kicad-developers team mailing list archive

[Wayne Stambaugh <stambaughw@xxxxxxxxx>]

On 11/24/2017 05:01 PM, hauptmech wrote:
> On 25/11/17 02:14, Wayne Stambaugh wrote:
>> This is *the* fatal flaw with the cache library.  User's assume it is
>> stale symbols or a temporary copy.  It is not.  It is a snapshot of the
>> current library symbols linked to the symbols in the schematic.  It gets
>> refreshed every time the schematic is saved.  Once you delete this file
>> or keep an out of date copy using cvs, all bets are off.  It is only a
>> matter of time before one of your symbol libraries changes or gets
>> removed and you will end up with a broken schematic.  The rescue code
>> depends on the cache being up to date in order preserve you schematic.
>> If the cache is not current, the rescuing cannot be guaranteed.
> 
> I don't think it's necessarily a flaw. And your description above is
> indeed a cache. That's not a bad thing. I recall that I left it out of
> version control because I wanted to make sure fixes to my symbols were
> always propagated to the design. In the repo I'm referencing for this
> discussion I had 10 project files all using the same local library. I
> didn't want to have to manually update each schematic to propagate
> changes. Deleting untracked files was what I did instead. At the time no
> one was making breaking changes to system installed symbols, so the
> system libs were stable for this workflow.
> 
> I'm trying think of the least effort way to migrate an old design in
> these circumstances.
> 
> Can we have the rescue code fail if no cache file is found? That at
> least lets the user know they are in uncharted territory. Then if a lot
> of users come complaining you will know if it is worth doing a bit more
> in the rescue code.
> 
> If the cache is not available during rescue you can load a copy of the
> libraries that were current at the schematic save date and either
> re-cache them or rescue them directly. But this is only worth doing if a
> significant number of users are affected.

AFAIK, the rescue code doesn't do anything if there is not cache file
because the cache file is used for the comparison.  I actually
considered adding a check on schematic load to warn the user with a list
of all of symbols linked to the cache library so they could fix them.
I'm not sure this is desirable but at least users would know that
symbols were missing from their libraries and the links were falling
back to the cache which is tenuous at best.