Hooks

  • What is a hook?

  • A hook is basically just a thing where you redirect a function call to another, a lot mods (not just GD mods!) rely on function hooking.

  • How does Serpent handle function hooking?

  • Serpent looks for a ClassName_FunctionName function within your script's class, if it exists, then it would hook ClassName::FunctionName (note that ClassName::FunctionName should be a function available to hook within Serpent and geode itself for the hook to be initialized!)

Creating a simple hook

  • Let's replace the MenuLayer's onMoreGames function!

  • Steps:

  • First, we call script.initAllHooks in __init__ for the hooks to initialize.

  • We define a function named MenuLayer_onMoreGames within our script's class.

  • then pass self, this as the first two arguments, Serpent requires these two arguments so we'd be able to call the original if we need to (we will explain what an original is later.)
  • Then we just pass whatever arguments MenuLayer_onMoreGames takes, in this case it's a single argument, it can have any name you want.

  • Our function's signature is: MenuLayer_onMoreGames(self, this, sender)

  • Code:

class simplescript_yellowcat98:
    def __init__(self):
        self.script = script("simplescript_yellowcat98", self)

    def MenuLayer_onMoreGames(self, this, sender):
        popup = FLAlertLayer.create("Popup Title", "This is the body of a popup.", "i think this is the button!") # create a popup.
        popup.show() # show the popup to the screen!

if __name__ == "__main__":
    simplescript_yellowcat98()
  • Now you have hooked a function!

Calling the Original

  • What is the original in terms of function hooking?

  • It's just the function you hooked, since all hooking does it just redirect function calls, the original in fact still exists and is callable!

  • In Serpent, we take advantage of the this argument, this is of type MenuLayer, MenuLayer is a class which contains the original.

  • Let's call the original in a MenuLayer_onQuit hook!

  • (the onQuit function is the function that gets called when you press the X button in the main menu.)
def MenuLayer_onQuit(self, this, sender):
    self.script.info("Before original!")
    this.onQuit(sender) # Make sure to pass any required arguments! excluding `self, this`
    self.script.info("After original, btw this info function prints to the geode platform console because the regular print function doesnt show you the script's name!")