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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO | NOTES | PORTABILITY | AUTHORS | COLOPHON |
form_fieldtype(3X) form_fieldtype(3X)
form_fieldtype - define validation-field types
#include <form.h>
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);
The function new_fieldtype creates a new field type usable for data
validation. You supply it with field_check, 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 new_fieldtype with char_check, 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 free_fieldtype frees the space allocated for a given
validation type.
The function set_fieldtype_arg associates three storage-management
functions with a field type. The make_arg function is automatically
applied to the list of arguments you give set_field_type 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 argument-block structures. They will be used by the forms-
driver code. You must supply the make_arg function, the other two
are optional, you may supply NULL for them. In this case it is
assumed that make_arg does not allocate memory but simply loads the
argument into a single scalar value.
The function link_fieldtype creates a new field type from the two
given types. They are connected by an logical 'OR'.
The form driver requests REQ_NEXT_CHOICE and REQ_PREV_CHOICE 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
set_fieldtype_choice 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.
The pointer-valued routines return NULL on error. They set errno
according to their success:
E_OK The routine succeeded.
E_BAD_ARGUMENT
Routine detected an incorrect or out-of-range argument.
E_SYSTEM_ERROR
System error occurred, e.g., malloc failure.
The integer-valued routines return one of the following codes on
error:
E_OK The routine succeeded.
E_BAD_ARGUMENT
Routine detected an incorrect or out-of-range argument.
E_CONNECTED
The field is already connected to a form.
E_CURRENT
The field is the current field.
E_SYSTEM_ERROR
System error occurred (see errno).
curses(3X), form(3X).
The header file <form.h> automatically includes the header file
<curses.h>.
All of the (char *) arguments of these functions should actually be
(void *). The type has been left uncorrected for strict
compatibility with System V.
These routines emulate the System V forms library. They were not
supported on Version 7 or BSD versions.
Juergen Pfeifer. Manual pages and adaptation for new curses by Eric
S. Raymond.
This page is part of the ncurses (new curses) project. Information
about the project can be found at
⟨https://www.gnu.org/software/ncurses/ncurses.html⟩. If you have a
bug report for this manual page, send it to
bug-ncurses-request@gnu.org. This page was obtained from the
project's upstream Git mirror of the CVS repository
⟨git://ncurses.scripts.mit.edu/ncurses.git⟩ on 2017-07-05. If you
discover any rendering problems in this HTML version of the page, or
you believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
form_fieldtype(3X)