optparse.py 文件源码

def _check_type(self):
        if self.type is None:
            if self.action in self.ALWAYS_TYPED_ACTIONS:
                if self.choices is not None:
                    # The "choices" attribute implies "choice" type.
                    self.type = "choice"
                else:
                    # No type given?  "string" is the most sensible default.
                    self.type = "string"
        else:
            # Allow type objects or builtin type conversion functions
            # (int, str, etc.) as an alternative to their names.  (The
            # complicated check of __builtin__ is only necessary for
            # Python 2.1 and earlier, and is short-circuited by the
            # first check on modern Pythons.)
            import __builtin__
            if ( type(self.type) is types.TypeType or
                 (hasattr(self.type, "__name__") and
                  getattr(__builtin__, self.type.__name__, None) is self.type) ):
                self.type = self.type.__name__

            if self.type == "str":
                self.type = "string"

            if self.type not in self.TYPES:
                raise OptionError("invalid option type: %r" % self.type, self)
            if self.action not in self.TYPED_ACTIONS:
                raise OptionError(
                    "must not supply a type for action %r" % self.action, self)