1form_fieldtype(3X) form_fieldtype(3X)
2
6 form_fieldtype - define validation-field types
7
9 #include <form.h>
10 FIELDTYPE *new_fieldtype(
11 bool (* const field_check)(FIELD *, const void *),
12 bool (* const char_check)(int, const void *));
13 int free_fieldtype(FIELDTYPE *fieldtype);
14 int set_fieldtype_arg(
15 FIELDTYPE *fieldtype,
16 void *(* const make_arg)(va_list *),
17 void *(* const copy_arg)(const void *),
18 void (* const free_arg)(void *));
19 int set_fieldtype_choice(
20 FIELDTYPE *fieldtype,
21 bool (* const next_choice)(FIELD *, const void *),
22 bool (* const prev_choice)(FIELD *, const void *));
23 FIELDTYPE *link_fieldtype(FIELDTYPE *type1,
24 FIELDTYPE *type2);
25
27 The function new_fieldtype creates a new field type usable for data
28 validation. You supply it with field_check, a predicate to check the
29 validity of an entered data string whenever the user attempts to leave
30 a field. The (FIELD *) argument is passed in so the validation predi‐
31 cate can see the field's buffer, sizes and other attributes; the second
32 argument is an argument-block structure, about which more below.
33 You also supply new_fieldtype with char_check, a function to validate
35 input characters as they are entered; it will be passed the character
36 to be checked and a pointer to an argument-block structure.
37 The function free_fieldtype frees the space allocated for a given vali‐
39 dation type.
40 The function set_fieldtype_arg associates three storage-management
42 functions with a field type. The make_arg function is automatically
43 applied to the list of arguments you give set_field_type when attaching
44 validation to a field; its job is to bundle these into an allocated
45 argument-block object which can later be passed to validation predi‐
46 cated. The other two hook arguments should copy and free argument-
47 block structures. They will be used by the forms-driver code. You
48 must supply the make_arg function, the other two are optional, you may
49 supply NULL for them. In this case it is assumed that make_arg does
50 not allocate memory but simply loads the argument into a single scalar
51 value.
52 The function link_fieldtype creates a new field type from the two given
54 types. They are connected by an logical 'OR'.
55 The form driver requests REQ_NEXT_CHOICE and REQ_PREV_CHOICE assume
57 that the possible values of a field form an ordered set, and provide
58 the forms user with a way to move through the set. The set_field‐
59 type_choice function allows forms programmers to define successor and
60 predecessor functions for the field type. These functions take the
61 field pointer and an argument-block structure as arguments.
62
64 The pointer-valued routines return NULL on error. They set errno
65 according to their success:
66 E_OK The routine succeeded.
68 E_BAD_ARGUMENT
70 Routine detected an incorrect or out-of-range argument.
71 E_SYSTEM_ERROR
73 System error occurred, e.g., malloc failure.
74 The integer-valued routines return one of the following codes on error:
76 E_OK The routine succeeded.
78 E_BAD_ARGUMENT
80 Routine detected an incorrect or out-of-range argument.
81 E_CONNECTED
83 The field is already connected to a form.
84 E_CURRENT
86 The field is the current field.
87 E_SYSTEM_ERROR
89 System error occurred (see errno(3)).
90
92 curses(3X), form(3X).
93
95 The header file <form.h> automatically includes the header file
96 <curses.h>.
97 All of the (char *) arguments of these functions should actually be
99 (void *). The type has been left uncorrected for strict compatibility
100 with System V.
101
103 These routines emulate the System V forms library. They were not sup‐
104 ported on Version 7 or BSD versions.
105
107 Juergen Pfeifer. Manual pages and adaptation for new curses by Eric S.
108 Raymond.
109 form_fieldtype(3X)