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30 .\" $Id: form_fieldtype.3x,v 1.18 2018/07/28 22:08:59 tom Exp $
31 .TH form_fieldtype 3X ""
33 \fBform_fieldtype\fR \- define validation-field types
35 \fB#include <form.h>\fR
37 FIELDTYPE *new_fieldtype(
38 bool (* const field_check)(FIELD *, const void *),
39 bool (* const char_check)(int, const void *));
41 int free_fieldtype(FIELDTYPE *fieldtype);
43 int set_fieldtype_arg(
45 void *(* const make_arg)(va_list *),
46 void *(* const copy_arg)(const void *),
47 void (* const free_arg)(void *));
49 int set_fieldtype_choice(
51 bool (* const next_choice)(FIELD *, const void *),
52 bool (* const prev_choice)(FIELD *, const void *));
54 FIELDTYPE *link_fieldtype(FIELDTYPE *type1,
58 The function \fBnew_fieldtype\fR creates a new field type usable for data
60 You supply it with \fIfield_check\fR, a predicate to check the
61 validity of an entered data string whenever the user attempts to leave a field.
62 The (FIELD *) argument is passed in so the validation predicate can see the
63 field's buffer, sizes and other attributes; the second argument is an
64 argument-block structure, about which more below.
66 You also supply \fBnew_fieldtype\fR with \fIchar_check\fR,
67 a function to validate input characters as they are entered; it will be passed
68 the character to be checked and a pointer to an argument-block structure.
70 The function \fBfree_fieldtype\fR frees the space allocated for a given
73 The function \fBset_fieldtype_arg\fR associates
74 three storage-management functions with a field type.
75 The \fImake_arg\fR function is automatically applied to the
76 list of arguments you give \fBset_field_type\fR when attaching validation
77 to a field; its job is to bundle these into an allocated argument-block
78 object which can later be passed to validation predicated.
79 The other two hook arguments should copy and free argument-block structures.
80 They will be used by the forms-driver code.
81 You must supply the \fImake_arg\fR function,
82 the other two are optional, you may supply NULL for them.
83 In this case it is assumed
84 that \fImake_arg\fR does not allocate memory but simply loads the
85 argument into a single scalar value.
87 The function \fBlink_fieldtype\fR creates
88 a new field type from the two given types.
89 They are connected by an logical 'OR'.
91 The form driver requests \fBREQ_NEXT_CHOICE\fR and \fBREQ_PREV_CHOICE\fR assume
92 that the possible values of a field form an ordered set, and provide the forms
93 user with a way to move through the set.
94 The \fBset_fieldtype_choice\fR
95 function allows forms programmers to define successor and predecessor functions
97 These functions take the field pointer and an
98 argument-block structure as arguments.
100 The pointer-valued routines return NULL on error.
101 They set errno according to their success:
104 The routine succeeded.
107 Routine detected an incorrect or out-of-range argument.
110 System error occurred, e.g., malloc failure.
112 The integer-valued routines return one of the following codes on
116 The routine succeeded.
119 Routine detected an incorrect or out-of-range argument.
122 The field is already connected to a form.
125 The field is the current field.
128 System error occurred (see \fBerrno\fR).
130 \fBcurses\fR(3X), \fBform\fR(3X).
132 The header file \fB<form.h>\fR automatically includes the header file
135 All of the \fB(char *)\fR arguments of these functions should actually be
136 \fB(void *)\fR. The type has been left uncorrected for strict compatibility
139 These routines emulate the System V forms library.
140 They were not supported on
141 Version 7 or BSD versions.
144 Manual pages and adaptation for new curses by Eric S. Raymond.