X-Git-Url: https://jxself.org/git/?p=mudsync.git;a=blobdiff_plain;f=mudsync%2Fgameobj.scm;h=3957e0a4d40303898888af5828632f9e7f0525cb;hp=921850eef534cde51c23a18a1d9be3a7d91d493c;hb=HEAD;hpb=4736bfc66c4067b0cf9daf8eb69b1fe733d54e00

diff --git a/mudsync/gameobj.scm b/mudsync/gameobj.scm
index 921850e..fbf4a72 100644
--- a/mudsync/gameobj.scm
+++ b/mudsync/gameobj.scm
@@ -1,5 +1,5 @@
 ;;; Mudsync --- Live hackable MUD
-;;; Copyright © 2016 Christopher Allan Webber <cwebber@dustycloud.org>
+;;; Copyright © 2016 Christine Lemmer-Webber <cwebber@dustycloud.org>
 ;;;
 ;;; This file is part of Mudsync.
 ;;;
@@ -21,37 +21,42 @@
 
 (define-module (mudsync gameobj)
   #:use-module (mudsync command)
-  #:use-module (8sync systems actors)
+  #:use-module (mudsync utils)
+  #:use-module (8sync actors)
   #:use-module (8sync agenda)
+  #:use-module (8sync rmeta-slot)
   #:use-module (srfi srfi-1)
+  #:use-module (ice-9 control)
+  #:use-module (ice-9 format)
   #:use-module (ice-9 match)
   #:use-module (oop goops)
   #:export (<gameobj>
-            gameobj-simple-name-f
 
+            create-gameobj
             gameobj-loc
             gameobj-gm
-            gameobj-name
-            gameobj-name-f
+            gameobj-desc
 
-            gameobj-actions))
+            gameobj-act-init
+            gameobj-set-loc!
+            gameobj-occupants
+            gameobj-self-destruct
+
+            slot-ref-maybe-runcheck
+            val-or-run
+
+            build-props
+            dyn-ref
+
+            ;; Some of the more common commands
+            cmd-look-at
+            cmd-take cmd-drop
+            cmd-take-from-no-op cmd-put-in-no-op))
 
 ;;; Gameobj
 ;;; =======
 
-
-;;; Actions supported by all gameobj
-(define gameobj-actions
-  (build-actions
-   (get-commands (wrap-apply gameobj-get-commands))
-   (get-container-commands (wrap-apply gameobj-get-container-commands))
-   (get-occupants (wrap-apply gameobj-get-occupants))
-   (add-occupant! (wrap-apply gameobj-add-occupant!))
-   (remove-occupant! (wrap-apply gameobj-remove-occupant!))
-   (set-loc! (wrap-apply gameobj-set-loc!))
-   (get-name (wrap-apply gameobj-get-name))
-   (get-desc (wrap-apply gameobj-get-desc))
-   ))
+(define build-props build-rmeta-slot)
 
 ;;; *all* game components that talk to players should somehow
 ;;; derive from this class.
@@ -60,49 +65,226 @@
 (define-class <gameobj> (<actor>)
   ;; location id
   (loc #:init-value #f
-       #:accessor gameobj-loc)
+       #:getter gameobj-loc)
   
   ;; Uses a hash table like a set (values ignored)
-  (occupants #:init-thunk make-hash-table
-             #:accessor gameobj-occupants)
+  (occupants #:init-thunk make-hash-table)
 
   ;; game master id
   (gm #:init-keyword #:gm
       #:getter gameobj-gm)
+
   ;; a name to be known by
   (name #:init-keyword #:name
-        #:accessor gameobj-name)
+        #:init-value #f)
+  (goes-by #:init-keyword #:goes-by
+           #:init-value #f)
 
-  (desc #:init-value ""
+  (desc #:init-value #f
         #:init-keyword #:desc)
 
