'\" t.\"***************************************************************************.\" Copyright (c) 1998-2002,2003 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_fieldtype.3x,v 1.12 2003/05/10 20:33:49 jmc Exp $.TH form_fieldtype 3X "".SH NAME\fBform_fieldtype\fR - define validation-field types.SH SYNOPSIS\fB#include <form.h>\fR.brFIELDTYPE *new_fieldtype(    bool (* const field_check)(FIELD *, const void *),    bool (* const char_check)(int, const void *));.brint free_fieldtype(FIELDTYPE *fieldtype);.brint set_fieldtype_arg(    FIELDTYPE *fieldtype,    void *(* const make_arg)(va_list *),    void *(* const copy_arg)(const void *),    void  (* const free_arg)(void *));.brint set_fieldtype_choice(    FIELDTYPE *fieldtype,    bool (* const next_choice)(FIELD *, const void *),    bool (* const prev_choice)(FIELD *, const void *));.brFIELDTYPE *link_fieldtype(FIELDTYPE *type1,                          FIELDTYPE *type2);.br.SH DESCRIPTIONThe function \fBnew_fieldtype\fR creates a new field type usable for datavalidation.  You supply it with \fIfield_check\fR, a predicate to check thevalidity 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 thefield's buffer, sizes and other attributes; the second argument is anargument-block structure, about which more below.You also supply \fBnew_fieldtype\fR with \fIchar_check\fR,a function to validate input characters as they are entered; it will be passedthe character to be checked and a pointer to an argument-block structure.The function \fBfree_fieldtype\fR frees the space allocated for a givenvalidation type.The function \fBset_fieldtype_arg\fR associates three storage-management functionswith a field type.The \fImake_arg\fR function is automatically applied to thelist of arguments you give \fBset_field_type\fR when attaching validationto a field; its job is to bundle these into an allocated argument-blockobject 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 \fImake_arg\fR function,the other two are optional, you may supply NULL for them.In this case it is assumedthat \fImake_arg\fR does not allocate memory but simply loads theargument into a single scalar value.The function \fBlink_fieldtype\fR createsa new field type from the two given types.They are connected by an logical 'OR'.The form driver requests \fBREQ_NEXT_CHOICE\fR and \fBREQ_PREV_CHOICE\fR assumethat the possible values of a field form an ordered set, and provide the formsuser with a way to move through the set.The \fBset_fieldtype_choice\fRfunction allows forms programmers to define successor and predecessor functionsfor the field type.These functions take the field pointer and anargument-block structure as arguments..SH RETURN VALUEThe pointer-valued routines return NULL on error.The integer-valued routines return one of the following codes onerror:.TP 5\fBE_OK\fRThe routine succeeded..TP 5\fBE_SYSTEM_ERROR\fRSystem error occurred (see \fBerrno\fR)..TP 5\fBE_BAD_ARGUMENT\fRRoutine detected an incorrect or out-of-range argument..TP 5\fBE_CONNECTED\fRThe field is already connected to a form..SH SEE ALSO\fBcurses\fR(3X), \fBform\fR(3X)..SH NOTESThe header file \fB<form.h>\fR automatically includes the header file\fB<curses.h>\fR.All of the \fB(char *)\fR arguments of these functions should actually be\fB(void *)\fR.  The type has been left uncorrected for strict compatibilitywith System V..SH PORTABILITYThese routines emulate the System V forms library.  They were not supported onVersion 7 or BSD versions..SH AUTHORSJuergen Pfeifer.  Manual pages and adaptation for new curses by EricS. Raymond..\"#.\"# The following sets edit modes for GNU EMACS.\"# Local Variables:.\"# mode:nroff.\"# fill-column:79.\"# End: