5. Control File Format

The Forms mode control file serves two purposes. First, it names the data file to use, and defines its format and properties. Second, the Emacs buffer it occupies is used by Forms mode to display the forms.

The contents of the control file are evaluated as a Lisp program. It should set the following Lisp variables to suitable values:

forms-file

This variable specifies the name of the data file. Example:

(setq forms-file "my/data-file")

forms-format-list

This variable describes the way the fields of the record are formatted on the screen. For details, see 6. The Format Description.

forms-number-of-fields

This variable holds the number of fields in each record of the data file. Example:

(setq forms-number-of-fields 10)

If the control file doesn't set all of these variables, Forms mode reports an error.

The control file can optionally set the following additional Forms mode variables. Most of them have default values that are good for most applications.

forms-field-sep

This variable may be used to designate the string which separates the fields in the records of the data file. If not set, it defaults to the string "\t" (a tab character). Example:

(setq forms-field-sep "\t")

forms-read-only

If the value is non-nil, the data file is treated read-only. (Forms mode also treats the data file as read-only if you don't have access to write it.) Example:

(set forms-read-only t)

forms-multi-line

This variable specifies the pseudo newline separator that allows multi-line fields. This separator goes between the "lines" within a field--thus, the field doesn't really contain multiple lines, but it appears that way when displayed in Forms mode. If the value is nil, multi-line text fields are prohibited. The pseudo newline must not be a character contained in forms-field-sep.

The default value is "\^k", so the default pseudo newline is the character control-k. Example:

(setq forms-multi-line "\^k")

forms-new-record-filter

This variable holds a function to be called whenever a new record is created to supply default values for fields. If it is nil, no function is called. See section 7. Modifying The Forms Contents, for details.

forms-modified-record-filter

This variable holds a function to be called whenever a record is modified, just before updating the Forms data file. If it is nil, no function is called. See section 7. Modifying The Forms Contents, for details.