Re: gEDA-user: Functional blocks and PCB format changes

[gedau@xxxxxxxxxxxxx]

On Sat, Sep 04, 2010 at 01:16:01AM -0400, Rick Collins wrote:

<snip>

> But I suppose it is better to re-invent the wheel.  There is no reason to 
> try to foster any sort of compatibility in file formats between all the 
> different CAD tools.  There are always conversion programs to be written, 
> no?
>
> Rick 

Please note: I am not saying this for or against XML. I just felt like 
the above sentences implied using a specific file format is an ultimate 
solution for compatibility. Please always read "XML" as "any standard 
or widespread format, text or binary, for example json, plist, sql 
dumps, whatever".

Using xml as file format for PCB (or any CAD program) will not 
automatically make it compatible with any other CAD program. I see two 
different things here.

1. Use a file format that is well documented and known (this can be 
a standard format like XML, json, plist, or a custom format with proper 
documentation).
2. How the content is actually represented. 

Point 1. is a basis, a must. Without that, we can not talk about making 
two programs compatible, since the data can not be read or written by 
the other program. However, just being able to read the file, but not 
understanding what they mean, won't make any compatibility. Thus point 
2. is a must too.

XML may or may not be a good solution for 1., but doesn't do _anything_ 
to 2. The current file format is plain text and documented enough 
(in worst case by the source code) that any developer has the chance to 
parse or generate it, this it also fulfills the reqiurements in 1.

Switching (or not switching) to XML will not make a real difference 
in compatibility. Switching to any standard format may ease 
implementation as one doesn't need to write a custom parser. But don't 
overestimate this part either: using a parser generator helps a lot, 
and even going without that, I strongly believe that finally the real 
complex and big part of the work is 2., not 1. Making two CAD 
programs compatible is harder on the "how we represent the design 
internally" level than "how do we convert the representation to an 
actual file format".

Regards,

Tibor Palinkas






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