kicad-developers team mailing list archive

[John Beard <john.j.beard@xxxxxxxxx>]

On 08/05/14 15:53, Dick Hollenbeck wrote:
> 
>> That's exactly what I mean - older versions of KiCad should be able to 
>> ignore, but retain, unknown data.
> 
> This sentence has two concepts in it.  One is fools gold, the other is poorly expressed.
> 
> 1) An older kicad should load a data file that is has never seen before.

Is this fools' gold? A PDF reader from 2005 would probably still load a
PDF made by newer software, even if there are new features it cannot
understand. It might say "You can't see the embedded 4D MegaContent
(TM), upgrade to a version that support PDF spec v5.6 for that", but
it will show you what it can. You'd be annoyed if it didn't, it would be
like Flash needing the latest version to watch your video, without the
excuse that is necessary to implement the latest and greatest DRM fad.

> The motivation should be that you want the flexibility to solve a specific problem.

The motivation is that I want the flexibility to add a field to a
.kicad_mod file, that still allows someone else to read the footprint,
if they don't *need* to know about that field. Currently, that will
cause THROW_PARSE_ERROR(), and they get nothing.

> But it should not name future proofing as the motivation, because you don't want to
> upgrade.  That's the part that gives me conceptual grief.

It's not because *I* don't want to upgrade, *I'm* to the one who's
hypothetically extended some aspect of the footprint format for my own
ends. It's because J. Random McTrunkBuild (or even his cousin,
McDistroVersion) shouldn't need to recompile with a patch from me to
read a footprint of mine which has my field "(user_sku 45443)" or
"(jedec_ref "SOT45")" in it, when he doesn't need or care about that
field.

The current state is there no way for people (not intimately familiar
with the .kicad_mod format) downloading a footprint now to know if it's
compatible with their KiCad without loading the footprint and then
guessing that the "Expected...." message means the footprint contains
unknown fields, as opposed to being malformed.

Forced recompiles are only free if your time is worthless and any
problems caused by running bleeding-edge PCB software in production
environments have zero cost.