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As soon as a helper function grows, move it into a small library file. That keeps the plug-in focused and makes the helper reusable across multiple plug-ins.

Make a Library Function

We can take the send-message function and make a new file with that as its content. Save the file into your repo folder, not the plugins part, perhaps near the top level;

/home/your-username/code/
  ├── scheme/
      ├── library/
      │     └── send-message.scm
      └── plug-ins/
            └── hello-world/
                  └── hello-world.scm

scheme/: This is your main directory for storing your Scheme code.
- library/: This is where shared functions like send-message.scm live.
- plug-ins/: This is where your individual plug-ins are stored.
  - hello-world/: A folder for the specific “Hello World!” plug-in.
    - hello-world.scm: The script file for the plug-in.

Example of a library function send-message.scm

;; Function to handle message output to various destinations
(define (send-message message output)
  (cond
    ;; Send to the Error Console
    ((eq? output 'error-console)
       ;; Set the handler to Error Console
       (lumi-message-set-handler 2)
       (lumi-message message))

    ;; Send to the GUI dialog box
    ((eq? output 'gui)
       ;; Set the handler to GUI dialog
       (lumi-message-set-handler 0)
       (lumi-message message))

    ;; Send to the terminal window
    ((eq? output 'terminal)
       ;; Terminal output is handled with display
       (display message)))

  ;; Restore the default message handler to the Error Console
  (lumi-message-set-handler 2))

Load the Library Function

We can load that library function with the Scheme load command;

Loading a library file:

#!/usr/bin/env lumi-scheme-interpreter-0.1

(load "/home/mark/code/github/script-plugins/funky-library/send-message.scm")

(define (scheme-hello-world)
  (let ((message "Hello world!\n"))
    (send-message message 'gui)
    (send-message message 'error-console)
    (send-message message 'terminal)))

(scheme-register-procedure "scheme-hello-world"
  "Hello world!"
  "A Scheme procedure plug-in refactored"
  "Mark Sweeney"
  "Under GNU GENERAL PUBLIC LICENSE Version 3"
  "2024")

(scheme-menu-register
  "scheme-hello-world"
  "<Image>/Funky")

Hey! We’ve now got something simpler and shorter to read, that kind of describes itself without comments. This is the satisfying conclusion of refactoring.

Refactoring Validation