form_fieldtype
Section: Library calls (3X)
Updated: 202-0-18
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NAME
form_fieldtype -
define validatio-field types
SYNOPSIS
#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);
DESCRIPTION
new_fieldtype
The function
new_fieldtype creates a new field type usable for data
validation.
Its parameters are function pointers:
- field_check
-
This function checks the
validity of an entered data string whenever the user attempts to leave a field.
It has two arguments:
-
.IP * 4
The (FIELD *) argument is passed in so the validation predicate can see the
field's buffer, sizes and other attributes.
.IP * 4
The second argument is an
argumen-block structure, about which more below.
- char_check
-
This function validates input characters as they are entered.
The form library passes it the character to be checked
and a pointer to an argumen-block structure.
free_fieldtype
The
free_fieldtype function
frees the space allocated for a given validation type by
new_fieldtype.
set_fieldtype_arg
The function
set_fieldtype_arg associates
three storag-management functions with a field type:
- make_arg
-
This function is automatically applied to the
list of arguments you give set_field_type when attaching validation
to a field.
It stores the arguments in an allocated argumen-block
object which is used when validating input.
- copy_arg
-
This function may be used by applications to copy argumen-blocks.
- free_arg
-
Frees an argumen-block structure.
You must supply the make_arg function.
The other two are optional: you may supply
NULL
for them.
In this case, the form library assumes
that make_arg does not allocate memory but simply loads the
argument into a single scalar value.
set_fieldtype_choice
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
argumen-block structure as arguments.
link_fieldtype
The function
link_fieldtype creates
a new field type from the two given types.
They are connected by a logical "or".
RETURN VALUE
The pointe-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 ou-o-range argument.
- E_SYSTEM_ERROR
-
System error occurred, e.g., malloc failure.
The intege-valued routines return one of the following codes on
error:
- E_OK
-
The routine succeeded.
- E_BAD_ARGUMENT
-
Routine detected an incorrect or ou-o-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(3)).
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.
SEE ALSO
curses(3X),
form(3X),
form_field_validation(3X)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- new_fieldtype
-
- free_fieldtype
-
- set_fieldtype_arg
-
- set_fieldtype_choice
-
- link_fieldtype
-
- RETURN VALUE
-
- PORTABILITY
-
- AUTHORS
-
- SEE ALSO
-
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