[openstack-dev] [nova][oslo] oslo.config and import chains

Matthew Booth mbooth at redhat.com
Thu Aug 7 16:27:58 UTC 2014

On 07/08/14 16:27, Kevin L. Mitchell wrote:
> On Thu, 2014-08-07 at 12:15 +0100, Matthew Booth wrote:
>> A (the?) solution is to register_opts() in foo before importing any
>> modules which might also use oslo.config.
> Actually, I disagree.  The real problem here is the definition of
> bar_func().  The default value of the parameter "arg" will likely always
> be the default value of foo_opt, rather than the configured value,
> because "CONF.foo_opt" will be evaluated at module load time.  The way
> bar_func() should be defined would be:
>         def bar_func(arg=None):
>             if not arg:
>                 arg = CONF.foo_opt
> That ensures that arg will be the configured value, and should also
> solve the import conflict.

That's different behaviour, because you can no longer pass arg=None. The
fix isn't to change the behaviour of the code.

Matthew Booth
Red Hat Engineering, Virtualisation Team

Phone: +442070094448 (UK)
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