-  ;; how to print our name
-  (name-f #:init-keyword #:name-f
-          #:getter gameobj-name-f
-          #:init-value (wrap gameobj-simple-name-f))
-
-  ;; Name aliases
-  (aliases #:init-keyword #:aliases
-           #:init-value '())
-
+  ;; @@: Maybe commands should be renamed to verbs, I dunno
   ;; Commands we can handle
-  (commands #:init-value '())
+  (commands #:allocation #:each-subclass
+            #:init-thunk (build-commands
+                          (("l" "look") ((direct-command cmd-look-at)))
+                          ("take" ((direct-command cmd-take)
+                                   (prep-indir-command cmd-take-from
+                                                       '("from" "out of"))))
+                          ("put" ((prep-indir-command cmd-put-in
+                                                      '("in" "inside" "into" "on"))))))
 
   ;; Commands we can handle by being something's container
-  (container-commands #:init-value '())
-  (message-handler
-   #:init-value
-   (simple-dispatcher gameobj-actions)))
+  ;;   dominant version (goes before everything)
+  (container-dom-commands #:allocation #:each-subclass
+                          #:init-thunk (build-commands))
+  ;;   subordinate version (goes after everything)
+  (container-sub-commands #:allocation #:each-subclass
+                          #:init-thunk (build-commands))
+
+  ;; Commands we can handle by being contained by something else
+  (contained-commands #:allocation #:each-subclass
+                      #:init-thunk 
+                      (build-commands
+                       (("l" "look") ((direct-command cmd-look-at)))
+                       ("drop" ((direct-command cmd-drop #:obvious? #f)))))
+
+  ;; The extremely squishy concept of "props"... properties!
+  ;; These are flags, etc etc of various types.  This is a hashq table.
+  ;; These have upsides and downsides, but the big upside is that you can
+  ;; query a "prop" of a prospective gameobj without knowing what type of
+  ;; gameobj that is, and not fear some kind of breakage.
+  ;;
+  ;; props by default only have a 'get-prop read-only action handler;
+  ;; any coordination of setting a prop between actors must be
+  ;; added to that actor, to keep things from getting out of control.
+  (props #:init-thunk make-hash-table
+         #:init-keyword #:props)
+  ;; gameobjs may inherit an initial list of these via the
+  ;; initial-props slot, which must always have its
+  ;; #:allocation #:each-subclass and use (build-props) for the
+  ;; #:init-thunk.
+  ;; The vanilla gameobj has no props, on purpose.
+  (initial-props #:allocation #:each-subclass
+                 #:init-thunk (build-props '()))
+
+  ;; Most objects are generally visible by default
+  (invisible? #:init-value #f
+              #:init-keyword #:invisible?)
+  ;; TODO: Fold this into a procedure in invisible? similar
+  ;;   to take-me? and etc
+  (visible-to-player?
+   #:init-value (wrap-apply gameobj-visible-to-player?))
+
+  ;; Can be a boolean or a procedure accepting
+  ;; (gameobj whos-acting #:key from)
+  (take-me? #:init-value #f
+            #:init-keyword #:take-me?)
+  ;; Can be a boolean or a procedure accepting
+  ;; (gameobj whos-acting where)
+  (drop-me? #:init-value #t
+            #:init-keyword #:drop-me?)
+
+  ;; TODO: Remove this and use actor-alive? instead.
+  ;; Set this on self-destruct
+  ;; (checked by some "long running" game routines)
+  (destructed #:init-value #f)
+
+  (actions #:allocation #:each-subclass
+           ;;; Actions supported by all gameobj
+           #:init-thunk
+           (build-actions
+            (init gameobj-act-init)
+            ;; Commands for co-occupants
+            (get-commands gameobj-get-commands)
+            ;; Commands for participants in a room
+            (get-container-dom-commands gameobj-get-container-dom-commands)
+            (get-container-sub-commands gameobj-get-container-sub-commands)
+            ;; Commands for inventory items, etc (occupants of the gameobj commanding)
+            (get-contained-commands gameobj-get-contained-commands)
+
+            (get-occupants gameobj-get-occupants)
+            (add-occupant! gameobj-add-occupant!)
+            (remove-occupant! gameobj-remove-occupant!)
+            (get-loc gameobj-act-get-loc)
+            (set-loc! gameobj-act-set-loc!)
+            (get-name gameobj-get-name)
+            (set-name! gameobj-act-set-name!)
+            (get-desc gameobj-get-desc)
+            (get-prop gameobj-act-get-prop)
+            (goes-by gameobj-act-goes-by)
+            (visible-name gameobj-visible-name)
+            (self-destruct gameobj-act-self-destruct)
+            (tell gameobj-tell-no-op)
+            (assist-replace gameobj-act-assist-replace)
+            (ok-to-drop-here? (lambda (gameobj message . _)
+                                (<-reply message #t))) ; ok to drop by default
+            (ok-to-be-taken-from? gameobj-ok-to-be-taken-from)
+            (ok-to-be-put-in? gameobj-ok-to-be-put-in)
+
+            ;; Common commands
+            (cmd-look-at cmd-look-at)
+            (cmd-take cmd-take)
+            (cmd-drop cmd-drop)
+            (cmd-take-from cmd-take-from-no-op)
+            (cmd-put-in cmd-put-in-no-op))))
 
