InterfaceableObject

struct iobj_t

This type has only template character.  It defines the general structure of an interfaceable object.  Such an object consists of a pointer to the object data and another pointer to the function table implementing the interface.  The object is accessed only through the interface.

Usage

Use iobj_DECLARE to declare your own interfaceable object type.  Use genericcast_iobj to a type into its standard type.

Example

Consider an interfaceable object example_t with its interface example_it.

struct example_it {
   int (*fct1) (struct example_t * obj, ...) ;
   int (*fct2) (struct example_t * obj, ...) ;
} ;

struct example_t {
   struct example_t *  object ;
   struct example_it * iimpl ;
} ;

The interfaceable object example_t can be declared with

iobj_DECLARE(example_t, example) ;

An anonymous type which is compatible with example_t can be declared with:

struct mystructure_t {
   iobj_DECLARE(, example) iexample ;
} ;
// this declares the structure
struct mystructure_t {
   struct { struct example_t * object ; struct example_it * iimpl } iexample ;
} ;

The anonymous type is useful to prevent header inclusion and makes compilation faster.  To cast such an anonymous type to the standard type use

struct mystructure_t my ;
struct example_t * iexample = genericcast_iobj(&my.iexample, example) ;

The macro genericcast_iobj checks that my.iexample is compatible with example_t.