping as an attribute. Traditionally, we do expose wrapped objects: property() exposes fget, partial() exposes func, bound methods expose __func__, ChainMap() exposes maps, etc. Exposing