Writing C Modules with XS

To get started, I would create two literal XSUBs:

MODULE = Gnome::MIME   PACKAGE = Gnome::MIME   PREFIX = gnome_mime_

GList *

gnome_mime_get_keys(type)

  const char * type

const char *

gnome_mime_get_value(type, key)

  const char * type

  const char * key

But this generates a compilation error:

Error:  GList *  not in typemap in MIME.xs, line 10

The last time you saw this error, it was for const char * and const gchar *, and 

the solution was to simply alias those types to the type used for char *. In this case, the 

solution won't be so easy there's no existing typemap with the behavior I'm 

looking for. In particular, I want a typemap that will take a GList* and return a ref 

erence to an AV*. You can find the completed typemap file in Listing 9 9.

Listing 9 9. typemap File with GList* Typemap

const char  *    T_PV

const gchar *    T_PV

GList *          T_GLIST

INPUT

T_GLIST

        croak("GList * input typemap unimplemented!");

OUTPUT

T_GLIST

        $arg = GList_to_AVref($var);

A typemap file has three sections. The first is a list of C type names and corre 

sponding typemap names. This allows a group of C types to share a single typemap. 

This section already has two lines in my typemap file:

const char  *    T_PV

const gchar *    T_PV

23

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