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. 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.
+ 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
@@ -86,20 +90,24 @@
The function free_fieldtype frees the space allocated for
a given validation type.
- The function set_fieldtype associates three storage-man-
- agement 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 argu-
- ment-block structures. They will be used by the forms-
- driver code. You must supply the mak_arg function, the
- other two are optional, you may supply NULL for them. In
- this case it is assumed, that mak_arg doesn't allocate
+ 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 argu-
+ ment-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
@@ -111,17 +119,24 @@
-
RETURN VALUE
- The pointer-valued routines return NULL on error.
+
+ 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 argu-
+ ment.
+
+ 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_SYSTEM_ERROR
- System error occurred (see errno).
-
E_BAD_ARGUMENT
Routine detected an incorrect or out-of-range argu-
ment.
@@ -129,14 +144,20 @@
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).
+