form_field
Section: Miscellaneous Library Functions (3X)
Updated:
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NAME
form_fieldtype - define validation-field types
SYNOPSIS
#include <form.h>
FIELDTYPE *new_fieldtype(int (*field_check)(FIELD *, char *),
int (*char_check)(int, char *));
int free_fieldtype(FIELDTYPE *fieldtype);
in set_fieldtype_arg(FIELDTYPE *fieldtype
char *(*mak_arg)(va_list *),
char *(*copy_arg)(char *),
void (*free_arg)(char *));
in set_fieldtype_choice(FIELDTYPE *fieldtype
int (*next_choice)(FIELD *, char *),
int (*prev_choice)(FIELD *, char *));
FIELDTYPE *link_fieldtype(FIELDYPE *type1, FIELDTYPE *type2);
DESCRIPTION
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 attempt to leave a field.
Thhe (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 associates three storage-management functions
with a field type. The mak_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.
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.
RETURN VALUE
The character-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.
SEE ALSO
curses(3X), form(3X).
NOTES
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.
PORTABILITY
These routines emulate the System V forms library. They were not supported on
Version 7 or BSD versions.
AUTHORS
Juergen Pfeifer. Manual pages and adaptation for new curses by Eric
S. Raymond.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- SEE ALSO
-
- NOTES
-
- PORTABILITY
-
- AUTHORS
-
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