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