 
 ;;; gameobj message handlers
 ;;; ========================
 
+;; TODO: This init stuff is a mess, and should be redone now that
+;;   we have the *init* action stuff.  We've really spread out the
+;;   logic for creating a gameobj in several places, eg gm-inject-special!
+(define (create-gameobj class gm loc . args)
+  "Create a gameobj of CLASS with GM and set to location LOC, applying rest of ARGS.
+Note that this doesn't do any special dyn-ref of the location."
+  (let ((new-gameobj (apply create-actor (%current-actor) class
+                            #:gm gm args)))
+    ;; Set the location
+    (<-wait new-gameobj 'set-loc! #:loc loc)
+    ;; Initialize the object
+    (<-wait new-gameobj 'init)))
+
+;; ;; @@: Should we also dyn-ref the loc here?  We can do that, unlike with
+;; ;;   create-gameobj.
+;; ;;   Another route could be to have set-loc! itself know how to use the
+;; ;;   dyn-ref.
+;; (define (gameobj-create-gameobj gameobj class loc . args)
+;;   "Like create-gameobj but saves the step of passing in the gm."
+;;   (apply create-gameobj class (gameobj-gm gameobj) loc args))
+
 ;; Kind of a useful utility, maybe?
 (define (simple-slot-getter slot)
   (lambda (actor message)
-    (reply-message actor message
-                   #:val (slot-ref actor slot))))
+    (<-reply message (slot-ref actor slot))))
+
+(define (gameobj-replace-step-occupants actor occupants)
+  ;; Snarf all the occupants!
+  (display "replacing occupant\n")
+  (when occupants
+    (for-each
+     (lambda (occupant)
+       (<-wait occupant 'set-loc!
+               #:loc (actor-id actor)))
+     occupants)))
+
+(define gameobj-replace-steps*
+  (list gameobj-replace-step-occupants))
+
+(define (run-replacement actor replaces replace-steps)
+  (when replaces
+    (mbody-receive (_ #:key occupants)
+        (<-wait replaces 'assist-replace)
+      (for-each
+       (lambda (replace-step)
+         (replace-step actor occupants))
+       replace-steps))))
+
+(define %nothing (cons '*the* '*nothing*))
+(define (gameobj-setup-props gameobj)
+  (define class (class-of gameobj))
+  (define props (slot-ref gameobj 'props))
+  (maybe-build-rmeta-slot-cache! class 'initial-props
+                                 eq? hashq-set! hashq-ref)
+  ;; Kind of a kludge... we read through the rmeta-slot-cache
+  ;; and use that to build up the table
+  (hash-for-each
+   (lambda (key value)
+     (when (eq? (hashq-ref props key %nothing) ; don't override init'ed instance values
+                %nothing)
+       (hashq-set! props key value)))
+   (rmeta-slot-cache (class-slot-ref class 'initial-props))))
+
+;; TODO: Use the *init* action?
+;;   We could also use a generic method if they didn't have
+;;   what I'm pretty sure is O(n) dispatch in GOOPS...
+(define* (gameobj-act-init actor message #:key replace)
+  "Your most basic game object init procedure."
+  (gameobj-setup-props actor)
+  (run-replacement actor replace gameobj-replace-steps*))
+
+(define* (gameobj-get-prop gameobj key #:optional dflt)
+  (hashq-ref (slot-ref gameobj 'props) key dflt))
+
+(define* (gameobj-set-prop! gameobj key val)
+  (hashq-set! (slot-ref gameobj 'props) key val))
+
+(define* (gameobj-act-get-prop actor message key #:optional dflt)
+  (<-reply message (gameobj-get-prop actor key dflt)))
+
+(define (gameobj-goes-by gameobj)
+  "Find the name we go by.  Defaults to #:name if nothing else provided."
+  (cond ((slot-ref gameobj 'goes-by) =>
+         identity)
+        ((slot-ref gameobj 'name) =>
+         (lambda (name)
+           (list name)))
+        (else '())))
+
+(define (gameobj-act-goes-by actor message)
+  "Reply to a message requesting what we go by."
+  (<-reply message (gameobj-goes-by actor)))
 
