[sane-devel] [RFC] how to enable 1.1 features

[Alessandro Zummo]

On Thu, 28 Feb 2008 08:43:26 +0900
Olaf Meeuwissen <olaf.meeuwissen at avasys.jp> wrote:

> Alessandro Zummo <azummo-lists at towertech.it> writes:
> 
> >   please see the attached patch regarding my proposal
> >  for a safe enabling of 1.1 features in the backends.
>
> Hmm, the SANE Standard Version 1.03 says about SANE_VERSION_CODE():
> 
>   Note that the major version number alone determines whether a
>   frontend/backend pair is compatible.  The minor version and the
>   build revision are used for informational and bug-fixing purposes
>   only.
> 
> This means that a backend implementer is free to pass back something
> like
> 
>   SANE_VERSION_CODE(1,2,3)
> 
> for a SANE 1.0 backend.  Isn't that a bit confusing?  I think that
> just changing the name of the macro to something like SANE_API_LEVEL
> would improve code readability and reduce confusion.

 yes, SANE_API_LEVEL sounds better. The 1.1 standar will have
 to mention this.

> 
> The same SANE Standard Version 1.03 does not explicitly state what a
> backend is supposed to return when passed and unknown action.  I'd
> assume that any sane developer would return SANE_STATUS_UNSUPPORTED
> but I wouldn't quite bet on it.

 neither do I, that's why I will be checking every backend. UNSUPPORTED
 would be fine but any error would do. The 1.1 standard will mention that too.
 
> Another issue I have with the SANE_ACTION_COMPAT_LEVEL symbol is that
> I don't think of that as an action.  A symbol more action-like, like
> SANE_ACTION_CHECK_API_LEVEL for example, is clearer IMHO.

 ack.


> Apart from the above (and the fact that it is an ugly hack as SANE 1.0
> surely didn't intend to provide for API major/minor versions ;-), the
> above would work fine in practice.

 We all noticed that SANE 1.0 missed some things.. that's the reason
 we are still discussing all of that 10 years after :-D


-- 

 Best regards,

 Alessandro Zummo,
  Tower Technologies - Torino, Italy

  http://www.towertech.it