On 1/18/2018 4:37 PM, Jason Swails wrote:
Hello!
I am running into a very perplexing issue that is very rare, but creeps up
and is crashing my app.
The root cause of the issue comes down to the following check returning
true:
isinstance([], collections.Mapping)
I confirmed that one *can* register 'list' as a Mapping so that the
above returns True. I also discovered that doing so does not change
Mapping._abc_registry.
Have you grepped the dependencies (snipped) for '.register'?
Alternatively, the abc module doc says
"""
Changed in version 3.4: To detect calls to register(), you can use the
get_cache_token() function.
...
abc.get_cache_token()
Returns the current abstract base class cache token.
The token is an opaque object (that supports equality testing)
identifying the current version of the abstract base class cache for
virtual subclasses. The token changes with every call to
ABCMeta.register() on any ABC.
"""
You could call this before, between, and after all your imports, and add
such calls to the guilty import.
--
Terry Jan Reedy
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