Swig problem

ruby-talk
1

I am trying to wrap a function that either takes a char * or NULL
How would I wrap this in swig?

The c version accepts a conts char * or NULL

librdf_node* librdf_new_node_from_blank_identifier(librdf_world *world,
const char * identifier);

I do a typemap as follows

I tried this but am still getting a TypeError converting Nil to String

%typemap(ruby,in) const char *identifier {
if $input == Qnil{
$1 == NULL;
else
$1 = STR2CSTR($input);
}
}

2

dominic sisneros wrote:

I do a typemap as follows

I tried this but am still getting a TypeError converting Nil to String

%typemap(ruby,in) const char *identifier {
if $input == Qnil{
$1 == NULL;
else
$1 = STR2CSTR($input);
}
}

Rerun swig and recompile your extension before trying again :wink:

I can see you didn’t because there are 2 syntax errors (and 1 semantic
error) in your typemap. Your compiler would have caught the 2 syntax
ones. Or maybe you just didn’t notice the error messages.

  • C requires that you parenthesize the test expression after the “if”
  • Your “else” has no previous “if” (removing the inner braces will help)
  • “$1 == NULL” doesn’t do anything.

Apart from these errors, your typemap is correct and your code will work
once you correct them.

Tobias