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128420359e
Currently, dict views (eg `dict.keys()`, `dict.values()`) do not implement
the `bool` or `len` unary operations. That may seem like a reasonable
omission for MicroPython to keep code size down, but it actually leads to
silently incorrect bool operations, because by default things are true.
Eg we currently have:
>>> bool(dict().keys())
True
which is wrong, it should be `False` because the dict is empty.
This commit implements `bool` and `len` unary operations on dict views by
simply delegating to the existing dict unary op function.
Fixes issue #12385.
Signed-off-by: Damien George <damien@micropython.org>
45 lines
831 B
Python
45 lines
831 B
Python
d = {1: 2}
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for m in d.items, d.values, d.keys:
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print(m())
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print(list(m()))
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# print a view with more than one item
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print({1:1, 2:1}.values())
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# `bool` and `len` unary ops
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for d in ({}, {1: 2}, {1: 2, 3: 4}):
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for op in (bool, len):
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print(op(d.keys()), op(d.values()), op(d.items()))
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# unsupported binary op on a dict values view
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try:
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{1:1}.values() + 1
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except TypeError:
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print('TypeError')
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# unsupported binary op on a dict keys view
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try:
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{1:1}.keys() + 1
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except TypeError:
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print('TypeError')
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# keys dict_view is not hashable
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try:
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hash({}.keys())
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except TypeError:
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print('TypeError')
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# values dict_view is hashable
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print(type(hash({}.values())))
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# items dict_view is not hashable
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try:
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hash({}.items())
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except TypeError:
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print('TypeError')
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# set operations still to come
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