autoprops.py 文件源码

def _add_contract_to_setter(setter_fun, var_name, property_contract, property_name):

    # 0. check that we can import contracts
    try:
        # noinspection PyUnresolvedReferences
        from contracts import ContractNotRespected, contract
    except ImportError as e:
        raise Exception('Use of _add_contract_to_setter requires that PyContract library is installed. Check that you '
                        'can \'import contracts\'')

    # -- check if a contract already exists on the function
    if hasattr(setter_fun, '__contracts__'):
        msg = 'overridden setter for attribute ' + property_name + ' implemented by function ' \
              + str(setter_fun.__qualname__) + ' has a contract while there is a contract already defined ' \
              + 'for this property in the __init__ constructor. This will lead to double-contract in the final ' \
              + 'setter, please remove the one on the overridden setter.'
        warn(msg)

    # -- add the generated contract
    setter_fun_with_possible_contract = contract(setter_fun, **{var_name: property_contract})

    # the only thing we can't do is to replace the function's parameter name dynamically in the error messages
    # so we wrap the function again to catch the potential pycontracts error :(
    # old:
    # @functools.wraps(func) -> to make the wrapper function look like the wrapped function
    # def wrapper(self, *args, **kwargs):
    # new:
    # we now use 'decorate' to have a wrapper that has the same signature, see below
    def _contracts_parser_interceptor(func, self, *args, **kwargs):
        try:
            return func(self, *args, **kwargs)
        except ContractNotRespected as er:
            er.error = er.error.replace('\'val\'', '\'' + property_name + '\'')
            raise er

    # f = _contracts_parser_interceptor(f)
    setter_fun_with_possible_contract = decorate(setter_fun_with_possible_contract, _contracts_parser_interceptor)
    return setter_fun_with_possible_contract