form_fieldtype(3) UNIX Programmer's Manual form_fieldtype(3)
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 func-
tion 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.
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form_fieldtype(3) UNIX Programmer's Manual form_fieldtype(3)
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 pro-
grammers 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.
The integer-valued routines return one of the following
codes on error:
E_OK The routine succeeded.
E_SYSTEM_ERROR
System error occurred (see errno).
E_BAD_ARGUMENT
Routine detected an incorrect or out-of-range argument.
E_CONNECTED
The field is already connected to a form.
curses(3), form(3).
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.
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