[PD-dev] can externals create data structures/templates?

[Dan Wilcox]

I'd be nice to include this info in source comments somewhere... :)

> On Aug 5, 2019, at 10:44 PM, pd-dev-request at lists.iem.at wrote:
> 
> Date: Mon, 5 Aug 2019 22:39:26 +0200
> From: "Christof Ressi" <christof.ressi at gmx.at <mailto:christof.ressi at gmx.at>>
> To: "x nor" <x37v.alex at gmail.com <mailto:x37v.alex at gmail.com>>, pd-dev <pd-dev at lists.iem.at <mailto:pd-dev at lists.iem.at>>
> Subject: Re: [PD-dev] can externals create data structures/templates?
> Message-ID:
> 	<trinity-77b48c6e-2e1c-4b37-9700-523e7c7d675d-1565037566616 at 3c-app-gmx-bs18>
> 	
> Content-Type: text/plain; charset=UTF-8
> 
>> is there documentation for what binbufs are and how they're used?
>  
> I think you just have to read the source code in m_binbuf.c. But here's a general guide:
>  
> Binbufs are containers for atoms. Unlike Pd lists, it can contain "special" atoms like A_SEMI or A_DOLLSYM.
>  
> binbuf_text() converts a C string to a list of atoms.
> bufbuf_gettext() converts the atoms back to a C string.
>  
> binbuf_add() simply adds any kind of atoms to the binbuf
> binbuf_getnatom() returns the size
> binbuf_getvec() returns a pointer to the atoms.
>  
> binbuf_addbinbuf() adds the content of another binbuf (possible containing "special" atoms) but bashes everything to A_FLOAT and A_SYMBOL
> binbuf_restore() adds a list of atoms but restores "special" atoms from symbols, e.g. ";" -> A_SEMI, "\\$0-foo" -> A_DOLLSYM, etc.
>  
> binbuf_eval() evaluates the stored binbuf by sending it as a message to the given target.
> You can also pass an atom list as arguments, e.g. for a dollar symbols like "$1-foo".
> "$0" is always substituted with the dollar zero of the current canvas (see canvas_getdollarzero, canvas_getcurrent and canvas_setcurrent).
> Note that a A_SEMI atom will denote the start of a new message and the following atom will be taken as the new message target (must be a symbol).
>  
> Here's an example (taken from x_text.c):
> 
> a) The patch file:
> 
> static char text_templatefile[] = "\
> canvas 0 0 458 153 10;\n\
> #X obj 43 31 struct text float x float y text t;\n\
> ";
> 
> b) create a binbuf
> 
> binbuf_text(b, text_templatefile, strlen(text_templatefile));
> 
> c) evaluate
> 
> binbuf_eval(b, &pd_canvasmaker, 0, 0);
> 
> Here's what happens:
> 
> 1) "canvas 0 0 458 153 10;" goes to canvas maker -> create a new canvas, push it on the loading stack and bind #X to the canvas.
> 2) the ";" terminates the messages and begins a new one. "#X" (= our canvas) will be the new target.
> 3) "obj 43 31 struct text float x float y text t;" asks the canvas to create an object (like in dynamic patching)
> 4) vmess(s__X.s_thing, gensym("pop"), "i", 0) sends the "pop" messages to the canvas. This effectively pops the canvas from the stack and #X is restored to whatever it has been bound before.
>  
> Hope that helps.
>  
> Christof

--------
Dan Wilcox
@danomatika <http://twitter.com/danomatika>
danomatika.com <http://danomatika.com/>
robotcowboy.com <http://robotcowboy.com/>



-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.puredata.info/pipermail/pd-dev/attachments/20190806/e4f9cde1/attachment-0001.html>