Struct and Union Clauses#

“Struct clauses” and “union clauses” (referred to collectively as “container clauses”) are used to specify naming in inclusion of class slots in exactly the same way that the options in the file clause control the handling of global definitions. Like the function clauses described above, they consist of the reserved word struct or union, a string which gives the full C name of the container declaration, an optional renaming, and a list of options. If we have a structure defined by

typedef struct cons {
   int index;
   struct object *head;
   struct cons *tail;
} cons_cell;

we could use the following interface definition:

define interface
   #include "cons.h";
   struct "struct cons" => <c-list>,
      superclasses: {<sequence>},
      prefix: "c-list-",
      name-mapper: identity-name-mapping;
end interface;

Valid options for container clauses include: import:, prefix:, rename:, seal-functions:, inline-functions:, read-only:, equate:, and map:. These options act like the equivalent options which may be specified in a file clause, but they apply to the slots of a single “class” rather than to globally defined objects. Options specified within a container clause override any global defaults that might have been specified in the #include clause. Container clauses also permit the superclasses: option described in Specifying class inheritance.

When a pointer type needs to be created for a struct, this can be done with the pointer-type-name: option in the struct clause:

define interface
   #include "event.h";
   struct "struct event",
      pointer-type-name: <event*>;
end interface;


This will not currently change the name of generated pointer types due to using a pointer type in the header file. It will only add a pointer-type-name: option to the generated C-struct or C-union definition.

Although the recommended method for specifying a container type is to use the full C name (i.e. struct foo), you may also use an alias defined by a typedef. Thus, in the above example, you could have specified either struct cons or cons_cell, with identical results.