Re: hash-table-{to, from}-alist

[Andreas Schwab <schwab@suse.de>]

Ted Zlatanov <tzz@lifelogs.com> writes:

> I ended up with this code to put a list into Fmake_hash_table format
> ('params' is a Lisp_Object that holds a bunch of conses).
>
> 	      int param_count = 0;
> 	      Lisp_Object *pa = (Lisp_Object*) xmalloc(XFASTINT(Flength(params)) * sizeof(Lisp_Object));
>
> 	      while (!NILP(params))
> 		{
> 		  pa[param_count++] = CAR_SAFE(params);
> 		  params = CDR_SAFE(params);
> 		}
>
> 	      Lisp_Object ht = Fmake_hash_table(param_count, pa);

This is of course a memory leak, since pa is never freed.

> I would prefer it if I could avoid all that work, but it seems (from
> reading lisp.h and hunting for similar code) that it must be done as
> above.  I don't see a macro to convert a Lisp_Object that holds a list
> into the Lisp_Object* that a lot of functions need.

Since you know the max size of the array, just declare it as such.

(One more reason to implement it in Lisp.)

Andreas.

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Andreas Schwab, SuSE Labs, schwab@suse.de
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