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diff --git a/docs/write_hooks.rst b/docs/write_hooks.rst new file mode 100644 index 000000000..ffc41d705 --- /dev/null +++ b/docs/write_hooks.rst @@ -0,0 +1,162 @@ +.. _write_hooks: + +Hooks +===== + +A Hook is a python file which is located at :file:`module/plugins/hooks`. +The :class:`HookManager <module.HookManager.HookManager>` will load it automatically on startup. Only one instance exists +over the complete lifetime of pyload. Your hook can interact on various events called by the :class:`HookManager <module.HookManager.HookManager>`, +do something complete autonomic and has full access to the :class:`Api <module.Api.Api>` and every detail of pyLoad. +The UpdateManager, CaptchaTrader, UnRar and many more are realised as hooks. + +Hook header +----------- + +Your hook needs to subclass :class:`Hook <module.plugins.Hook.Hook>` and will inherit all of its method, make sure to check its documentation! + +All Hooks should start with something like this: :: + + from module.plugins.Hook import Hook + + class YourHook(Hook): + __name__ = "My own Hook" + __version__ = "0.1" + __description__ = "Does really cool stuff" + __config__ = [ ("activated" , "bool" , "Activated" , "True" ) ] + __threaded__ = ["downloadFinished"] + __author_name__ = ("Me") + __author_mail__ = ("me@has-no-mail.com") + +All meta-data is defined in the header, you need at least one option at ``__config__`` so the user can toggle your +hook on and off. Dont't overwrite the ``init`` method if not neccesary, use ``setup`` instead. + +Using the Config +---------------- + +We are taking a closer look at the ``__config__`` parameter. +You can add more config values as desired by adding tuples of the following format to the config list: ``("name", "type", "description", "default value")``. +When everything went right you can access the config values with ``self.getConfig(name)`` and ``self.setConfig(name,value``. + + +Interacting on Events +--------------------- + +The next step is to think about where your Hook action takes places. + +The easiest way is to overwrite specific methods defined by the :class:`Hook <module.plugins.Hook.Hook>` base class. +The name is indicating when the function gets called. +See :class:`Hook <module.plugins.Hook.Hook>` page for a complete listing. + +You should be aware of the arguments the Hooks are called with, whether its a :class:`PyFile <module.PyFile.PyFile>` +or :class:`PyPackage <module.PyPackage.PyPackage>` you should read its related documentation to know how to access her great power and manipulate them. + +A basic excerpt would look like: :: + + from module.plugins.Hook import Hook + + class YourHook(Hook): + """ + Your Hook code here. + """ + + def coreReady(self): + print "Yay, the core is ready let's do some work." + + def downloadFinished(self, pyfile): + print "A Download just finished." + +Another important feature to mention can be seen at the ``__threaded__`` parameter. Function names listed will be executed +in a thread, in order to not block the main thread. This should be used for all kind of longer processing tasks. + +Another and more flexible and powerful way is to use event listener. +All hook methods exists as event and very useful additional events are dispatched by the core. For a little overview look +at :class:`HookManager <module.HookManager.HookManager>`. Keep in mind that you can define own events and other people may listen on them. + +For your convenience it's possible to register listeners automatical via the ``event_map`` attribute. +It requires a `dict` that maps event names to function names or a `list` of function names. It's important that all names are strings :: + + from module.plugins.Hook import Hook + + class YourHook(Hook): + """ + Your Hook code here. + """ + event_map = {"downloadFinished" : "doSomeWork", + "allDownloadsFnished": "someMethod", + "coreReady": "initialize"} + + def initialize(self): + print "Initialized." + + def doSomeWork(self, pyfile): + print "This is equivalent to the above example." + + def someMethod(self): + print "The underlying event (allDownloadsFinished) for this method is not available through the base class" + +An advantage of the event listener is that you are able to register and remove the listeners at runtime. +Use `self.manager.addEvent("name", function)`, `self.manager.removeEvent("name", function)` and see doc for +:class:`HookManager <module.HookManager.HookManager>`. Contrary to ``event_map``, ``function`` has to be a reference +and **not** a `string`. + +We introduced events because it scales better if there a a huge amount of events and hooks. So all future interaction will be exclusive +available as event and not accessible through overwriting hook methods. However you can safely do this, it will not be removed and is easier to implement. + + +Providing RPC services +---------------------- + +You may noticed that pyLoad has an :class:`Api <module.Api.Api>`, which can be used internal or called by clients via RPC. +So probably clients want to be able to interact with your hook to request it's state or invoke some action. + +Sounds complicated but is very easy to do. Just use the ``Expose`` decorator: :: + + from module.plugins.Hook import Hook, Expose + + class YourHook(Hook): + """ + Your Hook code here. + """ + + @Expose + def invoke(self, arg): + print "Invoked with", arg + +Thats all, it's available via the :class:`Api <module.Api.Api>` now. If you want to use it read :ref:`access_api`. +Here is a basic example: :: + + #Assuming client is a ThriftClient or Api object + + print client.getServices() + print client.call(ServiceCall("YourHook", "invoke", "an argument")) + +Providing status information +---------------------------- +Your hook can store information in a ``dict`` that can easily be retrievied via the :class:`Api <module.Api.Api>`. + +Just store everything in ``self.info``. :: + + from module.plugins.Hook import Hook + + class YourHook(Hook): + """ + Your Hook code here. + """ + + def setup(self): + self.info = {"running": False} + + def coreReady(self): + self.info["running"] = True + +Usable with: :: + + #Assuming client is a ThriftClient or Api object + + print client.getAllInfo() + +Example +------- + Sorry but you won't find an example here ;-) + + Look at :file:`module/plugins/hooks` and you will find plenty examples there.
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