Re: gEDA-user: Using mm units in .pcb files

[DJ Delorie <dj@xxxxxxxxxxx>]

> Now, of course, old lex/yacc hands will point out that this kind of 
> communication is dangerous, since the parser looks ahead,

The parser looks ahead to scan tokens, which means you need to
recognize all the tokens in the parser, not half in the parser and
half in the lexer.  It will reduce rules in order, though.  So you'd
have to parse the units command and store the value in the footprint
you're working on (not a global) so that further parsing of that
footprint has its default.  You'd have to do the units scaling in the
parser also.

> (*) Or, instead of adding keywords, you could say that a rule on one
> of the numbers in the "element" line, say the mark, was the default
> for the footprint.  But that seems excessively obscure.

One of my tools does that - "no units" means "use previously seen
units", from whatever you used last.  So you could use "mm" on the
first coordinate of an ElementLine and skip it on the rest of the
line.


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