root / lib / outils.py @ 185192f2
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# Copyright (C) 2012 Google Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301, USA.
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"""Module for object related utils."""
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#: Supported container types for serialization/de-serialization (must be a
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#: tuple as it's used as a parameter for C{isinstance})
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_SEQUENCE_TYPES = (list, tuple, set, frozenset) |
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class AutoSlots(type): |
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"""Meta base class for __slots__ definitions.
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"""
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def __new__(mcs, name, bases, attrs): |
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"""Called when a class should be created.
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@param mcs: The meta class
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@param name: Name of created class
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@param bases: Base classes
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@type attrs: dict
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@param attrs: Class attributes
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"""
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assert "__slots__" not in attrs, \ |
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"Class '%s' defines __slots__ when it should not" % name
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attrs["__slots__"] = mcs._GetSlots(attrs)
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return type.__new__(mcs, name, bases, attrs) |
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@classmethod
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def _GetSlots(mcs, attrs): |
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"""Used to get the list of defined slots.
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@param attrs: The attributes of the class
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"""
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raise NotImplementedError |
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class ValidatedSlots(object): |
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"""Sets and validates slots.
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"""
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__slots__ = [] |
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def __init__(self, **kwargs): |
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"""Constructor for BaseOpCode.
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The constructor takes only keyword arguments and will set
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attributes on this object based on the passed arguments. As such,
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it means that you should not pass arguments which are not in the
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__slots__ attribute for this class.
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"""
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slots = self.GetAllSlots()
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for (key, value) in kwargs.items(): |
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if key not in slots: |
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raise TypeError("Object %s doesn't support the parameter '%s'" % |
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(self.__class__.__name__, key))
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setattr(self, key, value) |
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@classmethod
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def GetAllSlots(cls): |
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"""Compute the list of all declared slots for a class.
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"""
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slots = [] |
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for parent in cls.__mro__: |
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slots.extend(getattr(parent, "__slots__", [])) |
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return slots
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def Validate(self): |
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"""Validates the slots.
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This method returns L{None} if the validation succeeds, or raises
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an exception otherwise.
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@rtype: NoneType
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@return: L{None}, if the validation succeeds
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@raise Exception: validation fails
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This method must be implemented by the child classes.
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"""
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raise NotImplementedError |
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def ContainerToDicts(container): |
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"""Convert the elements of a container to standard Python types.
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This method converts a container with elements to standard Python types. If
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the input container is of the type C{dict}, only its values are touched.
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Those values, as well as all elements of input sequences, must support a
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C{ToDict} method returning a serialized version.
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@type container: dict or sequence (see L{_SEQUENCE_TYPES})
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"""
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if isinstance(container, dict): |
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ret = dict([(k, v.ToDict()) for k, v in container.items()]) |
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elif isinstance(container, _SEQUENCE_TYPES): |
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ret = [elem.ToDict() for elem in container] |
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else:
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raise TypeError("Unknown container type '%s'" % type(container)) |
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return ret
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def ContainerFromDicts(source, c_type, e_type): |
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"""Convert a container from standard python types.
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This method converts a container with standard Python types to objects. If
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the container is a dict, we don't touch the keys, only the values.
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@type source: None, dict or sequence (see L{_SEQUENCE_TYPES})
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@param source: Input data
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@type c_type: type class
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@param c_type: Desired type for returned container
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@type e_type: element type class
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@param e_type: Item type for elements in returned container (must have a
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C{FromDict} class method)
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"""
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if not isinstance(c_type, type): |
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raise TypeError("Container type '%s' is not a type" % type(c_type)) |
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if source is None: |
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source = c_type() |
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if c_type is dict: |
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ret = dict([(k, e_type.FromDict(v)) for k, v in source.items()]) |
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elif c_type in _SEQUENCE_TYPES: |
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ret = c_type(map(e_type.FromDict, source))
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else:
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raise TypeError("Unknown container type '%s'" % c_type) |
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return ret
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