free_fieldtype3x
Define validation-field types
Part of form_fieldtype(3x).
Usage
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);
Overview
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:
- •
-
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.
- 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 argument-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 storage-management functions with a field type:
- make_arg
-
This function is automatically applied to the list of arguments you give
set_field_typewhen attaching validation to a field. It stores the arguments in an allocated argument-block object which is used when validating input.
- copy_arg
-
This function may be used by applications to copy argument-blocks.
- free_arg
-
Frees an argument-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 argument-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 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(3)).
Portability
These routines emulate the System V forms library. They were not supported on Version 7 or BSD versions.