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[Python-Dev] Proposal for Python 3.3: dependence injection

Antoine Pitrou solipsis at pitrou.net
Thu Mar 24 17:57:58 CET 2011 
On Thu, 24 Mar 2011 11:46:42 -0500
Benjamin Peterson <benjamin at python.org> wrote:

> 2011/3/24 Jesus Cea <jcea at jcea.es>:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > Hi, everybody.
> >
> > I want to test the dev community interest in modifying the stdlib to
> > ease dependence injection.
> 
> I, for one, am -1. Code shouldn't be uglified for the purposes of
> testing. It's also a slippery slope. Maybe we should add parameters
> for open() and io functions? What about sys and os? Those often need
> to be mocked.

A non-ugly way of doing "dependency injection" is to rely on
class/instance attributes instead. e.g.:

class FTP:
    socket_factory = socket.create_connection

    def open(self, host, port):
        self.sock = self.socket_factory(host, port)
        ...


Regards

Antoine.
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