__init__.py 文件源码

def __len__(self):
        """Number of zAttributes in this variable

        @return: number of zAttributes in the CDF
                 which have entries for this variable.
        @rtype: int
        """
        length = 0
        count = ctypes.c_long(0)
        self._cdf_file._call(const.GET_, const.CDF_NUMATTRS_,
                             ctypes.byref(count))
        current = 0
        while current < count.value:
            candidate = zAttr(self._cdf_file, current)
            if not candidate.global_scope():
                if candidate.has_entry(self._zvar._num()):
                    length += 1
            current += 1
        return length