Python-ideas

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python-ideas@python.org

April 2014

72 participants
42 discussions

loosening the restriction on what types may be unpacked using the ** syntax
by Eric Snow April 3, 2014

April 3, 2014

The ** keyword arg unpacking syntax in function calls is useful. However, currently there is an explicit check for a mapping type (presumably PyMapping_Check). So you can pass an object to dict(), but that same object *may* not work for keyword arg unpacking. For example: >>> from collections import OrderedDict >>> def f(**kwargs): return kwargs ... >>> kwargs = ((chr(i), i) for i in range(65, 68)) >>> f(**kwargs) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: f() argument after ** must be a mapping, not generator >>> f(**OrderedDict(kwargs)) {'B': 66, 'A': 65, 'C': 67} I'd like to relax this restriction so that anything you can pass to dict is also valid for keyword arg unpacking. This would mean you don't have to first create a dict to wrap the object before passing it in. Thoughts? -eric

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Browser for mailing lists
by Richard Prosser April 1, 2014

April 1, 2014

I wanted to search this list (and other Python ones) but it is practically impossible to do so. So why not add a tool like http://markmail.org/search/?q=python to https://mail.python.org/mailman/listinfo/python-ideas or the like? I got this from http://openmeetings.apache.org/mail-lists.html Cheers, Richard

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