form_fieldtype.3x - Man Page
define validation-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:
- 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_type when 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 an 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.
Authors
Juergen Pfeifer. Manual pages and adaptation for new curses by Eric S. Raymond.
See Also
curses(3X), form(3X), form_field_validation(3X)
Referenced By
The man pages free_fieldtype.3x(3), link_fieldtype.3x(3), new_fieldtype.3x(3), set_fieldtype_arg.3x(3) and set_fieldtype_choice.3x(3) are aliases of form_fieldtype.3x(3).