Observerable/observer-ish pattern for Lua markers

A new framework for Lua markers, similar to the observable/observer
design pattern, which decouples the thing being activated from the thing
watching for the activating condition.  This makes it easier to create
new types of Lua markers which are triggered by dungeon events, and
easier to add new triggering conditions to already existing marker
types.  Currently only ChangeFlags (clua/lm_flags.lua) and
MonsterOnTrigger (clua/lm_monst.lua) use it.

1 files changed, 73 insertions, 62 deletions

diff --git a/crawl-ref/source/dat/clua/lm_monst.lua b/crawl-ref/source/dat/clua/lm_monst.lua
index f26e73e89b..539b7b140b 100644
--- a/crawl-ref/source/dat/clua/lm_monst.lua
+++ b/crawl-ref/source/dat/clua/lm_monst.lua
@@ -3,11 +3,12 @@
 -- Create a monster on certain events
 --------------------------------------------------------------------------
 
---------------------------------------------------------------------------------------
--- This marker creates a monster on certain events.  It uses the following parameters:
+-------------------------------------------------------------------------------
+-- This marker creates a monster on certain events.  It uses the following
+-- parameters:
 --
--- * death_monster: The name of the monster who's death triggers the creation of
---       the new monster.
+-- * death_monster: The name of the monster who's death triggers the creation
+--       of the new monster.
 --
 -- * new_monster: The name of the monster to create.
 --
@@ -20,30 +21,21 @@
 --
 -- NOTE: If the feature where the marker is isn't habitable by the new monster,
 -- the feature will be changed to the monster's primary habitat.
---------------------------------------------------------------------------------------
+-------------------------------------------------------------------------------
 
 -- TODO:
 --  * Place more than one monster.
 --  * Place monster displaced from marker.
+--  * Be triggered more than once.
 
-MonsterOnTrigger = { CLASS = "MonsterOnTrigger" }
-MonsterOnTrigger.__index = MonsterOnTrigger
+require('clua/lm_trig.lua')
 
-function MonsterOnTrigger:_new()
-  local pm = { }
-  setmetatable(pm, self)
-  self.__index = self
-
-  return pm
-end
+MonsterOnTrigger       = util.subclass(Triggerable)
+MonsterOnTrigger.CLASS = "MonsterOnTrigger"
 
 function MonsterOnTrigger:new(pars)
   pars = pars or { }
 
-  if not pars.death_monster or pars.death_monster == "" then
-    error("Must provide death_monster")
-  end
-
   if not pars.new_monster or pars.new_monster == "" then
     error("Must provide new_monster")
   end
@@ -51,14 +43,15 @@ function MonsterOnTrigger:new(pars)
   pars.message_seen   = pars.message_seen or pars.message or ""
   pars.message_unseen = pars.message_unseen or pars.message or ""
 
-  local pm = self:_new()
-  pm.message_seen    = pars.message_seen
-  pm.message_unseen  = pars.message_unseen
-  pm.death_monster   = pars.death_monster
-  pm.new_monster     = pars.new_monster
-  pm.props           = pars
+  local mot = self.super.new(self)
 
-  return pm
+  mot.message_seen    = pars.message_seen
+  mot.message_unseen  = pars.message_unseen
+  mot.death_monster   = pars.death_monster
+  mot.new_monster     = pars.new_monster
+  mot.props           = pars
+
+  return mot
 end
 
 function MonsterOnTrigger:property(marker, pname)
@@ -66,53 +59,71 @@ function MonsterOnTrigger:property(marker, pname)
 end
 
 function MonsterOnTrigger:write(marker, th)
-  lmark.marshall_table(th, self)
+  MonsterOnTrigger.super.write(self, marker, th)
+
+  file.marshall(th, self.message_seen)
+  file.marshall(th, self.message_unseen)
+  file.marshall(th, self.new_monster)
+  lmark.marshall_table(th, self.props)
 end
 
 function MonsterOnTrigger:read(marker, th)
-  return MonsterOnTrigger:new(lmark.unmarshall_table(th))
-end
+  MonsterOnTrigger.super.read(self, marker, th)
+
+  self.message_seen   = file.unmarshall_string(th)
+  self.message_unseen = file.unmarshall_string(th)
+  self.new_monster    = file.unmarshall_string(th)
+  self.props          = lmark.unmarshall_table(th)
 
-function MonsterOnTrigger:activate(marker)
-  dgn.register_listener(dgn.dgn_event_type('monster_dies'), marker)
+  setmetatable(self, MonsterOnTrigger) 
+
+  return self
 end
 
-function MonsterOnTrigger:event(marker, ev)
-  local midx = ev:arg1()
-  local mons = dgn.mons_from_index(midx)
+function MonsterOnTrigger:on_trigger(triggerer, marker, ev)
+  local x,     y     = marker:pos()
+  local you_x, you_y = you.pos()
+
+  if x == you_x and y == you_y then
+    return
+  end
 
-  if not mons then
-    error("MonsterOnTrigger:event() didn't get a valid monster index")
+  if dgn.mons_at(x, y) then
+    return
   end
 
-  if mons.name == self.death_monster then
-    local x,     y     = marker:pos()
-    local you_x, you_y = you.pos()
-
-    if x == you_x and y == you_y then
-      return
-    end
-
-    -- you.losight() seems to be necessary if the player has been moved by
-    -- a wizard command and then the marker triggered by another wizard
-    -- command, since then no turns will have been taken and the LOS info
-    -- won't have been updated.
-    you.losight()
-    local see_cell = you.see_cell(x, y)
-
-    if (not dgn.create_monster(x, y, self.new_monster)) then
-      return
-    elseif self.message_seen ~= "" and see_cell then
-      crawl.mpr(self.message_seen)
-    elseif self.message_unseen ~= "" and not see_cell then
-      crawl.mpr(self.message_unseen)
-    end
-
-    dgn.remove_listener(marker)
-    dgn.remove_marker(marker)
+  -- you.losight() seems to be necessary if the player has been moved by
+  -- a wizard command and then the marker triggered by another wizard
+  -- command, since then no turns will have been taken and the LOS info
+  -- won't have been updated.
+  you.losight()
+  local see_cell = you.see_cell(x, y)
+
+  if (not dgn.create_monster(x, y, self.new_monster)) then
+    return
+  elseif self.message_seen ~= "" and see_cell then
+    crawl.mpr(self.message_seen)
+  elseif self.message_unseen ~= "" and not see_cell then
+    crawl.mpr(self.message_unseen)
   end
+
+  self:remove(marker)
 end
 
-function monster_on_trigger(pars)
-  return MonsterOnTrigger:new(pars)
+function monster_on_death(pars)
+  local death_monster = pars.death_monster or pars.target
+
+  pars.death_monster = nil
+  pars.target        = nil
+
+  local mod = MonsterOnTrigger:new(pars)
+
+  mod:add_triggerer(
+                     DgnTriggerer:new {
+                       type   = "monster_dies",
+                       target = death_monster
+                     }
+                   )
+
+  return mod
 end