[PD] definitions of data types

Mathieu Bouchard matju at artengine.ca
Fri Feb 10 23:09:06 CET 2006

On Mon, 6 Feb 2006, Frank Barknecht wrote:

> I just wanted to avoid calling it "symbol", which of course would be the
> proper term, but is very confusing when you want to differentiate it
> from the symbol-symbol (Hi, Alice!.) Using "word" is used as a casual
> term here, intended to be understood by artists, not computing
> scientists. ;)

Even among comp.sci. and programmers, "word" doesn't have a consistent
definition. Some define it as a 16-bit integer, some define it as an
integer the same size as the main registers of a computer, and then which
ones are the "main" ones is debatable. That's just one usage of the "word"  
word! Then there is Forth, in which "word" means like "atom" in Pd. In
parser theory it may mean "single letter" (i'm not joking!).

> Yes, you can [pack] pointers just fine. Btw: "Pack" could be an
> alternative name for a list-message.

That sounds like a good idea worthy of investigation.

> [route] and [select] only deal with the other types of messages,
> however there is a [trigger pointer] and [t a] also passes along a
> pointer.

Yes. For all practical purposes, there are three stable atom types, and 
then a bunch of extras. In the not-too-periodic table of the atom types,

stable:         A_FLOAT    A_SYMBOL A_POINTER |
virtual:     A_DEFFLOAT A_DEFSYMBOL           |
radioactive:   A_DOLLAR   A_DOLLSYM           | A_COMMA A_SEMI

In which "stable" and "radioactive" are the only ones actually existing, 
and the others are cases of trying to shove too many features in 

> I see data types in Pd slightly different. Defining data types would
> also need to take GemLists or PDP-packets into account.

Those are message-types, and GF's "grid" is also a message-type, but 
it's partially because pd doesn't support user-defined atom-types, so 
defining those things as message-types is a way around the problem.

 _ _ __ ___ _____ ________ _____________ _____________________ ...
| Mathieu Bouchard - tél:+1.514.383.3801 - http://artengine.ca/matju
| Freelance Digital Arts Engineer, Montréal QC Canada

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