form_hook - set hooks for automatic invocation by applications

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

       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).

form_hook - set hooks for automatic invocation by applications

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

       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)).

ncurses(3NCURSES), form(3FORM)

ncurses 6.5                                        2024-12-28                                        hook(3FORM)

#include<form.h>intset_field_init(FORM*form,Form_Hookfunc);Form_Hookfield_init(constFORM*form);intset_field_term(FORM*form,Form_Hookfunc);Form_Hookfield_term(constFORM*form);intset_form_init(FORM*form,Form_Hookfunc);Form_Hookform_init(constFORM*form);intset_form_term(FORM*form,Form_Hookfunc);Form_Hookform_term(constFORM*form);