 (define (val-or-run val-or-proc)
   "Evaluate if a procedure, or just return otherwise"
@@ -110,58 +292,310 @@
       (val-or-proc)
       val-or-proc))
 
-(define (filter-commands commands verb)
-  (filter
-   (lambda (cmd)
-     (equal? (command-verbs cmd)
-             verb))
-   commands))
-
-(define-mhandler (gameobj-get-commands actor message verb)
-  (define filtered-commands
-    (filter-commands (val-or-run (slot-ref actor 'commands))
-                     verb))
-  (<-reply actor message #:commands filtered-commands))
-
-(define-mhandler (gameobj-get-container-commands actor message verb)
-  (define filtered-commands
-    (filter-commands (val-or-run (slot-ref actor 'container-commands))
-                     verb))
-  (<-reply actor message #:commands filtered-commands))
-
-(define-mhandler (gameobj-add-occupant! actor message who)
+(define (get-candidate-commands actor rmeta-sym verb)
+  (class-rmeta-ref (class-of actor) rmeta-sym verb
+                   #:dflt '()))
+
+(define* (gameobj-get-commands actor message #:key verb)
+  "Get commands a co-occupant of the room might execute for VERB"
+  (define candidate-commands
+    (get-candidate-commands actor 'commands verb))
+  (<-reply message
+           #:commands candidate-commands
+           #:goes-by (gameobj-goes-by actor)))
+
+(define* (gameobj-get-container-dom-commands actor message #:key verb)
+  "Get (dominant) commands as the container / room of message's sender"
+  (define candidate-commands
+    (get-candidate-commands actor 'container-dom-commands verb))
+  (<-reply message #:commands candidate-commands))
+
+(define* (gameobj-get-container-sub-commands actor message #:key verb)
+  "Get (subordinate) commands as the container / room of message's sender"
+  (define candidate-commands
+    (get-candidate-commands actor 'container-sub-commands verb))
+  (<-reply message #:commands candidate-commands))
+
+(define* (gameobj-get-contained-commands actor message #:key verb)
+  "Get commands as being contained (eg inventory) of commanding gameobj"
+  (define candidate-commands
+    (get-candidate-commands actor 'contained-commands verb))
+  (<-reply message
+           #:commands candidate-commands
+           #:goes-by (gameobj-goes-by actor)))
+
+(define* (gameobj-add-occupant! actor message #:key who)
+  "Add an actor to our list of present occupants"
   (hash-set! (slot-ref actor 'occupants)
              who #t))
 
