John -
There is more than one way to do it. :-)
First, you could simply use the OtherPars section, passing an SV*, and
modify the functions calling convention. For example, you can include a "my
$output" in your function call and get it out on the other side:
pp_def('some_func' =>
Pars => 'input_piddle(); [o] output_piddle()',
OtherPars => 'SV * output_scalar',
Code => q{
/* Code goes here; manipulate the output SV with Perl XS functions
*/
},
);
You would then call this function as
$output_piddle = $input_piddle->some_func(my $output_scalar);
The next option is to use the PMCode key. Beware, however, this does not
work with Inline::Pdlpp, only with compiled pd files. The PMCode section
specifies perl code that is meant to wrap the function you define. It looks
something like this:
pp_def('some_func' =>
Pars => 'input_piddle(); [o] output_piddle()',
OtherPars => 'SV * output_scalar',
Code => q{
/* Code goes here; manipulate the output SV with Perl XS functions
*/
},
PMCode => q{
sub some_func {
my ($input_piddle) = @_;
}
},
);
On Sat, Feb 9, 2013 at 11:54 AM, John Lapeyre <[email protected]>wrote:
> Hello,
>
> Does anyone know how to write a call to `pp_def' that somehow returns,
> or updates, scalar values ? I know that with `OtherPars' it is easy
> to specify that a scalar is to be passed as input. For output, do I
> have to somehow use the normal C api to perl to get at the contents of
> an SV?
>
> For instance, I might want to take piddles and or scalars as input and
> have scalars and possibly piddle as output. A clumsy solution is to
> pass a piddle of length 1, where I really want a scalar, in the `Code'
> string, and then write a wrapper function in perl to extract the
> scalar from the auxiallry piddle.
>
> A related question: With `GenericTypes' and the template mechanism
> `$T( ...', I can automatically generate interfaces for several
> types of piddles. Is it possible to somehow use this template with
> `OtherPars' ? In particular, I want to define a function via
> pp_def that takes a piddle and a scalar as arguments. I want the
> two arguments to be of the same type. For example, both integers,
> both doubles, etc.
>
> Thank you!
>
> John
>
>
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--
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." -- Brian Kernighan
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