kicad-developers team mailing list archive

[Adam Wolf <adamwolf@xxxxxxxxxxxxxxxxxxxx>]

Cirilo,

I like that.

Adam Wolf
On Jan 13, 2015 2:45 PM, "Cirilo Bernardo" <cirilo.bernardo@xxxxxxxxx>
wrote:

>
> On Wed, Jan 14, 2015 at 5:20 AM, Tomasz Wlostowski <
> tomasz.wlostowski@xxxxxxx> wrote:
>
>> Hi all,
>>
>> During my work on diff pairs/matched length tools, I've encountered a
>> rather tricky problem: as the diff pair gap specific to a particular
>> pair of traces is stored nowhere, the shove algorithm will mess up DP
>> coupling after saving and re-loading the board. Ergo: the DP gaps (and
>> possibly other settings) need to be stored somewhere in .kicad_pcb
>> files. Perhaps in a yet another s-expr token.
>>
>> The problem is that adding any new token to the file format causes all
>> precedent versions of pcbnew to drop an error attempting to load the
>> file. I would propose two solutions to overcome this:
>> - (a dumb one) if the version in the file header is newer than the
>> version supported by the running application, issue warnings instead of
>> fatal errors on unknown tokens,
>> - (a bit smarter) enclose all optional tokens in a "minimum" version
>> block ( min_version version_number ( optional_token ( ... ) ) ) that
>> would be ignored if the application version < version_number.
>>
>> I consider this modification quite important from the point of view of
>> adding future features and the upcoming stable version: if we keep
>> things as they are, adding any new feature will either make the files
>> unreadable to the stable version or force us to support saving in
>> multiple format versions.
>>
>> Looking forward to your feedback,
>> Tom
>>
>
> I would prefer to do what had been done in the past - simply increase
> the File Version number and don't expect earlier versions to support
> the new features (or to read the board at all).  What we *can* safely
> do is check the file version number when parsing and if the parser
> does not recognize it then we can display a message to say that it
> is a newer file version and we cannot read it. If people are collaborating
> and this can be an issue then they must agree on a version of KiCad
> to use; after all in most cases they can build any historical version
> from the past 2 years.
>
> - Cirilo
>
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