Macro

Summary

Defines a FLI union type corresponding to the C union type.

Package

fli

Signature

define-c-union name-and-options &rest slot-descriptions => list

name-and-options ::= name | (name option*)

option::= (:foreign-name string) | (:forward-reference-p forward-reference-p)

slot-descriptions ::= {slot-name | (slot-name slot-type)}*

Arguments

name

A symbol naming the new union type descriptor

string

A string specifying the foreign name of the type

forward-reference-p

A boolean.

slot-descriptions

A sequence of symbols, possibly with type descriptions, naming the slots of the union.

slot-name

A symbol naming the slot.

slot-type

The FLI type of the slot.

Values

list

The list (:union name).

Description

The macro define-c-union is used to define a FLI union type specifier, which corresponds to the C union type. It is a convenience function, as a union type could also be defined using define-foreign-type.

A union is an aggregate type, or collection, of other FLI types. The types contained in a union are referred to as slots, and can be accessed using the foreign-slot-type and foreign-slot-value functions.

When forward-reference-p is true, the new type specifier is defined as a forward reference type and descriptions can be empty. See define-foreign-forward-reference-type.

Example

In the following example a union is defined using define-c-union, and the corresponding C code is given.

(fli:define-c-union a-point (x :int)

                            (color :byte)

                            (ident :char))

union a-point {

  int x;

  byte color;

  char ident;

};

See also

define-c-enum
define-c-struct
define-c-typedef
define-foreign-type
FLI Types