cron.before and cron.after now return a clock

cron.lua

@@ -28,8 +28,6 @@ local cron = {
 
 -- Private functions
 
-local entries --  initialized in cron.reset
-
 local function isCallable(callback)
   local tc = type(callback)
   if tc == 'function' then return true end
@@ -40,67 +38,61 @@ local function isCallable(callback)
   return false
 end
 
-local function checkTimeAndCallback(time, callback)
+local function checkPositiveInteger(name, value)
-  assert(type(time) == "number" and time > 0, "time must be a positive number")
+  if type(value) ~= "number" or value < 0 then
-  assert(isCallable(callback), "callback must be a function")
+    error(name .. " must be a positive number")
+  end
 end
 
-local function newEntry(time, callback, update, ...)
+local Clock = {}
-  local entry = {
+local Clock_mt = {__index = Clock}
+
+local function newClock(time, callback, update, ...)
+  checkPositiveInteger('time', time)
+  assert(isCallable(callback), "callback must be a function")
+
+  return setmetatable({
     time     = time,
     callback = callback,
     args     = {...},
     running  = 0,
     update   = update
-  }
+  }, Clock_mt)
-  entries[entry] = entry
-  return entry
 end
 
-local function updateTimedEntry(self, dt) -- returns true if expired
+local function updateAfterClock(self, dt) -- returns true if expired
+  checkPositiveInteger('dt', dt)
+
+  if self.running >= self.time then return true end
+
   self.running = self.running + dt
+
   if self.running >= self.time then
     self.callback(unpack(self.args))
-    cron.cancel(self)
+    return true
   end
+  return false
 end
 
-local function updatePeriodicEntry(self, dt)
+local function updateEveryClock(self, dt)
+  checkPositiveInteger('dt', dt)
+
   self.running = self.running + dt
 
   while self.running >= self.time do
     self.callback(unpack(self.args))
     self.running = self.running - self.time
   end
-end
+  return false
-
--- Public functions
-
-function cron.cancel(id)
-  entries[id] = nil
 end
 
 function cron.after(time, callback, ...)
-  checkTimeAndCallback(time, callback)
+  return newClock(time, callback, updateAfterClock, ...)
-  return newEntry(time, callback, updateTimedEntry, ...)
 end
 
 function cron.every(time, callback, ...)
-  checkTimeAndCallback(time, callback)
+  return newClock(time, callback, updateEveryClock, ...)
-  return newEntry(time, callback, updatePeriodicEntry, ...)
 end
 
-function cron.update(dt)
-  assert(type(dt) == "number" and dt >= 0, "dt must be a non-negative number")
-
-  for _, entry in pairs(entries) do entry:update(dt) end
-end
-
-function cron.reset()
-  entries = {}
-end
-
-cron.reset()
-
 return cron
 

spec/cron_spec.lua

@@ -2,7 +2,7 @@ local cron = require 'cron'
 
 describe( 'cron', function()
 
-  local counter = 0
+  local counter
   local function count(amount)
     amount = amount or 1
     counter = counter + amount
@@ -11,41 +11,25 @@ describe( 'cron', function()
 
   before_each(function()
     counter = 0
-    cron.reset()
   end)
 
-  describe('.update', function()
+
+  describe('clock', function()
+
+    describe(':update', function()
       it('throws an error if dt is a negative number', function()
-      assert.error(function() cron.update() end)
+        local clock = cron.every(1, count)
-      assert.error(function() cron.update(-1) end)
+        assert.error(function() clock:update() end)
-      assert.not_error(function() cron.update(1) end)
+        assert.error(function() clock:update(-1) end)
+        assert.not_error(function() clock:update(1) end)
       end)
     end)
 
-  describe('.reset', function()
-    it('Cancels all timed actions', function()
-      cron.after(1, count)
-      cron.after(2, count)
-      cron.update(1)
-      assert.equal(counter, 1)
-      cron.reset()
-      cron.update(1)
-      assert.equal(counter, 1)
   end)
 