-(define-mhandler (gameobj-remove-occupant! actor message who)
+(define* (gameobj-remove-occupant! actor message #:key who)
+  "Remove an occupant from the room."
   (hash-remove! (slot-ref actor 'occupants) who))
 
-(define-mhandler (gameobj-get-occupants actor message)
+(define* (gameobj-occupants gameobj #:key exclude)
+  (hash-fold
+   (lambda (occupant _ prev)
+     (define exclude-it?
+       (match exclude
+         ;; Empty list and #f are non-exclusion
+         (() #f)
+         (#f #f)
+         ;; A list of addresses... since our address object is (annoyingly)
+         ;; currently a simple cons cell...
+         ((exclude-1 ... exclude-rest)
+          (member occupant exclude))
+         ;; Must be an individual address!
+         (_ (equal? occupant exclude))))
+     (if exclude-it?
+         prev
+         (cons occupant prev)))
+   '()
+   (slot-ref gameobj 'occupants)))
+
+(define* (gameobj-get-occupants actor message #:key exclude)
+  "Get all present occupants of the room."
   (define occupants
-    (hash-map->list (lambda (key val) key)
-                    (gameobj-occupants actor)))
+    (gameobj-occupants actor #:exclude exclude))
+  (<-reply message occupants))
 
-  (<-reply actor message
-           #:occupants occupants))
+(define (gameobj-act-get-loc actor message)
+  (<-reply message (slot-ref actor 'loc)))
 
-;; @@: Should it really be #:id ?  Maybe #:loc-id or #:loc?
-(define-mhandler (gameobj-set-loc! actor message loc)
-  (define old-loc (gameobj-loc actor))
+(define (gameobj-set-loc! gameobj loc)
+  "Set the location of this object."
+  (define old-loc (gameobj-loc gameobj))
   (format #t "DEBUG: Location set to ~s for ~s\n"
-          loc (actor-id-actor actor))
-
-  (set! (gameobj-loc actor) loc)
-  ;; Change registation of where we currently are
-  (if loc
-      (<-wait actor loc 'add-occupant! #:who (actor-id actor)))
-  (if old-loc
-      (<-wait actor old-loc 'remove-occupant! #:who (actor-id actor))))
+          loc (actor-id-actor gameobj))
 
-(define gameobj-get-name (simple-slot-getter 'name))
-(define gameobj-get-desc (simple-slot-getter 'desc))
+  (when (not (equal? old-loc loc))
+    (slot-set! gameobj 'loc loc)
+    ;; Change registation of where we currently are
+    (if old-loc
+        (<-wait old-loc 'remove-occupant! #:who (actor-id gameobj)))
+    (if loc
+        (<-wait loc 'add-occupant! #:who (actor-id gameobj)))))
 
-(define (gameobj-simple-name-f gameobj)
-  "Simplest version: return ourselves for our name."
-  (gameobj-name gameobj))
+;; @@: Should it really be #:id ?  Maybe #:loc-id or #:loc?
+(define* (gameobj-act-set-loc! actor message #:key loc)
+  "Action routine to set the location."
+  (gameobj-set-loc! actor loc))
+
+(define (slot-ref-maybe-runcheck gameobj slot whos-asking . other-args)
+  "Do a slot-ref on gameobj, evaluating it including ourselves
+and whos-asking, and see if we should just return it or run it."
+  (match (slot-ref gameobj slot)
+    ((? procedure? slot-val-proc)
+     (apply slot-val-proc gameobj whos-asking other-args))
+    (anything-else anything-else)))
 
+(define gameobj-get-name (simple-slot-getter 'name))
 
