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

       ncurses(3NCURSES), form(3FORM).

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.

                                                                                                     hook(3FORM)