Push sketch slightly further up hill.

plugins/incremental.lisp

 
 (defpackage :coleslaw-incremental
   (:use :cl)
-  (:import-from :coleslaw #:get-updated-files
+  (:import-from :alexandria #:when-let)
+  (:import-from :coleslaw #:all-subclasses
+                          #:content
+                          #:construct
+                          #:get-updated-files
                           #:find-content-by-path
-                          #:write-document)
+                          #:write-document
+                          #:rel-path)
   (:export #:enable))
 
 (in-package :coleslaw-incremental)
 
 ;; FIXME: We currently never update the site for config changes.
 ;; Examples to consider include changing the theme or domain of the site.
+;; Both would require full site recompiles. Consequently, it seems reasonable
+;; to expect that incremental plugin users:
+;;   A) have done a full build of their site
+;;   B) have a cl-store dump of the database at ~/.coleslaw.db
+;;      ^ we should provide a script or plugin just for this
 
 ;; NOTE: We're gonna be a bit dirty here and monkey patch. The compilation model
 ;; still isn't an "exposed" part of Coleslaw. After some experimentation maybe
   "A list of changed content instances to iterate over and write out to disk.")
 
 (defun coleslaw::load-content ()
-  ;; TODO: What if the file doesn't exist?
   (let ((db-file (rel-path (user-homedir-pathname) ".coleslaw.db")))
     (setf coleslaw::*site* (cl-store:restore db-file))
     (loop for (status path) in (get-updated-files)
         ((string= "M" status) (process-change :modified path))
         ((string= "A" status) (process-change :added path))))
 
-(defgeneric process-change (status path)
-  (:documentation "Updates the database as needed for the STATUS change to PATH."))
+(defgeneric process-change (status path &key &allow-other-keys)
+  (:documentation "Updates the database as needed for the STATUS change to PATH.")
+  (:method :around (status path &key)
+    (let ((extension (pathname-type path))
+          (ctypes (all-subclasses (find-class 'content))))
+      ;; This feels way too clever. I wish I could think of a better option.
+      (flet ((class-name-p (x class)
+               (string-equal x (symbol-name (class-name class)))))
+        (when-let (ctype (find extension ctypes :test #'class-name-p))
+          (call-next-method status path :ctype ctype))))))
+
+(defmethod process-change ((status (eql :deleted)) path &key)
+  (let ((obj (find-content-by-path path)))
+    ))
+
+(defmethod process-change ((status (eql :modified)) path &key)
+  (let ((obj (find-content-by-path path)))
+    ))
+
+(defmethod process-change ((status (eql :added)) path &key ctype)
+  (let ((obj (construct ctype (read-content path))))
+    ))
 
 (defun coleslaw::compile-blog (staging)
   "lulz. Do it live. DO IT ALL LIVE."

src/util.lisp

   "Create an instance of CLASS-NAME with the given ARGS."
   (apply 'make-instance class-name args))
 
+;; Thanks to bknr-web for this bit of code.
+(defun all-subclasses (class)
+  "Return a list of all the subclasses of CLASS."
+  (let ((subclasses (closer-mop:class-direct-subclasses class)))
+    (append subclasses (loop for subclass in subclasses
+                          nconc (all-subclasses subclass)))))
+
 (defmacro do-subclasses ((var class) &body body)
   "Iterate over the subclasses of CLASS performing BODY with VAR
 lexically bound to the current subclass."
-  (alexandria:with-gensyms (klasses all-subclasses)
-    `(labels ((,all-subclasses (class)
-                (let ((subclasses (closer-mop:class-direct-subclasses class)))
-                  (append subclasses (loop for subclass in subclasses
-                                        nconc (,all-subclasses subclass))))))
-       (let ((,klasses (,all-subclasses (find-class ',class))))
-         (loop for ,var in ,klasses do ,@body)))))
+  (alexandria:with-gensyms (klasses)
+    `(let ((,klasses (all-subclasses (find-class ',class))))
+       (loop for ,var in ,klasses do ,@body))))
 
 (defmacro do-files ((var path &optional extension) &body body)
   "For each file under PATH, run BODY. If EXTENSION is provided, only run