<!--
  * t
  ****************************************************************************
  * Copyright 2018-2019,2020 Thomas E. Dickey                                *
  * Copyright 1998-2007,2010 Free Software Foundation, Inc.                  *
  *                                                                          *
  * Permission is hereby granted, free of charge, to any person obtaining a  *
  * copy of this software and associated documentation files (the            *
  * "Software"), to deal in the Software without restriction, including      *
  * without limitation the rights to use, copy, modify, merge, publish,      *
  * distribute, distribute with modifications, sublicense, and/or sell       *
  * copies of the Software, and to permit persons to whom the Software is    *
  * furnished to do so, subject to the following conditions:                 *
  *                                                                          *
  * The above copyright notice and this permission notice shall be included  *
  * in all copies or substantial portions of the Software.                   *
  *                                                                          *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  *
  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF               *
  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.   *
  * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,   *
  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    *
  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR    *
  * THE USE OR OTHER DEALINGS IN THE SOFTWARE.                               *
  *                                                                          *
  * Except as contained in this notice, the name(s) of the above copyright   *
  * holders shall not be used in advertising or otherwise to promote the     *
  * sale, use or other dealings in this Software without prior written       *
  * authorization.                                                           *
  ****************************************************************************
  * @Id: form_hook.3x,v 1.16 2020/10/18 00:06:29 tom Exp @
-->
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<HTML>
<HEAD>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="generator" content="Manpage converted by man2html - see https://invisible-island.net/scripts/readme.html#others_scripts">
<TITLE>form_hook 3x</TITLE>
<link rel="author" href="mailto:bug-ncurses@gnu.org">
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
</HEAD>
<BODY>
<H1 class="no-header">form_hook 3x</H1>
<PRE>
<STRONG><A HREF="form_hook.3x.html">form_hook(3x)</A></STRONG>                                                    <STRONG><A HREF="form_hook.3x.html">form_hook(3x)</A></STRONG>


</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
       <STRONG>form_hook</STRONG> - set hooks for automatic invocation by applications


</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
       <STRONG>#include</STRONG> <STRONG>&lt;form.h&gt;</STRONG>

       <STRONG>int</STRONG> <STRONG>set_field_init(FORM</STRONG> <STRONG>*</STRONG><EM>form</EM><STRONG>,</STRONG> <STRONG>Form_Hook</STRONG> <EM>func</EM><STRONG>);</STRONG>
       <STRONG>Form_Hook</STRONG> <STRONG>field_init(const</STRONG> <STRONG>FORM</STRONG> <STRONG>*</STRONG><EM>form</EM><STRONG>);</STRONG>

       <STRONG>int</STRONG> <STRONG>set_field_term(FORM</STRONG> <STRONG>*</STRONG><EM>form</EM><STRONG>,</STRONG> <STRONG>Form_Hook</STRONG> <EM>func</EM><STRONG>);</STRONG>
       <STRONG>Form_Hook</STRONG> <STRONG>field_term(const</STRONG> <STRONG>FORM</STRONG> <STRONG>*</STRONG><EM>form</EM><STRONG>);</STRONG>

       <STRONG>int</STRONG> <STRONG>set_form_init(FORM</STRONG> <STRONG>*</STRONG><EM>form</EM><STRONG>,</STRONG> <STRONG>Form_Hook</STRONG> <EM>func</EM><STRONG>);</STRONG>
       <STRONG>Form_Hook</STRONG> <STRONG>form_init(const</STRONG> <STRONG>FORM</STRONG> <STRONG>*</STRONG><EM>form</EM><STRONG>);</STRONG>

       <STRONG>int</STRONG> <STRONG>set_form_term(FORM</STRONG> <STRONG>*</STRONG><EM>form</EM><STRONG>,</STRONG> <STRONG>Form_Hook</STRONG> <EM>func</EM><STRONG>);</STRONG>
       <STRONG>Form_Hook</STRONG> <STRONG>form_term(const</STRONG> <STRONG>FORM</STRONG> <STRONG>*</STRONG><EM>form</EM><STRONG>);</STRONG>


</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
       These  functions make it possible to set hook functions to be called at
       various points in the automatic processing  of  input  event  codes  by
       <STRONG>form_driver</STRONG>.

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

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

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

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


</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
       Routines  that  return  pointers  return <STRONG>NULL</STRONG> on error.  Other routines
       return one of the following:

       <STRONG>E_OK</STRONG> The routine succeeded.

       <STRONG>E_SYSTEM_ERROR</STRONG>
            System error occurred (see <STRONG>errno(3)</STRONG>).


</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
       <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="form.3x.html">form(3x)</A></STRONG>.


</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
       The  header  file  <STRONG>&lt;form.h&gt;</STRONG>  automatically  includes  the  header  file
       <STRONG>&lt;curses.h&gt;</STRONG>.


</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
       These  routines  emulate  the  System  V  forms library.  They were not
       supported on Version 7 or BSD versions.


</PRE><H2><a name="h2-AUTHORS">AUTHORS</a></H2><PRE>
       Juergen Pfeifer.  Manual pages and adaptation for new curses by Eric S.
       Raymond.


                                                                 <STRONG><A HREF="form_hook.3x.html">form_hook(3x)</A></STRONG>
</PRE>
<div class="nav">
<ul>
<li><a href="#h2-NAME">NAME</a></li>
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
<li><a href="#h2-NOTES">NOTES</a></li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
<li><a href="#h2-AUTHORS">AUTHORS</a></li>
</ul>
</div>
</BODY>
</HTML>