[New-bugs-announce] [issue24597] forbid redefinition of specializations in singledispatch

[Antoine Pitrou]

New submission from Antoine Pitrou:

singledispatch currently doesn't defend against unwanted redefinition of an existing specialization, e.g.:

>>> def f(x): return "default"
... 
>>> f = functools.singledispatch(f)
>>> @f.register(int)
... def _(x): return "1"
... 
>>> @f.register(int)
... def _(x): return "2"
... 
>>> f(42)
'2'

This can be annoying when used as an extension mechanism. It would be nice if at least an option in the singledispatch() constructor could prevent this.

----------
components: Library (Lib)
messages: 246493
nosy: lukasz.langa, ncoghlan, pitrou, rhettinger
priority: normal
severity: normal
status: open
title: forbid redefinition of specializations in singledispatch
type: enhancement
versions: Python 3.6

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue24597>
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