define-c-union 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 foreign-name) | (:forward-reference-p forward-reference-p)

slot-descriptions ::= {slot-description}*

slot-description ::= (slot-name slot-type)

Arguments

Values

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.

The FLI type specifier is named by name, with optional foreign name foreign-name.

Each slot-description is a list of a symbol slot-name and a corresponding FLI type descriptor slot-type which is the type of the slot named by slot-name.

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.

Notes

foreign-name, specifying the foreign name, is supported only for documentation purposes.

Examples

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
2 FLI Types