.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: form_fieldtype.3x,v 1.23 2020/10/24 09:05:17 tom Exp $
+.\" $Id: form_fieldtype.3x,v 1.28 2020/12/12 17:11:21 tom Exp $
+.de bP
+.ie n .IP \(bu 4
+.el .IP \(bu 2
+..
.TH form_fieldtype 3X ""
.SH NAME
\fBform_fieldtype\fR \- define validation-field types
\fBFIELDTYPE *link_fieldtype(FIELDTYPE *\fP\fItype1\fP\fB,\fP
\fBFIELDTYPE *\fP\fItype2\fP\fB);\fP
.SH DESCRIPTION
+.SS new_fieldtype
The function \fBnew_fieldtype\fR creates a new field type usable for data
validation.
-You supply it with \fIfield_check\fR, a predicate to check the
+Its parameters are function pointers:
+.TP 5
+\fIfield_check\fR
+This function checks the
validity of an entered data string whenever the user attempts to leave a field.
+It has two arguments:
+.RS
+.bP
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
+field's buffer, sizes and other attributes.
+.bP
+The second argument is an
argument-block structure, about which more below.
+.RE
+.TP 5
+\fIchar_check\fR
+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.
+.SS free_fieldtype
.PP
-You also supply \fBnew_fieldtype\fR with \fIchar_check\fR,
-a function to validate input characters as they are entered; it will be passed
-the character to be checked and a pointer to an argument-block structure.
-.PP
-The function \fBfree_fieldtype\fR frees the space allocated for a given
-validation type.
+The \fBfree_fieldtype\fR function
+frees the space allocated for a given validation type by \fBnew_fieldtype\fP.
+.SS set_fieldtype_arg
.PP
The function \fBset_fieldtype_arg\fR associates
-three storage-management functions with a field type.
-The \fImake_arg\fR function is automatically applied to the
+three storage-management functions with a field type:
+.TP 5
+\fImake_arg\fR
+This function is automatically applied to the
list of arguments you give \fBset_field_type\fR 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 argument-block structures.
-They will be used by the forms-driver code.
-You must supply the \fImake_arg\fR function,
-the other two are optional, you may supply NULL for them.
-In this case it is assumed
+to a field.
+It stores the arguments in an allocated argument-block
+object which is used when validating input.
+.TP 5
+\fIcopy_arg\fR
+This function may be used by applications to copy argument-blocks.
+.TP 5
+\fIfree_arg\fR
+Frees an argument-block structure.
+.PP
+You must supply the \fImake_arg\fR function.
+The other two are optional: you may supply NULL for them.
+In this case, the form library assumes
that \fImake_arg\fR does not allocate memory but simply loads the
argument into a single scalar value.
-.PP
-The function \fBlink_fieldtype\fR creates
-a new field type from the two given types.
-They are connected by an logical 'OR'.
+.SS set_fieldtype_choice
.PP
The form driver requests \fBREQ_NEXT_CHOICE\fR and \fBREQ_PREV_CHOICE\fR 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.
+.PP
The \fBset_fieldtype_choice\fR
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.
+.SS link_fieldtype
+.PP
+The function \fBlink_fieldtype\fR creates
+a new field type from the two given types.
+They are connected by an logical 'OR'.
.SH RETURN VALUE
The pointer-valued routines return NULL on error.
They set \fBerrno\fP according to their success:
.B E_SYSTEM_ERROR
System error occurred (see \fBerrno\fR(3)).
.SH SEE ALSO
-\fBcurses\fR(3X), \fBform\fR(3X).
+\fBcurses\fR(3X),
+\fBform\fR(3X),
+\fBform_field_validation\fR(3X).
.SH NOTES
The header file \fB<form.h>\fR automatically includes the header file
\fB<curses.h>\fR.
-.PP
-All of the \fB(char *)\fR arguments of these functions should actually be
-\fB(void *)\fR. The type has been left uncorrected for strict compatibility
-with System V.
.SH PORTABILITY
These routines emulate the System V forms library.
They were not supported on
projects / ncurses.git / blobdiff