Control File Format Top Modifying Forms Contents
forms-format-list specifies the format of the data
in the data file, and how to convert the data for display in Forms mode.
Its value must be a list of Forms mode formatting elements, each
of which can be a string, a number, a Lisp list, or a Lisp symbol that
evaluates to one of those. The formatting elements are processed in the
order they appear in the list.
A string formatting element is inserted in the forms ``as is,'' as text that the user cannot alter.
A number element selects a field of the record. The contents of this field are inserted in the display at this point. Field numbers count starting from 1 (one).
A formatting element that is a list specifies a function call. This function is called every time a record is displayed, and its result, which must be a string, is inserted in the display text. The function should do nothing but returning a string.
The function you call can access the fields of the record as a list in
A symbol used as a formatting element should evaluate to a string, number, or list; the value is interpreted as a formatting element, as described above.
If a record does not contain the number of fields as specified in
forms-number-of-fields, a warning message will be printed. Excess
fields are ignored, missing fields are set to empty.
The control file which displays `
/etc/passwd' file as demonstrated
in the beginning of this manual might look as follows:
;; This demo visits `
/etc/passwd'. (setq forms-file "/etc/passwd") (setq forms-number-of-fields 7) (setq forms-read-only t) ; to make sure (setq forms-field-sep ":") ;; Don't allow multi-line fields. (setq forms-multi-line nil) (setq forms-format-list (list "====== /etc/passwd ======\n\n" "User : " 1 " Uid: " 3 " Gid: " 4 "\n\n" "Name : " 5 "\n\n" "Home : " 6 "\n\n" "Shell: " 7 "\n"))
When you construct the value of
forms-format-list, you should
usually either quote the whole value, like this,
(setq forms-format-list '( "====== " forms-file " ======\n\n" "User : " 1 (make-string 20 ?-) ... ))
or quote the elements which are lists, like this:
(setq forms-format-list (list "====== " forms-file " ======\n\n" "User : " 1 '(make-string 20 ?-) ... ))
Forms mode validates the contents of
forms-format-list when you
visit a database. If there are errors, processing is aborted with an
error message which includes a descriptive text. See Error Messages,
for a detailed list of error messages.
forms-format-list is specified, Forms mode will supply a
default format list. This list contains the name of the file being
visited, and a simple label for each field indicating the field number.