forked from Lephenixnoir/PythonExtra
44 lines
1.0 KiB
Python
44 lines
1.0 KiB
Python
# object.__new__(cls) is the only way in Python to allocate empty
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# (non-initialized) instance of class.
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# See e.g. http://infohost.nmt.edu/tcc/help/pubs/python/web/new-new-method.html
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# TODO: Find reference in CPython docs
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try:
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# If we don't expose object.__new__ (small ports), there's
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# nothing to test.
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object.__new__
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except AttributeError:
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print("SKIP")
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raise SystemExit
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class Foo:
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def __new__(cls):
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# Should not be called in this test
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print("in __new__")
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raise RuntimeError
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def __init__(self):
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print("in __init__")
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self.attr = "something"
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o = object.__new__(Foo)
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#print(o)
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print("Result of __new__ has .attr:", hasattr(o, "attr"))
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print("Result of __new__ is already a Foo:", isinstance(o, Foo))
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o.__init__()
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#print(dir(o))
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print("After __init__ has .attr:", hasattr(o, "attr"))
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print(".attr:", o.attr)
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# should only be able to call __new__ on user types
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try:
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object.__new__(1)
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except TypeError:
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print("TypeError")
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try:
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object.__new__(int)
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except TypeError:
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print("TypeError")
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