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<H1 class="no-header">form_fieldtype 3x</H1>
<PRE>
<STRONG><A HREF="form_fieldtype.3x.html">form_fieldtype(3x)</A></STRONG>                                          <STRONG><A HREF="form_fieldtype.3x.html">form_fieldtype(3x)</A></STRONG>




</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
       <STRONG>form_fieldtype</STRONG> - define validation-field types


</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
       <STRONG>#include</STRONG> <STRONG>&lt;form.h&gt;</STRONG>
       FIELDTYPE *new_fieldtype(
           bool (* const field_check)(FIELD *, const void *),
           bool (* const char_check)(int, const void *));
       int free_fieldtype(FIELDTYPE *fieldtype);
       int set_fieldtype_arg(
           FIELDTYPE *fieldtype,
           void *(* const make_arg)(va_list *),
           void *(* const copy_arg)(const void *),
           void  (* const free_arg)(void *));
       int set_fieldtype_choice(
           FIELDTYPE *fieldtype,
           bool (* const next_choice)(FIELD *, const void *),
           bool (* const prev_choice)(FIELD *, const void *));
       FIELDTYPE *link_fieldtype(FIELDTYPE *type1,
                                 FIELDTYPE *type2);


</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
       The  function  <STRONG>new_fieldtype</STRONG>  creates  a new field type usable for data
       validation.  You supply it with <EM>field</EM><STRONG>_</STRONG><EM>check</EM>, a predicate to  check  the
       validity  of an entered data string whenever the user attempts to leave
       a field.  The (FIELD *) argument is passed in so the validation  predi-
       cate can see the field's buffer, sizes and other attributes; the second
       argument is an argument-block structure, about which more below.

       You also supply <STRONG>new_fieldtype</STRONG> with <EM>char</EM><STRONG>_</STRONG><EM>check</EM>, a function  to  validate
       input  characters  as they are entered; it will be passed the character
       to be checked and a pointer to an argument-block structure.

       The function <STRONG>free_fieldtype</STRONG> frees the space allocated for a given vali-
       dation type.

       The  function  <STRONG>set_fieldtype_arg</STRONG>  associates  three  storage-management
       functions with a field type.  The <EM>make</EM><STRONG>_</STRONG><EM>arg</EM>  function  is  automatically
       applied to the list of arguments you give <STRONG>set_field_type</STRONG> when attaching
       validation to a field; its job is to bundle  these  into  an  allocated
       argument-block  object  which  can later be passed to validation predi-
       cated.  The other two hook arguments should  copy  and  free  argument-
       block  structures.   They  will  be used by the forms-driver code.  You
       must supply the <EM>make</EM><STRONG>_</STRONG><EM>arg</EM> function, the other two are optional, you  may
       supply  NULL  for  them.  In this case it is assumed that <EM>make</EM><STRONG>_</STRONG><EM>arg</EM> does
       not allocate memory but simply loads the argument into a single  scalar
       value.

       The function <STRONG>link_fieldtype</STRONG> creates a new field type from the two given
       types.  They are connected by an logical 'OR'.

       The form driver requests  <STRONG>REQ_NEXT_CHOICE</STRONG>  and  <STRONG>REQ_PREV_CHOICE</STRONG>  assume
       that  the  possible  values of a field form an ordered set, and provide
       the forms user with a way to move  through  the  set.   The  <STRONG>set_field-</STRONG>
       <STRONG>type_choice</STRONG>  function  allows forms programmers to define successor and
       predecessor functions for the field type.   These  functions  take  the
       field pointer and an argument-block structure as arguments.


</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
       The  pointer-valued  routines  return  NULL  on  error.  They set errno
       according to their success:

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

       <STRONG>E_BAD_ARGUMENT</STRONG>
            Routine detected an incorrect or out-of-range argument.

       <STRONG>E_SYSTEM_ERROR</STRONG>
            System error occurred, e.g., malloc failure.

       The integer-valued routines return one of the following codes on error:

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

       <STRONG>E_BAD_ARGUMENT</STRONG>
            Routine detected an incorrect or out-of-range argument.

       <STRONG>E_CONNECTED</STRONG>
            The field is already connected to a form.

       <STRONG>E_CURRENT</STRONG>
            The field is the current field.

       <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>.

       All  of  the  <STRONG>(char</STRONG>  <STRONG>*)</STRONG> arguments of these functions should actually be
       <STRONG>(void</STRONG> <STRONG>*)</STRONG>.  The type has been left uncorrected for strict  compatibility
       with System V.


</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
       These  routines emulate the System V forms library.  They were not sup-
       ported 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_fieldtype.3x.html">form_fieldtype(3x)</A></STRONG>
</PRE>
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<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>
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