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form_hook 3x 2024-03-16 ncurses 6.5 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_term

       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.