@classmethod
def getSize(cls, policy, size, sizeList):
    """Get the correct size based on the given resize policy.

        * resizePolicy -- The resize policy
        * size -- The main single size (width or height) of the widget
        * sizeList -- The list of the single dimension size (widths or heights)
                      of widgets's children

        """
    policyMap = {cls.Fixed: cls.__getFixedSize, cls.Expanding: cls.
        __getExpandingSize}
    policyFn = policyMap.get(policy)
    if policyFn is not None:
        return policyFn(size, sizeList)
    else:
        raise Exception('Unknown Policy [%s]' % policy)
