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form_fldtype(3)

forms fieldtype routines

From the original Amiga UNIX 2.1 manual. Some things it mentions may not be in this release.

NAME

form_fieldtype: new_fieldtype, free_fieldtype, set_fieldtype_arg, set_fieldtype_choice, link_fieldtype - forms fieldtype routines

SYNOPSIS

#include <form.h>

FIELDTYPE *new_fieldtype(int (* field_check)(FIELD *, char *),
     int (* char_check)(int, char *));

int free_fieldtype(FIELDTYPE *fieldtype);
int set_fieldtype_arg(FIELDTYPE *fieldtype,
     char *(* mak_arg)(va_list *),
     char *(* copy_arg)(char *), void (* free_arg)(char *));

int set_fieldtype_choice(FIELDTYPE *fieldtype,
     int (* next_choice)(FIELD *, char *),
     int (* prev_choice)(FIELD *, char *));
FIELDTYPE *link_fieldtype(FIELDTYPE *type1, FIELDTYPE *type2);

DESCRIPTION

new_fieldtype creates a new field type. The application programmer must write the function field_check, which validates the field value, and the function char_check, which validates each character. free_fieldtype frees the space allocated for the field type.

By associating function pointers with a field type, set_fieldtype_arg connects to the field type additional arguments necessary for a set_field_type call. Function mak_arg allocates a structure for the field specific parameters to set_field_type and returns a pointer to the saved data. Function copy_arg duplicates the structure created by make_arg. Function free_arg frees any storage allocated by make_arg or copy_arg.

The form_driver requests REQ_NEXT_CHOICE and REQ_PREV_CHOICE let the user request the next or previous value of a field type comprising an ordered set of values. set_fieldtype_choice allows the application programmer to implement these requests for the given field type. It associates with the given field type those application-defined functions that return pointers to the next or previous choice for the field.

link_fieldtype returns a pointer to the field type built from the two given types. The constituent types may be any application-defined or pre-defined types.

RETURN VALUE

Routines that return pointers always return NULL  on  error.

Routines that return an integer return one of the following:
E_OK           - The function returned successfully.
E_SYSTEM_ERROR - System error.
E_BAD_ARGUMENT - An argument is incorrect.
E_CONNECTED    - Type is connected to one or more fields.

NOTES