[PD-dev] how to look up whether a symbol already exists?

[Hans-Christoph Steiner]

On Nov 24, 2007, at 4:32 AM, zmoelnig at iem.at wrote:

> Quoting Hans-Christoph Steiner <hans at eds.org>:
>
>>
>> Is there anyway to check whether a symbol already exists?
>
> i don't know of any.
>
>
> 2 suggestions:
> a) a symbol is a pointer
> if you get a symbol as "t_symbol*s" and s!=NULL, then you can safely
> assume that the symbol already exists (except someone evil sent you
> garbage)
> so you can implement:
> int symbol_exists(t_symbol*s) { return (0!=s); }
>
> b) you can always make sure, that a certain string is always
> represented as a symbol; which guarantees that your symbol exists.
> int symbol_exists(char*string) { gensym(string); return 1; }
>
>
> in practice, i think both implementations are rather a joke.
> what do you need this for?
>
>
> finally, you can bind a "class" to a symbol and lookup the class by  
> it's name.

I was thinking if using this to check whether a libdir had loaded its  
associated DLL so it wouldn't be opened multiple times with dlopen 
().  But I think dlopen() has an associated technique to check, so  
I'll try that.

.hc


>
>
> fma.dsr
> IOhannes
>
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