-    it('Cancels all periodical actions', function()
-      cron.every(1, count)
-      cron.update(1)
-      assert.equal(counter, 1)
-      cron.reset()
-      cron.update(1)
-      assert.equal(counter, 1)
-    end)
-
-  end)
 
   describe('.after', function()
-    it('Throws error if time is not a positive number, or callback is not callable', function()
+    it('checks parameters', function()
       assert.error(function() cron.after('error', count) end)
       assert.error(function() cron.after(2, 'error') end)
       assert.error(function() cron.after(-2, count) end)
@@ -54,28 +38,45 @@ describe( 'cron', function()
       assert.not_error(function() cron.after(2, countable) end)
     end)
 
-    it('Executes timed actions only once, at the right time', function()
+    it('produces a clock that executes actions only once, at the right time', function()
-      cron.after(2, count)
+      local c1 = cron.after(2, count)
-      cron.after(4, count)
+      local c2 = cron.after(4, count)
-      cron.update(1)
+
+      -- 1
+      c1:update(1)
       assert.equal(counter, 0)
-      cron.update(1)
+      c2:update(1)
+      assert.equal(counter, 0)
+
+      -- 2
+      c1:update(1)
       assert.equal(counter, 1)
-      cron.update(1)
+      c2:update(1)
       assert.equal(counter, 1)
-      cron.update(1)
+
+      -- 3
+      c1:update(1)
+      assert.equal(counter, 1)
+      c2:update(1)
+      assert.equal(counter, 1)
+
+      -- 4
+      c1:update(1)
+      assert.equal(counter, 1)
+      c2:update(1)
       assert.equal(counter, 2)
+
     end)
 
-    it('Passes on parameters to the function, if specified', function()
+    it('Passes on parameters to the callback', function()
-      cron.after(1, count, 2)
+      local c1 = cron.after(1, count, 2)
-      cron.update(1)
+      c1:update(1)
       assert.equal(counter, 2)
     end)
   end)
 
   describe('.every', function()
-    it('Throws errors if time is not a positive number, or callback is not function', function()
+    it('checks parameters', function()
       assert.error(function() cron.every('error', count) end)
       assert.error(function() cron.every(2, 'error') end)
       assert.error(function() cron.every(-2, count) end)
@@ -84,49 +85,33 @@ describe( 'cron', function()
       assert.not_error(function() cron.every(2, countable) end)
     end)
 
-    it('Executes periodical actions periodically', function()
+    it('Invokes callback periodically', function()
-      cron.every(3, count)
+      local c = cron.every(3, count)
-      cron.update(1)
+
+      c:update(1)
       assert.equal(counter, 0)
-      cron.update(2)
+
+      c:update(2)
       assert.equal(counter, 1)
-      cron.update(2)
+
+      c:update(2)
       assert.equal(counter, 1)
-      cron.update(1)
+
+      c:update(1)
       assert.equal(counter, 2)
     end)
 
     it('Executes the same action multiple times on a single update if appropiate', function()
-      cron.every(1, count)
+      local c = cron.every(1, count)
-      cron.update(2)
+      c:update(2)
       assert.equal(counter, 2)
     end)
 
     it('Respects parameters', function()
-      cron.every(1, count, 2)
+      local c = cron.every(1, count, 2)
-      cron.update(2)
+      c:update(2)
       assert.equal(counter, 4)
     end)
   end)
 
-  describe('.cancel', function()
-    it('Cancels timed entries', function()
-      local id = cron.after(1, count)
-      cron.update(1)
-      assert.equal(counter, 1)
-      cron.cancel(id)
-      cron.update(1)
-      assert.equal(counter, 1)
-    end)
-
-    it('Cancels periodical entries', function()
-      local id = cron.every(1, count)
-      cron.update(1)
-      assert.equal(counter, 1)
-      cron.cancel(id)
-      cron.update(1)
-      assert.equal(counter, 1)
-    end)
-  end)
-
 end)