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<H1>form_fieldtype 3x</H1>
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<PRE>
<!-- Manpage converted by man2html 3.0.1 -->
<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>NAME</H2><PRE>
<STRONG>form_fieldtype</STRONG> - define validation-field types
</PRE>
<H2>SYNOPSIS</H2><PRE>
<STRONG>#include</STRONG> <STRONG><form.h></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>DESCRIPTION</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 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 <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 validation 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 argu-
ment-block object which can later be passed to validation
predicated. 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_fieldtype_choice</STRONG> func-
tion 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>RETURN VALUE</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 argu-
ment.
<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 argu-
ment.
<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</STRONG>).
</PRE>
<H2>SEE ALSO</H2><PRE>
<STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="form.3x.html">form(3x)</A></STRONG>.
</PRE>
<H2>NOTES</H2><PRE>
The header file <STRONG><form.h></STRONG> automatically includes the header
file <STRONG><curses.h></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>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.
<STRONG><A HREF="form_fieldtype.3x.html">form_fieldtype(3x)</A></STRONG>
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