Re: [PD-dev] How to free memory of t_symbol
Em qui., 22 de fev. de 2024 às 11:26, Christof Ressi escreveu: > You must never attempt to free a symbol! > poor symbols, trapped forever ___ Pd-dev mailing list Pd-dev@lists.iem.at https://lists.puredata.info/listinfo/pd-dev
Re: [PD-dev] How to free memory of t_symbol
Thanks :-D
BTW, Symbols in sclang work the same way. Also, they are frequently used
in scripting languages. In this context, this is also referred to as
"string interning", see https://en.wikipedia.org/wiki/String_interning
Christof
On 22.02.2024 15:38, Pierre Alexandre Tremblay wrote:
This is by far the best explanation of symbols I’ve read, ever.
Thanks!
On 22 Feb 2024, at 13:41, Christof Ressi wrote:
Hi,
Pd symbols are immutable and permanent. `gensym("foo")` looks if the symbol
"foo" already exists; if yes, it just returns it, otherwise it creates a new symbol, adds
it to the global symbol table and finally returns it.
You must never attempt to free a symbol!
```
t_symbol **x_weights_arrays;
t_symbol *x_biases_array;
```
Here you must only free `x_weights_array`, which is an array of `t_symbol*`,
but not the `t_symbol*` elements themselves.
---
Side note: since symbols are unique and persistent, they can be compared *by
address*. In other words, two symbols are equal if they have the same address.
This is different from ordinary C-strings which may reside at different memory
locations and thus need to be compared with `strcmp()` (or equivalent
functions).
Christof
On 22.02.2024 10:19, Alexandros Drymonitis wrote:
I have a data structure with a symbol and an array of symbols that store array
names defined as:
```
t_symbol **x_weights_arrays;
t_symbol *x_biases_array;
```
When I'm done with them, I want to free the memory, but calling
free(x_biases_array) doesn't seem to work, and once called, as soon as I try to
do something else in Pd (like unlock the patch and choose an object), Pd
crashes.
I have narrowed down the error to freeing these symbols, and I'm sure the crash
is not caused by something else. I scanned m_pd.h to see if there is a function
to free t_symbol memory, but didn't seem to find anything. This might be
something obvious for C-savvy people, but I'm not one, so any advice is welcome.
___
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Re: [PD-dev] How to free memory of t_symbol
This is by far the best explanation of symbols I’ve read, ever.
Thanks!
> On 22 Feb 2024, at 13:41, Christof Ressi wrote:
>
> Hi,
>
> Pd symbols are immutable and permanent. `gensym("foo")` looks if the symbol
> "foo" already exists; if yes, it just returns it, otherwise it creates a new
> symbol, adds it to the global symbol table and finally returns it.
>
> You must never attempt to free a symbol!
>
>> ```
>> t_symbol **x_weights_arrays;
>> t_symbol *x_biases_array;
>> ```
> Here you must only free `x_weights_array`, which is an array of `t_symbol*`,
> but not the `t_symbol*` elements themselves.
>
> ---
>
> Side note: since symbols are unique and persistent, they can be compared *by
> address*. In other words, two symbols are equal if they have the same
> address. This is different from ordinary C-strings which may reside at
> different memory locations and thus need to be compared with `strcmp()` (or
> equivalent functions).
>
> Christof
>
> On 22.02.2024 10:19, Alexandros Drymonitis wrote:
>> I have a data structure with a symbol and an array of symbols that store
>> array names defined as:
>>
>> ```
>> t_symbol **x_weights_arrays;
>> t_symbol *x_biases_array;
>> ```
>>
>> When I'm done with them, I want to free the memory, but calling
>> free(x_biases_array) doesn't seem to work, and once called, as soon as I try
>> to do something else in Pd (like unlock the patch and choose an object), Pd
>> crashes.
>>
>> I have narrowed down the error to freeing these symbols, and I'm sure the
>> crash is not caused by something else. I scanned m_pd.h to see if there is a
>> function to free t_symbol memory, but didn't seem to find anything. This
>> might be something obvious for C-savvy people, but I'm not one, so any
>> advice is welcome.
