[openstack-dev] [neutron][all] Naming convention for unused variables

Vishvananda Ishaya vishvananda at gmail.com
Wed Oct 15 15:05:46 UTC 2014


On Oct 13, 2014, at 6:28 PM, Angus Lees <gus at inodes.org> wrote:

> (Context: https://review.openstack.org/#/c/117418/)
> 
> I'm looking for some rough consensus on what naming conventions we want for 
> unused variables in Neutron, and across the larger OpenStack python codebase 
> since there's no reason for Neutron to innovate here.
> 
> As far as I can see, there are two cases:
> 
> 
> 1.  The "I just don't care" variable
> 
> Eg:    _, _, filename = path.rpartition('/')
> 
> In python this is very commonly '_', but this conflicts with the gettext 
> builtin so we should avoid it in OpenStack.
> 
> Possible candidates include:
> 
> a.  'x'
> b. '__'  (double-underscore) 
> c. No convention
> 
> 
> 2.  "I know it is unused, but the name still serves as documentation"
> 
> Note this turns up as two cases: as a local, and as a function parameter.
> 
> Eg:   out, _err = execute('df', path)
> 
> Eg:   def makefile(self, _mode, _other):
>            return self._buffer
> 
> I deliberately chose that second example to highlight that the leading-
> underscore convention collides with its use for private properties.
> 
> Possible candidates include:
> 
> a. _foo   (leading-underscore, note collides with private properties)
> b. unused_foo   (suggested in the Google python styleguide)
> c. NOQA_foo   (as suggested in c/117418)
> d. No convention  (including not indicating that variables are known-unused)

I prefer a. Private properties are explicitly prefixed with self. so it
doesn’t seem to be a conflict to me.

Vish

> 
> 
> As with all style discussions, everyone feels irrationally attached to their 
> favourite, but the important bit is to be consistent to aid readability  (and 
> in this case, also to help the mechanical code checkers).
> 
> Vote / Discuss / Suggest additional alternatives.
> 
> -- 
> - Gus
> 
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> OpenStack-dev at lists.openstack.org
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