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Subject: Re: [geda-user] FOSDEM
From: John Doty <jpd AT noqsi DOT com>
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Date: Sun, 8 Feb 2015 08:30:33 -0700
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On Feb 8, 2015, at 4:22 AM, Chris Smith <space DOT dandy AT icloud DOT com> wrote:

> 
>> On 7 Feb 2015, at 21:19, John Doty <jpd AT noqsi DOT com> wrote:
>>> On Feb 7, 2015, at 1:44 PM, Chris Smith <space DOT dandy AT icloud DOT com> wrote:
>>> 
>>> It's just a text file and AWK and sed are text processors.
>> 
>> Except that they are line oriented. Things like AWK and cut are field oriented at the next level. What are your record and field punctuation? How would you do the following in your system?
>> 
>> awk '/^C /{print $7}' Interface.*.sch | sort | uniq
> 
> This is what a simple schematic might look like as a valid Lua construct. I've deliberately formatted it to look as close to the gEDA format as possible:
> schematic = { {
> 'v', 20110115, 2 },{
> 'C', 40000, 40000, 0, 0, 0, 'title-B.sym' },{
> 'C', 46000, 48700, 1, 0, 0, 'vcc-1.sym' },{
> 'C', 46100, 46000, 1, 0, 0, 'gnd-1.sym' },{
> 'C', 46300, 47600, 1, 90, 0, 'resistor-2.sym',
> {
> 'T', 45950, 48000, 5, 10, 0, 0, 90, 0, 1,
> device='RESISTOR' },{
> 'T', 46000, 48300, 5, 10, 1, 1, 180, 0, 1,
> refdes='R1' },{
> 'T', 45700, 47800, 5, 10, 1, 1, 0, 0, 1,
> value='10k' }
> }, {
> 'C', 46300, 46500, 1, 90, 0, 'resistor-2.sym',
> {
> 'T', 45950, 46900, 5, 10, 0, 0, 90, 0, 1,
> device='RESISTOR' },{
> 'T', 46000, 47200, 5, 10, 1, 1, 180, 0, 1,
> refdes='R2' },{
> 'T', 45700, 46700, 5, 10, 1, 1, 0, 0, 1,
> value='20k' }
> }, {
> 'N', 46200, 48500, 46200, 48700, 4 },{
> 'N', 46200, 47600, 46200, 47400, 4 },{
> 'N', 46200, 46500, 46200, 46300, 4 }
> }
> Chris
> 

Shudder. Here anybody who’s processing this in a textutilish way needs to write a whole bunch of extra stuff to remove all of the unneeded punctuation. “5” is a perfectly good number, but “5,” isn’t. 

This also demonstrates the sort of misconception that can creep in with this approach. “device=‘resistor’” is wrong: to the parser, text is text. Whether the “=“ is to be interpreted depends on what you are doing. In text sometimes there’s no “=“, sometimes more than one. Often, “=" punctuates an attribute, but sometimes it’s just part of a note to the reader. Not the parser’s call.

The file format should be language-neutral. We have that now. If it ain’t broke, don’t fix it. If Lua is as good as you claim, you could have written a parser for the existing format in the time we’ve wasted here. What problem does changing the file format solve?

John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd AT noqsi DOT com