Util.py 文件源码

def silent_intern(x):
    """
    Perform sys.intern() on the passed argument and return the result.
    If the input is ineligible (e.g. a unicode string) the original argument is
    returned and no exception is thrown.
    """
    try:
        return sys.intern(x)
    except TypeError:
        return x



# From Dinu C. Gherman,
# Python Cookbook, second edition, recipe 6.17, p. 277.
# Also:
# http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/68205
# ASPN: Python Cookbook: Null Object Design Pattern

#TODO??? class Null(object):