+(define* (gameobj-act-set-name! actor message val)
+  (slot-set! actor 'name val))
+
+(define* (gameobj-desc gameobj #:key whos-looking)
+  (match (slot-ref gameobj 'desc)
+    ((? procedure? desc-proc)
+     (desc-proc gameobj whos-looking))
+    (desc desc)))
+
+(define* (gameobj-get-desc actor message #:key whos-looking)
+  "This is the action equivalent of the gameobj-desc getter"
+  (<-reply message (gameobj-desc actor #:whos-looking whos-looking)))
+
+(define (gameobj-visible-to-player? gameobj whos-looking)
+  "Check to see whether we're visible to the player or not.
+By default, this is whether or not the generally-visible flag is set."
+  (not (slot-ref gameobj 'invisible?)))
+
+(define* (gameobj-visible-name actor message #:key whos-looking)
+  ;; Are we visible?
+  (define we-are-visible
+    ((slot-ref actor 'visible-to-player?) actor whos-looking))
+
+  (define name-to-return
+    (if we-are-visible
+        ;; Return our name
+        (match (slot-ref actor 'name)
+          ((? procedure? name-proc)
+           (name-proc actor whos-looking))
+          ((? string? name)
+           name)
+          (#f #f))
+        #f))
+  (<-reply message #:text name-to-return))
+
+(define (gameobj-self-destruct gameobj)
+  "General gameobj self destruction routine"
+  ;; Unregister from being in any particular room
+  (gameobj-set-loc! gameobj #f)
+  (slot-set! gameobj 'destructed #t)
+  ;; Boom!
+  (self-destruct gameobj))
+
+(define* (gameobj-act-self-destruct gameobj message #:key why)
+  "Action routine for self destruction"
+  (gameobj-self-destruct gameobj))
+
+;; Unless an actor has a tell message, we just ignore it
+(define gameobj-tell-no-op
+  (const 'no-op))
+
+(define (gameobj-replace-data-occupants gameobj)
+  "The general purpose list of replacement data"
+  (list #:occupants (hash-map->list (lambda (occupant _) occupant)
+                                    (slot-ref gameobj 'occupants))))
+
+(define (gameobj-replace-data* gameobj)
+  ;; For now, just call gameobj-replace-data-occupants.
+  ;; But there may be more in the future!
+  (gameobj-replace-data-occupants gameobj))
+
+;; So sad that objects must assist in their replacement ;_;
+;; But that's life in a live hacked game!
+(define (gameobj-act-assist-replace gameobj message)
+  "Vanilla method for assisting in self-replacement for live hacking"
+  (apply <-reply message
+         (gameobj-replace-data* gameobj)))
+
+(define (gameobj-ok-to-be-taken-from gameobj message whos-acting)
+  (call-with-values (lambda ()
+                      (slot-ref-maybe-runcheck gameobj 'take-me?
+                                               whos-acting #:from #t))
+    ;; This allows this to reply with #:why-not if appropriate
+    (lambda args
+      (apply <-reply message args))))
+
+(define (gameobj-ok-to-be-put-in gameobj message whos-acting where)
+  (call-with-values (lambda ()
+                      (slot-ref-maybe-runcheck gameobj 'drop-me?
+                                               whos-acting where))
+    ;; This allows this to reply with #:why-not if appropriate
+    (lambda args
+      (apply <-reply message args))))
+
+
+;;; Utilities every gameobj has
+;;; ---------------------------
+
+(define (dyn-ref gameobj special-symbol)
+  "Dynamically look up a special object from the gm"
+  (match special-symbol
+    ;; if it's a symbol, look it up dynamically
+    ((? symbol? _)
+     ;; TODO: If we get back an #f at this point, should we throw
+     ;;   an error?  Obviously #f is okay, but maybe not if 
+     (mbody-val (<-wait (slot-ref gameobj 'gm) 'lookup-special
+                        #:symbol special-symbol)))
+    ;; if it's false, return nothing
+    (#f #f)
+    ;; otherwise it's probably an address, return it as-is
+    (_ special-symbol)))
+
+
+
+;;; Basic actions
+;;; -------------
+
+(define %formless-desc
+  "You don't see anything special.")
+
+(define* (cmd-look-at gameobj message
+                      #:key direct-obj
