gistfile1.py

_DEFAULT_PORT = 1234

class SomeProtocol:
    ...
    def __enter__(self):
        self._client = socket()
        self._client.connect(
            (self.host,
            self.port or _DEFAULT_PORT)
        )
        return self  

# If you want to subclass SomeProtocol, you would have to overwrite every method!

# Better
class SomeProtocol:
    _default_port = 1234
    ...
    def __enter__(self):
        self._client = socket()
        self._client.connect(
            (self.host,
            self.port or self._default_port))

@sloria, looks like you got a typo on line 12?

edit: looks like another type on line 14:

would have to overwrite very method!

Should very be every?

Fixed. Thanks.