form_hook(3X)

NAME
form_hook - set hooks for automatic invocation by applications

SYNOPSIS
#include <form.h>
int set_field_init(FORM *form, Form_Hook func);
Form_Hook field_init(const FORM *form);
int set_field_term(FORM *form, Form_Hook func);
Form_Hook field_term(const FORM *form);
int set_form_init(FORM *form, Form_Hook func);
Form_Hook form_init(const FORM *form);
int set_form_term(FORM *form, Form_Hook func);
Form_Hook form_term(const FORM *form);

DESCRIPTION
These functions make it possible to set hook functions to be called at various points in the automatic processing of input event codes by form_driver.

The function set_field_init sets a hook to be called at form-post time and each time the selected field changes (after the change). field_init returns the current field init hook, if any (NULL if there is no such hook).

The function set_field_term sets a hook to be called at form-unpost time and each time the selected field changes (before the change). field_term returns the current field term hook, if any (NULL if there is no such hook).

The function set_form_init sets a hook to be called at form-post time and just after a page change once it is posted. form_init returns the current form init hook, if any (NULL if there is no such hook).

The function set_form_term sets a hook to be called at form-unpost time and just before a page change once it is posted. form_init returns the current form term hook, if any (NULL if there is no such hook).

RETURN VALUE
Routines that return pointers return NULL on error. Other routines return one of the following:

E_OK
    The routine succeeded.

E_SYSTEM_ERROR
    System error occurred (see errno).

SEE ALSO
curses(3X), form(3X).

NOTES
The header file <form.h> automatically includes the header file <curses.h>.

PORTABILITY
These routines emulate the System V forms library. They were not supported on Version 7 or BSD versions.

AUTHORS
Juergen Pfeifer. Manual pages and adaptation for new curses by Eric S. Raymond.