+                      (player (message-from message)))
+  (let ((desc
+         (or (gameobj-desc gameobj #:whos-looking player)
+             %formless-desc)))
+    (<- player 'tell #:text desc)))
+
+(define* (cmd-take gameobj message
+                   #:key direct-obj
+                   (player (message-from message)))
+  (define player-name
+    (mbody-val (<-wait player 'get-name)))
+  (define player-loc
+    (mbody-val (<-wait player 'get-loc)))
+  (define our-name (slot-ref gameobj 'name))
+  (define self-should-take
+    (slot-ref-maybe-runcheck gameobj 'take-me? player))
+  ;; @@: Is there any reason to allow the room to object in the way
+  ;;   that there is for dropping?  It doesn't seem like it.
+  (call-with-values (lambda ()
+                      (slot-ref-maybe-runcheck gameobj 'take-me? player))
+    (lambda* (self-should-take #:key (why-not
+                                      `("It doesn't seem like you can take "
+                                        ,our-name ".")))
+      (if self-should-take
+          ;; Set the location to whoever's picking us up
+          (begin
+            (gameobj-set-loc! gameobj player)
+            (<- player 'tell
+                #:text (format #f "You pick up ~a.\n"
+                               our-name))
+            (<- player-loc 'tell-room
+                #:text (format #f "~a picks up ~a.\n"
+                               player-name
+                               our-name)
+                #:exclude player))
+          (<- player 'tell #:text why-not)))))
+
+(define* (cmd-drop gameobj message
+                   #:key direct-obj
+                   (player (message-from message)))
+  (define player-name
+    (mbody-val (<-wait player 'get-name)))
+  (define player-loc
+    (mbody-val (<-wait player 'get-loc)))
+  (define our-name (slot-ref gameobj 'name))
+  (define should-drop
+    (slot-ref-maybe-runcheck gameobj 'drop-me? player))
+  (define (room-objection-to-drop)
+    (mbody-receive (_ drop-ok? #:key why-not) ; does the room object to dropping?
+        (<-wait player-loc 'ok-to-drop-here? player (actor-id gameobj))
+      (and (not drop-ok?)
+           ;; Either give the specified reason, or give a boilerplate one
+           (or why-not
+               `("You'd love to drop " ,our-name
+                 " but for some reason it doesn't seem like you can"
+                 " do that here.")))))
+  (cond
+   ((not player-loc)
+    (<- player 'tell
+        #:text `("It doesn't seem like you can drop " ,our-name 
+                " here, because you don't seem to be anywhere?!?")))
+   ;; TODO: Let ourselves supply a reason why not.
+   ((not should-drop)
+    (<- player 'tell
+        #:text (format #f "It doesn't seem like you can drop ~a.\n"
+                       our-name)))
+   ((room-objection-to-drop)
+    (<- player 'tell
+        #:text room-objection-to-drop))
+   (else
+    (gameobj-set-loc! gameobj player-loc)
+    ;; TODO: Allow more flavortext here.
+    (<- player 'tell
+        #:text (format #f "You drop ~a.\n"
+                       our-name))
+    (<- player-loc 'tell-room
+        #:text (format #f "~a drops ~a.\n"
+                       player-name
+                       our-name)
+        #:exclude player))))
+
+(define* (cmd-take-from-no-op gameobj message
+                              #:key direct-obj indir-obj preposition
+                              (player (message-from message)))
+  (<- player 'tell
+      #:text `("It doesn't seem like you can take anything "
+               ,preposition " "
+               ,(slot-ref gameobj 'name) ".")))
+
+(define* (cmd-put-in-no-op gameobj message
+                           #:key direct-obj indir-obj preposition
+                           (player (message-from message)))
+  (<- player 'tell
+      #:text `("It doesn't seem like you can put anything "
+               ,preposition " "
+               ,(slot-ref gameobj 'name) ".")))