One important difference between MappingProxyType and a "proper" frozendict, as analog to frozenset, is that MappingProxyType doesn't have any method to return mutated versions of itself.
On Thu, 11 Oct 2018 at 01:24, Steven D'Aprano <st...@pearwood.info> wrote: > Hi Philiip, and welcome, > > On Wed, Oct 10, 2018 at 12:04:48PM -0500, Philip Martin wrote: > > > I generally have used MappingProxyType as a way to set default mapping > > to a function or to set an empty mapping to a function. > > > I've created a gist with an example use case: > > > > https://gist.github.com/pmart123/493edf84d9aa61691ca7321325ebb6ab > > Please try to keep the discussion in one place (i.e. here), for the > benefit of the archives and for those who have email access but not > unrestricted web access. > > Can you explain (in English) your use-case, and why MappingProxyType > isn't suitable? If it *is* suitable, how does your proposal differ? > > If the only proposal is to rename types.MappingProxyType to a builtin > "frozendict", that's one thing; if the proposal is something else, you > should explain what. > > > > I've included an example of what code typically looks like when using > > MappingProxyType and what it could look like with a > > frozendict implementation. > > Wouldn't that be just: > > from types import MappingProxyType as frozendict > d = frozendict({'spam': 1, 'eggs': 2}) > > versus: > > d = frozendict({'spam': 1, 'eggs': 2}) > > Apart from the initial import, how would they be different? You want a > frozendict; the existing MappingProxyType provides a frozendict (with a > surprising name, but never mind...). Wouldn't you use them exactly the > same way? They both (I presume) offer precisely the same read-only > access to the mapping interface. > > > > -- > Steve > _______________________________________________ > Python-ideas mailing list > Python-ideas@python.org > https://mail.python.org/mailman/listinfo/python-ideas > Code of Conduct: http://python.org/psf/codeofconduct/ >
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