Chapter 10

Supporting Named Parameters

One way in which XS modules and Inline::C modules are essentially the same is 

that they both benefit from careful interface design. In terms of Gnome::MIME, 

this means supporting a named parameter style interface to file_type():

$type = Gnome::MIME::file_type(filename     => $filename,

                               default_type => "text/html",

                               read_file    => 1);

The full inlined function implementing this interface is shown in Listing 10 3.

Listing 10 3. Inline Function with Named Parameter Support

char * file_type (SV *dummy, ...) {

  Inline_Stack_Vars;         // get access to the Inline stack macros

  char *filename     = NULL; // variables for named params values

  char *default_type = NULL;

  IV    read_file    = 0;

  int x;                     // loop counter

  // loop over args by pairs and fill in parameters

  for (x = 0; x < Inline_Stack_Items; x+=2) {

    char *key = SvPV(Inline_Stack_Item(x), PL_na);

    if (strEQ(key, "filename")) {

      filename = SvPV(Inline_Stack_Item(x+1), PL_na);

    } else if (strEQ(key, "default_type")) {

      default_type = SvPV(Inline_Stack_Item(x+1), PL_na);

    } else if (strEQ(key, "read_file")) {

      read_file = SvIV(Inline_Stack_Item(x+1));

    } else {

      croak("Unknown key found in Gnome::MIME::file_type parameter list: %s",

            key);

    }

  }

  // make sure we have a filename parameter

  if (filename == NULL) croak("Missing required parameter filename.");

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