# form_hook 3x 2024-01-05 ncurses 6.4 Library calls

    form_hook(3x)                    Library calls                   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.

### 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).

### 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).

### 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).

### 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(3)).

## 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.

## SEE ALSO

           curses(3x), form(3x)

    ncurses 6.4                       2024-01-05                     form_hook(3x)