Interfaces

Data Structures
struct	ObjIface

Macros
#define	objIfTmplName(iface)   iface##_tmpl
#define	objIfImport(iface)   extern iface objIfTmplName(iface)
#define	objIfCheck(iface)
#define	objIfBase(iface)    ((ObjIface*)((iface)->_implements, (iface)->_parent, (iface)->_size, (iface)))

Typedefs
typedef struct ObjIface	ObjIface

Detailed Description

Interfaces define contracts that classes implement. An interface is a list of function pointers representing methods that fulfill a specific contract. Interfaces support inheritance, allowing child interfaces to extend parent interfaces.

The ObjIface structure serves dual purposes depending on context:

Template Form - The publicly declared master copy of an interface:

• Contains basic metadata: parent interface and structure size
• All method pointers are NULL
• The template's memory address uniquely identifies the interface
• Used as a key to query classes for interface implementations
• When queried, the system returns a populated copy with method pointers filled in

Implementation Form - A statically scoped instance used during class definition:

• Contains a pointer to the interface template being implemented
• Contains function pointers to the actual implementation methods
• Used to register an implementation with a specific class
• Multiple classes can provide different implementations of the same interface

Example from a .cxh file:

interface Printable {
    void print();
    void println();
}
 
class Document implements Printable {
    string content;
}

This generates a template Printable_tmpl and implementation structures automatically.

Macro Definition Documentation

objIfBase

#define objIfBase

(

iface

)

((ObjIface*)((iface)->_implements, (iface)->_parent, (iface)->_size, (iface)))

ObjIface *objIfBase(InterfaceType *iface)

Cast an interface pointer to base ObjIface type

Parameters

iface

Pointer to any interface structure

Returns

Base ObjIface pointer (performs validation through comma operator)

Definition at line 94 of file objiface.h.

objIfCheck

#define objIfCheck

(

iface

)

Value:

    static_assert(((iface)->_implements,                                        \
                   (iface)->_size,                                              \
                   offsetof(*(iface), _parent) == offsetof(ObjIface, _parent)), \
                  "Not an interface")

void objIfCheck(InterfaceType *iface)

Compile-time check that a pointer is to a valid interface structure

Parameters

iface

Pointer to interface structure to validate

Definition at line 82 of file objiface.h.

objIfImport

#define objIfImport

(

iface

)

extern iface objIfTmplName(iface)

Import an external interface template declaration

Parameters

iface

Interface type name

Returns

Expands to extern declaration for the interface template

Definition at line 75 of file objiface.h.

objIfTmplName

#define objIfTmplName

(

iface

)

iface##_tmpl

Construct interface template name from interface type name

Parameters

iface

Interface type name (e.g., Printable)

Returns

Expands to the template variable name (e.g., Printable_tmpl)

Definition at line 69 of file objiface.h.

Typedef Documentation

ObjIface

typedef struct ObjIface ObjIface

Core interface structure

This structure has different interpretations based on context. See the Interfaces overview for detailed explanation of template vs implementation forms.

Definition at line 48 of file objiface.h.