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31 .\" $Id: form_fieldtype.3x,v 1.21 2020/03/28 19:06:28 tom Exp $
32 .TH form_fieldtype 3X ""
34 \fBform_fieldtype\fR \- define validation-field types
36 \fB#include <form.h>\fR
38 FIELDTYPE *new_fieldtype(
39 bool (* const field_check)(FIELD *, const void *),
40 bool (* const char_check)(int, const void *));
42 int free_fieldtype(FIELDTYPE *fieldtype);
44 int set_fieldtype_arg(
46 void *(* const make_arg)(va_list *),
47 void *(* const copy_arg)(const void *),
48 void (* const free_arg)(void *));
50 int set_fieldtype_choice(
52 bool (* const next_choice)(FIELD *, const void *),
53 bool (* const prev_choice)(FIELD *, const void *));
55 FIELDTYPE *link_fieldtype(FIELDTYPE *type1,
59 The function \fBnew_fieldtype\fR creates a new field type usable for data
61 You supply it with \fIfield_check\fR, a predicate to check the
62 validity of an entered data string whenever the user attempts to leave a field.
63 The (FIELD *) argument is passed in so the validation predicate can see the
64 field's buffer, sizes and other attributes; the second argument is an
65 argument-block structure, about which more below.
67 You also supply \fBnew_fieldtype\fR with \fIchar_check\fR,
68 a function to validate input characters as they are entered; it will be passed
69 the character to be checked and a pointer to an argument-block structure.
71 The function \fBfree_fieldtype\fR frees the space allocated for a given
74 The function \fBset_fieldtype_arg\fR associates
75 three storage-management functions with a field type.
76 The \fImake_arg\fR function is automatically applied to the
77 list of arguments you give \fBset_field_type\fR when attaching validation
78 to a field; its job is to bundle these into an allocated argument-block
79 object which can later be passed to validation predicated.
80 The other two hook arguments should copy and free argument-block structures.
81 They will be used by the forms-driver code.
82 You must supply the \fImake_arg\fR function,
83 the other two are optional, you may supply NULL for them.
84 In this case it is assumed
85 that \fImake_arg\fR does not allocate memory but simply loads the
86 argument into a single scalar value.
88 The function \fBlink_fieldtype\fR creates
89 a new field type from the two given types.
90 They are connected by an logical 'OR'.
92 The form driver requests \fBREQ_NEXT_CHOICE\fR and \fBREQ_PREV_CHOICE\fR assume
93 that the possible values of a field form an ordered set, and provide the forms
94 user with a way to move through the set.
95 The \fBset_fieldtype_choice\fR
96 function allows forms programmers to define successor and predecessor functions
98 These functions take the field pointer and an
99 argument-block structure as arguments.
101 The pointer-valued routines return NULL on error.
102 They set \fBerrno\fP according to their success:
105 The routine succeeded.
108 Routine detected an incorrect or out-of-range argument.
111 System error occurred, e.g., malloc failure.
113 The integer-valued routines return one of the following codes on
117 The routine succeeded.
120 Routine detected an incorrect or out-of-range argument.
123 The field is already connected to a form.
126 The field is the current field.
129 System error occurred (see \fBerrno\fR(3)).
131 \fBcurses\fR(3X), \fBform\fR(3X).
133 The header file \fB<form.h>\fR automatically includes the header file
136 All of the \fB(char *)\fR arguments of these functions should actually be
137 \fB(void *)\fR. The type has been left uncorrected for strict compatibility
140 These routines emulate the System V forms library.
141 They were not supported on
142 Version 7 or BSD versions.
145 Manual pages and adaptation for new curses by Eric S. Raymond.