Source code for ccpn.util.FrozenDict

"""
"""
#=========================================================================================
# Licence, Reference and Credits
#=========================================================================================
__copyright__ = "Copyright (C) CCPN project (http://www.ccpn.ac.uk) 2014 - 2020"
__credits__ = ("Ed Brooksbank, Luca Mureddu, Timothy J Ragan & Geerten W Vuister")
__licence__ = ("CCPN licence. See http://www.ccpn.ac.uk/v3-software/downloads/license")
__reference__ = ("Skinner, S.P., Fogh, R.H., Boucher, W., Ragan, T.J., Mureddu, L.G., & Vuister, G.W.",
                 "CcpNmr AnalysisAssign: a flexible platform for integrated NMR analysis",
                 "J.Biomol.Nmr (2016), 66, 111-124, http://doi.org/10.1007/s10858-016-0060-y")
#=========================================================================================
# Last code modification
#=========================================================================================
__modifiedBy__ = "$modifiedBy: Ed Brooksbank $"
__dateModified__ = "$dateModified: 2020-06-23 18:47:11 +0100 (Tue, June 23, 2020) $"
__version__ = "$Revision: 3.0.1 $"
#=========================================================================================
# Created
#=========================================================================================
__author__ = "$Author: Gary Thompson $"
__date__ = "$Date: 2017-04-07 10:28:41 +0000 (Fri, April 07, 2017) $"
#=========================================================================================
# Start of code
#=========================================================================================


# from https://stackoverflow.com/questions/2703599/what-would-a-frozen-dict-be
class FrozenDict(dict):
    def __init__(self, *args, **kwargs):
        self._hash = None
        super(FrozenDict, self).__init__(*args, **kwargs)

    def __hash__(self):
        if self._hash is None:
            self._hash = hash(tuple(sorted(self.items())))  # iteritems() on py2
        return self._hash

    def _immutable(self, *args, **kws):
        raise TypeError('cannot change object - object is immutable')

    __setitem__ = _immutable
    __delitem__ = _immutable
    pop = _immutable
    popitem = _immutable
    clear = _immutable
    update = _immutable
    setdefault = _immutable