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<PRE>
<!-- Manpage converted by man2html 3.0.1 -->
</PRE>
<H2>NAME</H2><PRE>
<B>form_fieldtype</B> - define validation-field types
</PRE>
<H2>SYNOPSIS</H2><PRE>
<B>#include</B> <B><form.h></B>
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>DESCRIPTION</H2><PRE>
The function <B>new_fieldtype</B> creates a new field type usable
for data validation. You supply it with <I>field</I><B>_</B><I>check</I>, a
predicate to check the validity of an entered data string
whenever the user attempt to leave a field. The (FIELD *)
argument is passed in so the validation predicate 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 <B>new_fieldtype</B> with <I>char</I><B>_</B><I>check</I>, 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 <B>free_fieldtype</B> frees the space allocated for
a given validation type.
The function <B>set_fieldtype</B> associates three storage-man-
agement functions with a field type. The <I>mak</I><B>_</B><I>arg</I> function
is automatically applied to the list of arguments you give
<B>set_field_type</B> 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 predicated.
The other two hook arguments should copy and free argu-
ment-block structures. They will be used by the forms-
driver code. You must supply the <I>mak</I><B>_</B><I>arg</I> function, the
other two are optional, you may supply NULL for them. In
this case it is assumed, that <I>mak</I><B>_</B><I>arg</I> doesn't allocate
memory but simply loads the argument into a single scalar
value.
The form driver requests <B>REQ_NEXT_CHOICE</B> and
<B>REQ_PREV_CHOICE</B> 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 <B>set_fieldtype_choice</B> func-
tion allows forms programmers to define successor and pre-
decessor functions for the field type. These functions
take the field pointer and an argument-block structure as
arguments.
</PRE>
<H2>RETURN VALUE</H2><PRE>
The pointer-valued routines return NULL on error.
The integer-valued routines return one of the following
codes on error:
<B>E_OK</B> The routine succeeded.
<B>E_SYSTEM_ERROR</B>
System error occurred (see <B>errno</B>).
<B>E_BAD_ARGUMENT</B>
Routine detected an incorrect or out-of-range argu-
ment.
<B>E_CONNECTED</B>
The field is already connected to a form.
</PRE>
<H2>SEE ALSO</H2><PRE>
<B><A HREF="ncurses.3x.html">curses(3x)</A></B>, <B><A HREF="form.3x.html">form(3x)</A></B>.
</PRE>
<H2>NOTES</H2><PRE>
The header file <B><form.h></B> automatically includes the header
file <B><curses.h></B>.
All of the <B>(char</B> <B>*)</B> arguments of these functions should
actually be <B>(void</B> <B>*)</B>. The type has been left uncorrected
for strict compatibility with System V.
</PRE>
<H2>PORTABILITY</H2><PRE>
These routines emulate the System V forms library. They
were not supported on Version 7 or BSD versions.
</PRE>
<H2>AUTHORS</H2><PRE>
Juergen Pfeifer. Manual pages and adaptation for new
curses by Eric S. Raymond.
</PRE>
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