Reports as system-state Observers

[Christopher James Halse Rogers]

On Thu, Sep 15, 2016 at 11:57 AM, Daniel van Vugt 
<daniel.van.vugt at canonical.com> wrote:
> Not impossible, but it feels too ugly. I would prefer to keep reports 
> for debugging/logging only where they don't affect the behavior of 
> the server. And programmers can assume this is true without knowing 
> the implementation details of any given subsystem.

I agree, but
> 
> 
> The implementation is potentially also ugly. At each point where a 
> report happens you can't any more say:
>    report_interface->report_something()
> because that would only call one implementation. So we would need to 
> change the architecture of all reports and for consistency change 
> them all. It doesn't sound nice.

...this wouldn't actually be true? We'd just make 
the_report_interface() not an override point and instead always have 
the same implementation (which would then delegate to whichever report 
implementations have been registered).