.\"	$NetBSD: form_fieldtype.3,v 1.11 2010/03/22 21:58:31 joerg Exp $
.\"
.\" Copyright (c) 2001
.\"	Brett Lymn - blymn@baea.com.au, brett_lymn@yahoo.com.au
.\"
.\" This code is donated to The NetBSD Foundation by the author.
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.Dd January 1, 2001
.Dt FORMS 3
.Os
.Sh NAME
.Nm free_fieldtype ,
.Nm link_fieldtype ,
.Nm new_fieldtype ,
.Nm set_fieldtype_arg ,
.Nm set_fieldtype_choice
.Nd form library
.Sh LIBRARY
.Lb libform
.Sh SYNOPSIS
.In form.h
.Ft int
.Fn free_fieldtype "FIELDTYPE *fieldtype"
.Ft FIELDTYPE *
.Fn link_fieldtype "FIELDTYPE *type1" "FIELDTYPE *type2"
.Ft FIELDTYPE *
.Fo new_fieldtype
.Fa "int (*field_check)(FIELD *, char *)"
.Fa "int (*char_check)(int, char *)"
.Fc
.Ft int
.Fo "set_fieldtype_arg"
.Fa "FIELDTYPE *fieldtype"
.Fa "char * (*make_args)(va_list *)"
.Fa "char * (*copy_args)(char *)"
.Fa "void (*free_args)(char *)"
.Fc
.Ft int
.Fo set_fieldtype_choice
.Fa "FIELDTYPE *fieldtype"
.Fa "int (*next_choice)(FIELD *, char *)"
.Fa "int (*prev_choice)(FIELD *, char *)"
.Fc
.Sh DESCRIPTION
The function
.Fn free_fieldtype
frees the storage associated with the field type and destroys it.
The function
.Fn link_fieldtype
links together the two given field types to produce a new field type.
A new field type can be created by calling
.Fn new_fieldtype
which requires pointers to two functions which perform validation, the
.Fa field_check
function must validate the field contents and return
.Dv TRUE
if they are acceptable and
.Dv FALSE
if they are not.
The
.Fa char_check
validates the character input into the field, this function will be
called for each character entered, if the character can be entered
into the field then
.Fa char_check
must return
.Dv TRUE .
Neither
.Fa field_check
nor
.Fa char_check
may be
.Dv NULL .
The functions for handling the field type arguments can
be defined by using the
.Fn set_fieldtype_arg
function, the
.Fa make_args
function is used to create new arguments for the fieldtype, the
.Fa copy_args
is used to copy the fieldtype arguments to a new arguments structure
and
.Fa free_args
is used to destroy the fieldtype arguments and release any associated
storage, none of these function pointers may be
.Dv NULL .
The field type choice functions can be set by calling
.Fn set_fieldtype_choice ,
the
.Fa next_choice
and
.Fa prev_choice
specify the next and previous choice functions for the field type.
These functions must perform the necessary actions to select the next
or previous choice for the field, updating the field buffer if
necessary.
The choice functions must return
.Dv TRUE
if the function succeeded and
.Dv FALSE
otherwise.
.Sh RETURN VALUES
Functions returning pointers will return
.Dv NULL
if an error is detected.
The functions that return an int will return one of the following error
values:
.Pp
.Bl -tag -width E_UNKNOWN_COMMAND -compact
.It Er E_OK
The function was successful.
.It Er E_BAD_ARGUMENT
The function was passed a bad argument.
.It Er E_CONNECTED
The field is connected to a form.
.El
.Sh SEE ALSO
.Xr curses 3 ,
.Xr forms 3
.Sh NOTES
The header
.In form.h
automatically includes both
.In curses.h
and
.In eti.h .