imputil.py 文件源码

def _import_fromlist(self, package, fromlist):
        'Import any sub-modules in the "from" list.'

        # if '*' is present in the fromlist, then look for the '__all__'
        # variable to find additional items (modules) to import.
        if '*' in fromlist:
            fromlist = list(fromlist) + \
                       list(package.__dict__.get('__all__', []))

        for sub in fromlist:
            # if the name is already present, then don't try to import it (it
            # might not be a module!).
            if sub != '*' and not hasattr(package, sub):
                subname = "%s.%s" % (package.__name__, sub)
                submod = self._import_one(package, sub, subname)
                if not submod:
                    raise ImportError, "cannot import name " + subname