Source code for c4dtools.misc.userdata

# coding: utf-8
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# Copyright (c) 2012-2013, Niklas Rosenstein
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r"""
c4dtools.misc.userdata
~~~~~~~~~~~~~~~~~~~~~~

Module for interacting with Cinema 4D's UserData interface.
"""

import c4d
import copy

class UserDataSetAndGet(object):
    r"""
    This class manages userdata-value retrieval and storing.
    It accepts a dictionary associating the attribute-name and
    the userdata's sub-id on initialization and the c4d.BaseList2D
    object to use for retrival and storing.

    The values can optionally be cached to improve value retrieval.

    .. code-block:: python

        from c4dtools.misc.userdata import UserDataSetAndGet as UDSG
        data = UDSG({
            'count': 1,
            'link': 2,
        }, op)
        print data.count
        print data.link
        # Equal to
        print op[c4d.ID_USERDATA, 1]
        print op[c4d.ID_USERDATA, 2]
    """

    __slots__ = '_fields _op _cache _do_caching'.split()

    def __init__(self, fields, op, do_caching=True):
        super(UserDataSetAndGet, self).__init__()
        self._fields = copy.copy(fields)
        self._op = op
        self._cache = {}
        self._do_caching = do_caching

    def __getattr__(self, name):
        if name not in self._fields:
            raise AttributeError('no userdata-field %r defined.' % name)
        if self._do_caching and name in self._cache:
            return self._cache[name]
        value = self._op[c4d.ID_USERDATA, self._fields[name]]
        if self._do_caching:
            self._cache[name] = value
        return value

    def __setattr__(self, name, value):
        if name in self.__slots__:
            super(UserDataSetAndGet, self).__setattr__(name, value)
            return
        elif name not in self._fields:
            raise AttributeError('no userdata-field %r defined.' % name)

        self._op[c4d.ID_USERDATA, self._fields[name]] = value
        if self._do_caching:
            getattr(self, name)

    def clear_cache(self):
        r"""
        Clear the cached values. Call this in case the host object's
        parameters have changed by not using the instance of this class.
        """
        self._cache = {}