Source code for attributes

#
##
##  This file is part of pyFormex 1.0.5  (Sat Feb 16 10:40:32 CET 2019)
##  pyFormex is a tool for generating, manipulating and transforming 3D
##  geometrical models by sequences of mathematical operations.
##  Home page: http://pyformex.org
##  Project page:  http://savannah.nongnu.org/projects/pyformex/
##  Copyright 2004-2018 (C) Benedict Verhegghe (benedict.verhegghe@ugent.be)
##  Distributed under the GNU General Public License version 3 or later.
##
##  This program is free software: you can redistribute it and/or modify
##  it under the terms of the GNU General Public License as published by
##  the Free Software Foundation, either version 3 of the License, or
##  (at your option) any later version.
##
##  This program is distributed in the hope that it will be useful,
##  but WITHOUT ANY WARRANTY; without even the implied warranty of
##  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
##  GNU General Public License for more details.
##
##  You should have received a copy of the GNU General Public License
##  along with this program.  If not, see http://www.gnu.org/licenses/.
##
"""Attributes

This module defines a general class for adding extra attributes to
other objects without cluttering the name space.
"""
from __future__ import absolute_import, division, print_function


from pyformex.mydict import Dict, returnNone
from pyformex import utils


[docs]class Attributes(Dict): """A general class for holding attributes. This class is a versatile dict class for objects that need a customizable set of attributes, while avoiding a wildly expanding name space. The class has dict type and object/attribute type syntax. Furthermore, an instance can be called as a function to populate or update its contents. Giving an attribute the value None removes it from the dict. Any non-existing attribute returns None. Parameters: - `data`: a dict or any other object that can be used to initialize a :class:`Dict`. This provides the data stored in the Attributes. - `default`: either another Attributes instance, or None. If another Attributes is specified, keys not existing in `self` will be looked up in `default` and that value will be returned. Example: >>> A = Attributes() >>> print(A) {} >>> A(color='red',alpha=0.7,ontop=True) >>> print(A) {'alpha': 0.7, 'color': 'red', 'ontop': True} >>> A.ontop = None >>> A.alpha = 0.8 >>> print(A) {'alpha': 0.8, 'color': 'red'} >>> B = Attributes({'color':'green'},default=A) >>> print(B) {'color': 'green'} >>> print(B.color,B.alpha) green 0.8 >>> A.clear() >>> print(A) {} >>> print(B.color,B.alpha) green None >>> B(color=None,alpha=1.0) >>> print(B) {'alpha': 1.0} >>> B['alpha'] = None >>> print(B) {} """ def __init__(self,data={},default=None): """Create a new Attributes dict""" if isinstance(default, Attributes): self._default_dict_ = default default = self._return_default_ elif default is None: default = returnNone elif callable(default): pass else: raise ValueError("The 'default' argument should be an Attributes instance or None; got %s:" % type(default)) default = returnNone Dict.__init__(self, data, default) def __call__(self,**kargs): for k in kargs: setattr(self,k,kargs[k]) # update = __call__ def __setitem__(self, key, value): if value is None: if key in self: del self[key] else: Dict.__setitem__(self, key, value) __setattr__ = __setitem__ def _return_default_(self, key): return self._default_dict_[key] def __repr__(self): """Create a string representation of the Attributes. This will print the Attributes in a format like a dict, but with the keys sorted, and the _default_dict_ item is not printed. """ return utils.dictStr(self,['_default_dict_' ])
# End