New submission from Larry Hastings:
The documentation for Inspect.Signature and Inspect.Parameter states that the
objects are immutable. And they go to great lengths to provide a convenient
interface allowing you to "replace" members.
However, the objects make only a pathetic effort at being immutable. They hide
their public API members (e.g. "name") behind a property, which they store
internally in a member prefixed with an underscore (e.g. "_name"). BUT THE
INTERNAL MEMBER IS EXTERNALLY MUTABLE.
Example code:
>>> def foo(i=3): pass
>>> sig = inspect.signature(foo)
>>> str(sig)
'(i=3)'
>>> sig.parameters['i']._name ='silly'
>>> str(sig)
'(silly3)'
----------
components: Library (Lib)
messages: 184796
nosy: brett.cannon, larry
priority: low
severity: normal
stage: test needed
status: open
title: inspect.Signature and inspect.Parameter objects are mutable
type: behavior
versions: Python 3.3, Python 3.4
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Python tracker <[email protected]>
<http://bugs.python.org/issue17499>
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