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| .\" $Id: form_fieldtype.3x,v 1.14 2006/11/04 17:12:00 tom Exp $ |
| .TH form_fieldtype 3X "" |
| .SH NAME |
| \fBform_fieldtype\fR - define validation-field types |
| .SH SYNOPSIS |
| \fB#include <form.h>\fR |
| .br |
| FIELDTYPE *new_fieldtype( |
| bool (* const field_check)(FIELD *, const void *), |
| bool (* const char_check)(int, const void *)); |
| .br |
| int free_fieldtype(FIELDTYPE *fieldtype); |
| .br |
| int set_fieldtype_arg( |
| FIELDTYPE *fieldtype, |
| void *(* const make_arg)(va_list *), |
| void *(* const copy_arg)(const void *), |
| void (* const free_arg)(void *)); |
| .br |
| int set_fieldtype_choice( |
| FIELDTYPE *fieldtype, |
| bool (* const next_choice)(FIELD *, const void *), |
| bool (* const prev_choice)(FIELD *, const void *)); |
| .br |
| FIELDTYPE *link_fieldtype(FIELDTYPE *type1, |
| FIELDTYPE *type2); |
| .br |
| .SH DESCRIPTION |
| 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 |
| validity of an entered data string whenever the user attempts to leave a field. |
| 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. |
| .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. |
| .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 |
| 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 |
| 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'. |
| .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. |
| 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. |
| .SH RETURN VALUE |
| The pointer-valued routines return NULL on error. |
| They set errno according to their success: |
| .TP 5 |
| .B E_OK |
| The routine succeeded. |
| .TP 5 |
| .B E_BAD_ARGUMENT |
| Routine detected an incorrect or out-of-range argument. |
| .TP 5 |
| .B E_SYSTEM_ERROR |
| System error occurred, e.g., malloc failure. |
| .PP |
| The integer-valued routines return one of the following codes on |
| error: |
| .TP 5 |
| .B E_OK |
| The routine succeeded. |
| .TP 5 |
| .B E_BAD_ARGUMENT |
| Routine detected an incorrect or out-of-range argument. |
| .TP 5 |
| .B E_CONNECTED |
| The field is already connected to a form. |
| .TP 5 |
| .B E_CURRENT |
| The field is the current field. |
| .TP 5 |
| .B E_SYSTEM_ERROR |
| System error occurred (see \fBerrno\fR). |
| .SH SEE ALSO |
| \fBcurses\fR(3X), \fBform\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 |
| Version 7 or BSD versions. |
| .SH AUTHORS |
| Juergen Pfeifer. Manual pages and adaptation for new curses by Eric |
| S. Raymond. |
| .\"# |
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