78 lines
1.4 KiB
Python
78 lines
1.4 KiB
Python
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"""
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Commonly used hooks for on_setattr.
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"""
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from __future__ import absolute_import, division, print_function
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from . import _config
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from .exceptions import FrozenAttributeError
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def pipe(*setters):
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"""
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Run all *setters* and return the return value of the last one.
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.. versionadded:: 20.1.0
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"""
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def wrapped_pipe(instance, attrib, new_value):
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rv = new_value
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for setter in setters:
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rv = setter(instance, attrib, rv)
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return rv
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return wrapped_pipe
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def frozen(_, __, ___):
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"""
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Prevent an attribute to be modified.
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.. versionadded:: 20.1.0
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"""
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raise FrozenAttributeError()
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def validate(instance, attrib, new_value):
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"""
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Run *attrib*'s validator on *new_value* if it has one.
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.. versionadded:: 20.1.0
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"""
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if _config._run_validators is False:
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return new_value
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v = attrib.validator
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if not v:
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return new_value
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v(instance, attrib, new_value)
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return new_value
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def convert(instance, attrib, new_value):
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"""
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Run *attrib*'s converter -- if it has one -- on *new_value* and return the
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result.
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.. versionadded:: 20.1.0
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"""
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c = attrib.converter
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if c:
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return c(new_value)
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return new_value
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NO_OP = object()
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"""
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Sentinel for disabling class-wide *on_setattr* hooks for certain attributes.
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Does not work in `pipe` or within lists.
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.. versionadded:: 20.1.0
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"""
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