[Jprogramming] is result of 15!:14 permanent?

[Elijah Stone]

Its address will not change.  It will stick around until it is explicitly 
freed (it could be freed by you with memf or by a c library with free).  I had 
vague plans to implement something that could be freed automatically, but have 
not done so yet.  However, depending on usage, you could pass in a j array 
instead (character array with the appropriate length), which would avoid the 
need to free manually.

On Tue, 18 Jul 2023, Igor Zhuravlov wrote:

> To prepare some structure as argument to DLL call, a memory should be 
> allocated by mema before call, and freed by memf after use. So that 
> structure's life cycle is under the manual control.
>
> I want to delegate this care to JE, something like this:
>
>  struct=. SIZEOF # ' '     NB. equiv. to:
>  addr=. 15!:14 < 'struct'  NB.   struct=. mema SIZEOF
>  NB. fill the struct...
>  SIGNATURE 15!:0 < < addr  NB. call DLL with addr as a sole parameter
>  return.                   NB. let JE to do (memf addr) implicitly
>
> But the question here is: does JE keep the result of (15!:14 < 'struct') 
> permanent? Or situations are possible when a noun's data address can change 
> (GC, unaliasing etc)?
>
> -- 
> Regards,
> Igor
>
>
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