Re: [Qemu-devel] [PATCH] qom: helper macro for adding read-only properties

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Sep 16, 2013 at 06:07:33PM +0200, Paolo Bonzini wrote:
> Il 16/09/2013 18:01, Michael S. Tsirkin ha scritto:
> > On Mon, Sep 16, 2013 at 05:56:56PM +0200, Paolo Bonzini wrote:
> >> Il 16/09/2013 17:48, Michael S. Tsirkin ha scritto:
> >>> http://sweng.the-davies.net/Home/rustys-api-design-manifesto
> >>>
> >>> Even then: it will be at best
> >>> "5. Do it right or it will always break at runtime."
> >>>
> >>> We need to switch to APIs at
> >>> "9. The compiler/linker won't let you get it wrong."
> >>
> >> We definitely can get at least to "make check won't let you get it
> >> wrong", which is somewhere in the middle.
> >>
> >> Paolo
> > 
> > We can't.
> > make check just runs unit tests.
> > So it can catch changes, but it can not catch bugs in new
> > interfaces.
> 
> We can have "make check" run QEMU once for each board, which would trap
> things that will always break at runtime such as a misspelled property.
>  Similarly, we could have tests that try to instantiate every device,
> even if they do not do anything with the guest-visible device.  Such
> dummy tests can catch bugs in interface changes.

They won't catch bugs for properties that
1. change after device is instanciated
2. are accessed after device is instanciated

> I look forward to discussing the future of qos and qtest at KVM Forum... :)
> 
> Paolo

This is not the topic I started really.

Testing isn't a replacement for type safety.

C is a compiled language for a reason, qom
needs a set of wrappers to get that back,
strings should only be used for external interfaces.

-- 
MST