fieldtype

Section: Misc. Reference Manual Pages (3FORM)
Updated:
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NAME

form_fieldtype - define validation-field types  

SYNOPSIS

#include <form.h>

FIELDTYPE *new_fieldtype(
    bool (* const field_check)(FIELD *, const void *),
    bool (* const char_check)(int, const void *));
int free_fieldtype(FIELDTYPE *fieldtype);

int set_fieldtype_arg(
    FIELDTYPE *fieldtype,
    void *(* const make_arg)(va_list *),
    void *(* const copy_arg)(const void *),
    void  (* const free_arg)(void *));
int set_fieldtype_choice(
    FIELDTYPE *fieldtype,
    bool (* const next_choice)(FIELD *, const void *),
    bool (* const prev_choice)(FIELD *, const void *));

FIELDTYPE *link_fieldtype(FIELDTYPE *type1,
                          FIELDTYPE *type2);  

DESCRIPTION

 

new_fieldtype

The function new_fieldtype creates a new field type usable for data validation. Its parameters are function pointers:
field_check
This function checks the validity of an entered data string whenever the user attempts to leave a field. It has two arguments:

 .IP • 4 The (FIELD *) argument is passed in so the validation predicate can see the field's buffer, sizes and other attributes.
 .IP • 4 The second argument is an argument-block structure, about which more below.
char_check
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.
 

free_fieldtype

The free_fieldtype function frees the space allocated for a given validation type by new_fieldtype.  

set_fieldtype_arg

The function set_fieldtype_arg associates three storage-management functions with a field type:

make_arg
This function is automatically applied to the list of arguments you give set_field_type when attaching validation to a field. It stores the arguments in an allocated argument-block object which is used when validating input.
copy_arg
This function may be used by applications to copy argument-blocks.
free_arg
Frees an argument-block structure.

You must supply the make_arg function. The other two are optional: you may supply NULL for them. In this case, the form library assumes that make_arg does not allocate memory but simply loads the argument into a single scalar value.  

set_fieldtype_choice

The form driver requests REQ_NEXT_CHOICE and REQ_PREV_CHOICE 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 set_fieldtype_choice 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.  

link_fieldtype

The function link_fieldtype creates a new field type from the two given types. They are connected by an logical 'OR'.  

RETURN VALUE

The pointer-valued routines return NULL on error. They set errno according to their success:
E_OK
The routine succeeded.
E_BAD_ARGUMENT
Routine detected an incorrect or out-of-range argument.
E_SYSTEM_ERROR
System error occurred, e.g., malloc failure.

The integer-valued routines return one of the following codes on error:

E_OK
The routine succeeded.
E_BAD_ARGUMENT
Routine detected an incorrect or out-of-range argument.
E_CONNECTED
The field is already connected to a form.
E_CURRENT
The field is the current field.
E_SYSTEM_ERROR
System error occurred (see errno(3)).
 

SEE ALSO

ncurses(3NCURSES), form(3FORM), field_validation(3FORM).  

NOTES

The header file <form.h> automatically includes the header file <curses.h>.  

PORTABILITY

These routines emulate the System V forms library. They were not supported on Version 7 or BSD versions.  

AUTHORS

Juergen Pfeifer. Manual pages and adaptation for new curses by Eric S. Raymond.


 

Index

NAME
SYNOPSIS
DESCRIPTION
new_fieldtype
free_fieldtype
set_fieldtype_arg
set_fieldtype_choice
link_fieldtype
RETURN VALUE
SEE ALSO
NOTES
PORTABILITY
AUTHORS

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Time: 14:13:10 GMT, March 28, 2024