Refactored the hooks chain

 This new implementation freezes the chain when the bot is frozen, and
 supports multiple chains, without the need to reimplement the logic
 everytime you add a new chain.

Author: Pietro Albini

botogram/bot.py

@@ -54,7 +54,7 @@ def __init__(self, api_connection):
         self._shared_memory = shared.SharedMemory()
 
         # Register bot's shared memory initializers
-        inits = self._main_component._get_memory_preparers()
+        inits = self._main_component._get_chains()["memory_preparers"][0]
         maincompid = self._main_component._component_id
         self._shared_memory.register_preparers_list(maincompid, inits)
 
@@ -162,12 +162,13 @@ def use(self, *components, only_init=False):
                 self._components.append(component)
 
             # Register initializers for the shared memory
+            chains = component._get_chains()
             compid = component._component_id
-            preparers = component._get_memory_preparers()
+            preparers = chains["memory_preparers"][0]
             self._shared_memory.register_preparers_list(compid, preparers)
 
             # Register tasks
-            self._scheduler.register_tasks_list(component._get_timers())
+            self._scheduler.register_tasks_list(chains["tasks"][0])
 
     def process(self, update):
         """Process an update object"""
@@ -184,12 +185,14 @@ def run(self, workers=2):
 
     def freeze(self):
         """Return a frozen instance of the bot"""
+        chains = components.merge_chains(self._main_component,
+                                         *self._components)
+
         return frozenbot.FrozenBot(self.api, self.about, self.owner,
                                    self.hide_commands, self.before_help,
                                    self.after_help, self.process_backlog,
                                    self.lang, self.itself, self._commands_re,
-                                   self._components+[self._main_component],
-                                   self._scheduler,
+                                   chains, self._scheduler,
                                    self._main_component._component_id,
                                    self._bot_id, self._shared_memory)
 

botogram/components.py

@@ -144,23 +144,49 @@ def _add_no_commands_hook(self, func):
         hook = hooks.NoCommandsHook(func, self)
         self.__no_commands.append(hook)
 
-    def _get_hooks_chain(self):
+    def _get_chains(self):
         """Get the full hooks chain for this component"""
-        return [
+        messages = [
             self.__before_processors[:],
             [self.__commands[name] for name in sorted(self.__commands.keys())],
             self.__no_commands[:],
             self.__processors[:],
         ]
+        return {
+            "messages": messages,
+            "memory_preparers": [self.__memory_preparers],
+            "tasks": [self.__timers],
+        }
 
     def _get_commands(self):
         """Get all the commands this component implements"""
         return self.__commands
 
-    def _get_memory_preparers(self):
-        """Get a list of all the shared memory initializers"""
-        return self.__memory_preparers
 
-    def _get_timers(self):
-        """Get a list of all the timers"""
-        return self.__timers
+def merge_chains(main, *components):
+    """Merge multiple chains returned by the components"""
+    merged = {}
+    components = [main]+list(reversed(components))
+
+    # First of all, merge all the subchains of the different components
+    # together -- This is a separate step so the order is preserved
+    for component in components:
+        macrochains = component._get_chains()
+        for kind, chains in macrochains.items():
+            if kind not in merged:
+                merged[kind] = []
+
+            for i, chain in enumerate(chains):
+                try:
+                    merged[kind][i] += chain
+                except IndexError:
+                    merged[kind].append(chain[:])
+
+    # Then merge all the subchains together
+    result = {}
+    for kind, chains in merged.items():
+        result[kind] = []
+        for chain in chains:
+            result[kind] += chain
+
+    return result

botogram/frozenbot.py

@@ -22,7 +22,7 @@ class FrozenBot:
 
     def __init__(self, api, about, owner, hide_commands, before_help,
                  after_help, process_backlog, lang, itself, commands_re,
-                 components, scheduler, main_component_id, bot_id,
+                 chains, scheduler, main_component_id, bot_id,
                  shared_memory):
         # This attribute should be added with the default setattr, because is
         # needed by the custom setattr
@@ -38,25 +38,11 @@ def __init__(self, api, about, owner, hide_commands, before_help,
         self.process_backlog = process_backlog
         self.lang = lang
         self._commands_re = commands_re
-        self._components = components
         self._main_component_id = main_component_id
         self._bot_id = bot_id
         self._shared_memory = shared_memory
         self._scheduler = scheduler
-
-        # Rebuild the hooks chain and commands list
-        self._commands = components[-1]._get_commands()
-        self._chain = []
-        chains = components[-1]._get_hooks_chain()
-        for component in reversed(components[:-1]):
-            self._commands.update(component._get_commands())
-
-            comp_chain = component._get_hooks_chain()
-            for i in range(len(chains)):
-                chains[i] += comp_chain[i]
-
-        for chain in chains:
-            self._chain += chain
+        self._chains = chains
 
         # Setup the logger
         self.logger = logbook.Logger('botogram bot')
@@ -75,7 +61,7 @@ def __reduce__(self):
         args = (
             self.api, self.about, self.owner, self.hide_commands,
             self.before_help, self.after_help, self.process_backlog,
-            self.lang, self.itself, self._commands_re, self._components,
+            self.lang, self.itself, self._commands_re, self._chains,
             self._scheduler, self._main_component_id, self._bot_id,
             self._shared_memory,
         )
@@ -186,7 +172,7 @@ def process(self, update):
 
         update.set_api(self.api)  # Be sure to use the correct API object
 
-        for hook in self._chain:
+        for hook in self._chains["messages"]:
             # Get the correct name of the hook
             name = hook.name
             self.logger.debug("Processing update #%s with the %s hook..." %