[Python-Dev] Issue 14417: consequences of new dict runtime error (original) (raw)

Etienne Robillard animelovin at gmail.com
Sat Mar 31 13:43:28 CEST 2012

The frozendict builtin type was rejected, but we are going to add types.MappingProxyType: see issue #14386. types.MappingProxyType(mydict.copy()) is very close to the frozendict builtin type.

Victor

Thanks, Victor. :)

Will this mean the new dict subclass for CPython will not expose dictproxy to favorize a new types.MappingProxyType type to emulate immutable-like types ? What could be then consequences for code still expecting a non-mutable dict() type ? Therefore I guess this ticket provides more than just speculating points to reconsider such aliased types in cpython.

I also found this article quite useful: http://www.cs.toronto.edu/~tijmen/programming/immutableDictionaries.html

Yet I might miss how this "new dict" type could potentially induce a RuntimeError unless in python 3.3 a new dict proxy alias is introduced to perform invariant operations in non thread-safe code.

Regards, Etienne

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