[PD] default value for an abstraction's creation argument

Mathieu Bouchard matju at artengine.ca
Mon Jul 23 07:36:56 CEST 2007

On Mon, 23 Jul 2007, Frank Barknecht wrote:

> Almost as elegant as possible with current Pd: Arguments, that you
> don't specify, get initialized as 0.

That's not strictly true: if a dollsym gets expanded using nonexistent 
arguments, those parts do not get replaced.

A_DOLLAR atoms are atoms that are just $0 $1 $2 $3... without anything to 
the left or right (nonbackslashed commas-or-semicolons count as 
delimiters). Expanding an A_DOLLAR gives exactly what the argument passed 
was. In that context, nonexistent arguments become zeroes.

A_DOLLSYM atoms are atoms that are mixed symbol parts and dollar parts. 
Before 0.40 this instead was only one dollar part followed by one symbol 
part. In that context, nonexistent arguments stay exactly like they are. 
(Instead I would've guessed empty symbols, but Pd isn't that consistent 
when it comes to dummy symbols)

BTW, this can lead you to a way to figure out for sure whether a certain 
argument was supplied or not, by checking the discrepancy between A_DOLLAR 
and A_DOLLSYM, but that's quite twisted.

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| Mathieu Bouchard - tél:+1.514.383.3801, Montréal QC Canada

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