[Python-ideas] Expose a child factory using MappingProxyType in builtins

[Ivan Levkivskyi]

Searching MappingProxyType on GitHub gives over 10,000 results.
I think it probably makes sense to make mappingproxy more "visible",
maybe move it to collections module? (where OrderedDict lives)

I am not sure if it makes sense to move it to builtins. (for comparison
frozenset gives around 1000,000 results)

--
Ivan



On 28 February 2017 at 16:24, Joseph Hackman <josephhackman at gmail.com>
wrote:

> +1
>
> I think this makes a lot of sense. What would you name the built in?
>
> -Joseph
>
> > On Feb 28, 2017, at 7:17 AM, Michel Desmoulin <desmoulinmichel at gmail.com>
> wrote:
> >
> > We have the immutable frozenset for sets and and tuples for lists.
> >
> > But we also have something to manipulate dict as immutable
> datastructures:
> >
> >>>> from types import MappingProxyType as idict
> >>>> d = idict({'a':1, 'b':2, 'c':3})
> >>>> d['a'] = 4
> > Traceback (most recent call last):
> >  File "<ipython-input-3-c6f93d6278af>", line 1, in <module>
> >    d['a'] = 4
> > TypeError: 'mappingproxy' object does not support item assignment
> >
> > We could expose this as a built type to allow the last of the most
> > important data structure in Python to be easily immutable.
> >
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