Lichen

Annotated lib/__builtins__/attribute.py

933:520036942e1e
2021-06-28 Paul Boddie Removed "WikiWord" prevention syntax since MoinLight ignores it.
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#!/usr/bin/env python
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"""
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Attribute-related functions.
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Copyright (C) 2015, 2016 Paul Boddie <paul@boddie.org.uk>
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This program is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free Software
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Foundation; either version 3 of the License, or (at your option) any later
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version.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
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details.
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You should have received a copy of the GNU General Public License along with
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this program.  If not, see <http://www.gnu.org/licenses/>.
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"""
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from __builtins__.types import check_string
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from native import object_getattr
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_default=object() # a unique placeholder for a missing value
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def getattr(obj, name, default=_default):
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    """
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    Return for 'obj' the attribute having the given 'name', returning the given
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    'default' if the attribute is not defined for 'obj', raising an exception if
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    'default' is not indicated and the attribute is not defined.
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    """
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    check_string(name)
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    # Attempt to obtain the attribute. If the name is not recognised as an
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    # attribute name, the default will be returned. Otherwise, an access
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    # operation will be attempted.
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    try:
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        result = object_getattr(obj, name, default)
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    # Handle exceptions when the access operation fails.
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    except TypeError:
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        result = _default
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    # Check the result and, if it is the placeholder value, raise an exception.
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    if result is _default:
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        raise AttributeError(name)
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    # Otherwise, return the obtained value or supplied default.
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    else:
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        return result
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def hasattr(obj, name):
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    "Return whether 'obj' has an attribute called 'name'."
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    try:
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        getattr(obj, name)
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    except AttributeError:
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        return False
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    else:
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        return True
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# NOTE: setattr would probably only be supported on instances due to deductions
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# NOTE: applying to static objects being undermined by dynamic modifications.
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def setattr(obj, name, value):
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    raise NotImplementedError, "setattr"
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