[DGD] LPC_mapping in kfun extension

[Raymond Jennings]

Is there a way to create multiple scratch values?

On Tue, Aug 1, 2017 at 1:24 AM, Felix A. Croes <felix at dworkin.nl> wrote:

> "nikoroleva ." <natasha.i.koroleva at gmail.com> wrote:
>
> > I have created this kfun extension to return a mapping and in the
> > returned mapping the key is the value. Is it my mistake?
> >
> > https://gist.github.com/november-kilo/27d9f2308d6ce8a05e446db82c0ff94c
> >
> > LPC_dataspace data;
> > LPC_mapping mapping;
> > LPC_value mapping_key, mapping_value;
> > LPC_string key_str, val_str;
> > char key[100];
> > char val[5];
> > data = lpc_frame_dataspace(f);
> > mapping_key = lpc_value_temp(data);
> > mapping_value = lpc_value_temp(data);
> > sprintf(key, "key_%d", 1);
> > sprintf(val, "val_%d", rand());
> > key_str = lpc_string_new(data, key, strlen(key));
> > val_str = lpc_string_new(data, val, strlen(val));
> > lpc_string_putval(mapping_key, key_str);
> > lpc_string_putval(mapping_value, val_str);
> > mapping = lpc_mapping_new(data);
> > lpc_mapping_assign(data, mapping, mapping_key, mapping_value);
> > lpc_mapping_putval(retval, mapping);
>
>
> Interesting.  What goes wrong here is that lpc_value_temp() does not
> generate a new scratch value, but reuses the same one every time.
> Obviously, to create a mapping key/value pair you need at least two
> distinct scratch values, something which I overlooked.
>
> Actually, you do have another value available, the return value.  So
> the following should work: replace
>
>     mapping_value = lpc_value_temp(data);
>
> with
>
>     mapping_value = return_value;
>
> That will keep you going for now, until you reach the point where you
> need 3 distinct values. :)
>
> Regards,
> Felix Croes
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