Thanks for your insights Christof!
I would like to be able to access the data outside my external,
specifically with tabread4~.
I'm thinking I will create a canvas per data set, managed by my
object, that has all the tables I need, via the approach you gave me
some weeks ago (binbuf).
The private data structure approach is interesting but part of the
point is being able to utilize this data outside of the externals I
write, but either way it is good to know about that appraoch.
-Alex
On Tue, Jan 28, 2020 at 6:41 AM Christof Ressi <[email protected]
<mailto:[email protected]>> wrote:
Hi,
So my question is: if I allocate an array/table in an external,
do I have to manage its de-allocation or is there some sort of
reference counter?
A graphical array always belongs to a canvas and it will be
automatically be destroyed when the canvas is freed. Destroying a
single graphical array in code is a bit tricky and you need stuff
from private headers like g_canvas.h.
How about with canvases?
If I create a canvas per analysis data set, do I have to manage
the canvas de-allocation?
This is how you create a private canvas in the object constructor:
pd_vmess(&pd_canvasmaker,gensym("canvas"),"iiiii",0,0,100,100,10);
x_canvas =(t_canvas*)s__X.s_thing;
pd_vmess((t_pd *)x_canvas, gensym("pop"),"i",0);
Such a canvas will have an owner, but it doesn't actually belong
to a glist, so you have to free it yourself in the destructor:
pd_free((t_pd *)x_canvas);
Note that if you want to create a table outside the object
constructor, you should cache the current canvas with
canvas_getcurrent() in the constructor. Before creating a new
canvas you have to push the cached canvas with pd_push() or
canvas_setcurrent() and in the end pop it with pd_pop() or
canvas_unsetcurrent(). This makes sure that the canvas gets an
owner and doesn't go to the root canvas list.
If I de-allocate an array (inside a canvas I create in code or
not) and some other object is using that array, what happens?
A crash :-) Unless the object uses a gpointer, so it can check
whether the glist is still alive.
I just want to stress that managing canvasses/garrays
programmatically is not officially supported by the Pd API. It's
possible with the workarounds shown above, but I wouldn't
recommend it unless it's 100% necessary.
---
I'd like to be able to load several sets of tables with a single
object, and then access that data with an arbitrary number of
resynthizers.
You might reconsider whether you really need actual Pd tables to
do this. I think you only need them if the data should be
accessible as tables outside your own externals. Otherwise I would
strongly recommend to use your own private data structure and
share it among your externals.
Just create a faux-class like this:
static t_class *data_class;
typedef struct _data {
t_pd d_pd;
// your data..
} t_data;
// in the setup routine:
data_class=class_new(gensym("data private"),
0,0,sizeof(t_data),CLASS_PD,0);
There's no need to (de)allocate instances with pd_new()/pd_free(),
you can just do getbytes()/freebytes(), but you have to make sure
to set d_pd to data_class. See the "alist" class in x_list.c.
Because t_data is a Pd class, you can now safely bind instances to
symbols with pd_bind() and retrieve instances with pd_findbyclass().
As you can see, this allows you to easily share custom data
structures across externals. This is also safe as long as you
always access the data through the symbol with pd_findbyclass().
It will return NULL if the data has been unbound (and deleted).
This means you can have an object similar to [array define] which
creates a t_data instance and binds it to a symbol. In your patch
you can pass this symbol to your other externals which can
retrieve the data and do something with it.
Christof
On 27.01.2020 19:54, x nor wrote:
I'm working on an external that loads analysis data into tables
for use in re-synthesis and I want to make sure I'm not going to
be leaking memory with this approach.
I'd like to be able to load several sets of tables with a single
object, and then access that data with an arbitrary number of
resynthizers.
So my question is: if I allocate an array/table in an external,
do I have to manage its de-allocation or is there some sort of
reference counter?
How about with canvases?
If I create a canvas per analysis data set, do I have to manage
the canvas de-allocation? If I de-allocate an array (inside a
canvas I create in code or not) and some other object is using
that array, what happens?
Thanks,
Ale
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