On Wed, Apr 15, 2020 at 7:37 AM Victor Stinner
Le mer. 15 avr. 2020 à 05:02, Raymond Hettinger
a écrit : I would like to make that functionality available to the JSON module (or just about anything else that accepts a custom dict) by adding the magic methods for mappings so that this works:
catalog = json.load(f, object_hook=SimpleNamespace)
print(catalog['clothing']['mens']['shoes']['extra_wide']['quantity']) # currently possible with dict()
print(catalog.clothing.mens.shoes.extra_wide.quantity])
# proposed with SimpleNamespace()
print(catalog.clothing.boys['3t'].tops.quantity
# would also be supported
It seems like there are many projects on PyPI which provide such features. A few examples:
* https://pypi.org/project/attrdict/ "mapping objects that allow their elements to be accessed both as keys and as attributes" * https://pypi.org/project/dictlib/ "Dictionary keys as object attributes" * https://pypi.org/project/objdict/ "An ObjDict supports all normal dict operations, but adds support for accessing and setting entries as attributes" * https://pypi.org/project/mydict/ "dict subclass which tries to act like JavaScript objects, so you can use the dot notation (d.foo) to access members of the object" * https://pypi.org/project/dpath/ "accessing and searching dictionaries via /slashed/paths ala xpath". Example: dpath.util.search(x, "a/b/[cd]") * etc.
There are many variants:
* Support nested dictionaries or not * "Path" as a string ala XPath using "/" or "." separator -versus- don't give a direct access into nested dictionaries * Optional default value when a key/attribute is missing * etc.
Is there a project on PyPI which already already been battle-tested and gained enough popularity to consider that it's now mature enough to enter the stdlib?
+1 that was my first reaction as well. We don't need this battery. If you wanted to make it a more general thing, introduce a special operator for it instead of overloading ".". Ex: copy Perl and adopt -> as the "lookup the name in a dictionary without typing quotes around the constant value" operator. (please don't!) by the time we're saying "JSON should decode into a structured format" we can also say very true things like "JSON data should be validated against a schema" at which point we're ultimately going to wind up reinventing https://googleapis.dev/python/protobuf/latest/google/protobuf/json_format.ht... and equivalent other things. -gps The problem is that so far, I see no clear "winner" of a "standard"
API. So maybe leaving such feature on PyPI is better for now. It seems like these projects are opinionated about what should be the "right" behavior :-)
And yeah, there are even more advanced tools like https://glom.readthedocs.io/
As I wrote in the issue, I would prefer to leave SimpleNamespace unchanged. If such feature lands into the stdlib, I would prefer it to be a new class.
Victor -- Night gathers, and now my watch begins. It shall not end until my death. _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-leave@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/XDFTMWK5... Code of Conduct: http://python.org/psf/codeofconduct/