>>
>>
>>
>>
>> ___
>> Pd-dev mailing list
>> Pd-dev@lists.iem.at
>> https://lists.puredata.info/listinfo/pd-dev
>
>
>
> ___
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Re: [PD-dev] How to free memory of t_symbol
Hi,
Pd symbols are immutable and permanent. `gensym("foo")` looks if the
symbol "foo" already exists; if yes, it just returns it, otherwise it
creates a new symbol, adds it to the global symbol table and finally
returns it.
You must never attempt to free a symbol!
```
t_symbol **x_weights_arrays;
t_symbol *x_biases_array;
```
Here you must only free `x_weights_array`, which is an array of
`t_symbol*`, but not the `t_symbol*` elements themselves.
---
Side note: since symbols are unique and persistent, they can be compared
*by address*. In other words, two symbols are equal if they have the
same address. This is different from ordinary C-strings which may reside
at different memory locations and thus need to be compared with
`strcmp()` (or equivalent functions).
Christof
On 22.02.2024 10:19, Alexandros Drymonitis wrote:
I have a data structure with a symbol and an array of symbols that
store array names defined as:
```
t_symbol **x_weights_arrays;
t_symbol *x_biases_array;
```
When I'm done with them, I want to free the memory, but calling
free(x_biases_array) doesn't seem to work, and once called, as soon as
I try to do something else in Pd (like unlock the patch and choose an
object), Pd crashes.
I have narrowed down the error to freeing these symbols, and I'm sure
the crash is not caused by something else. I scanned m_pd.h to see if
there is a function to free t_symbol memory, but didn't seem to find
anything. This might be something obvious for C-savvy people, but I'm
not one, so any advice is welcome.
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Re: [PD-dev] How to free memory of t_symbol
Am 22. Februar 2024 10:19:27 MEZ schrieb Alexandros Drymonitis : >I have a data structure with a symbol and an array of symbols that store array >names defined as: > >``` >t_symbol **x_weights_arrays; >t_symbol *x_biases_array; >``` > >When I'm done with them, I want to free the memory, but calling >free(x_biases_array) doesn't seem to work, and once called, as soon as I try >to do something else in Pd (like unlock the patch and choose an object), Pd >crashes. > Never free symbols. A symbol is created by `gensym` and owned by Pd. mfg.sfg.jfd IOhannes ___ Pd-dev mailing list Pd-dev@lists.iem.at https://lists.puredata.info/listinfo/pd-dev
Re: [PD-dev] How to free memory of t_symbol
On 2/22/24 14:45, Lucas Cordiviola wrote:
hi,
free(x_biases_array) doesn't seem to work
i'm not to good at C but you are missing the correct path
("nameofthestruct"->"nameofthevarible"). like
free(x->x_biases_array).
Yeah, that's a typo in the email, it's not in the code though. Thanks
for pointing it out.
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Re: [PD-dev] How to free memory of t_symbol
hi,
free(x_biases_array) doesn't seem to work
i'm not to good at C but you are missing the correct path
("nameofthestruct"->"nameofthevarible"). like
free(x->x_biases_array).
--
Mensaje telepatico asistido por maquinas.
On 22/02/2024 06:19, Alexandros Drymonitis wrote:
I have a data structure with a symbol and an array of symbols that
store array names defined as:
```
t_symbol **x_weights_arrays;
t_symbol *x_biases_array;
```
When I'm done with them, I want to free the memory, but calling
free(x_biases_array) doesn't seem to work, and once called, as soon as
I try to do something else in Pd (like unlock the patch and choose an
object), Pd crashes.
I have narrowed down the error to freeing these symbols, and I'm sure
the crash is not caused by something else. I scanned m_pd.h to see if
there is a function to free t_symbol memory, but didn't seem to find
anything. This might be something obvious for C-savvy people, but I'm
not one, so any advice is welcome.
___
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