Sapphire - Imagine a framework•8mo ago

Extending Listener base class

So I wanted to extend the Listener base class by running some code for every listener before the actual run handler is invoked. Ideally I'd like to shim it somehow so existing listeners still just implement run so removing or adding more shims like this is easily possible without renaming methods implemented in the listener itself.

13 Replies

BigBrainAFKOP•8mo ago

I am expecting this just isnt possible with how inheritance works and would require changes to the Listener class of saphhire

Favna•8mo ago

export class MyCustomListener extends Listener() {

  public override run(the args go here) {
    customCodeGoesHere();
    super.run(the args go here);
  }

export class MyCustomListener extends Listener() {

  public override run(the args go here) {
    customCodeGoesHere();
    super.run(the args go here);
  }

isn't this just what you want? Then you extend MyCustomListener in your pieces that need to run the code and extends Listener for those that dont

BigBrainAFKOP•8mo ago

yeah but this doesnt work cause super has no run method as its an abstract method oh wait it overrides the run yeah no still limited due to abstract not being callable/accessible

Favna•8mo ago

oh wait right yeah well then you dont need to call the super at all. just extend the class then make your class extend your extended class

// src/listeners/custom.ts

export class MyEvent extends MyCustomListener {
  public override run(...) { 
    super.run();
  }
}

// src/listeners/custom.ts

export class MyEvent extends MyCustomListener {
  public override run(...) { 
    super.run();
  }
}

// src/other/or/something/MyCustomListener.ts
export class MyCustomListener extends Listener {

  public override run(the args go here) {
    customCodeGoesHere();
    
  }
}

// src/other/or/something/MyCustomListener.ts
export class MyCustomListener extends Listener {

  public override run(the args go here) {
    customCodeGoesHere();
    
  }
}

BigBrainAFKOP•8mo ago

yeah that would fully override the run of the custom listener though

Favna•8mo ago

edited

BigBrainAFKOP•8mo ago

ah yeah the super call is what i wanna sort of avoid as it would mean duplicate code again (i could just call another function the without having a custom listener). i guess ill just have a different abstract function in my custom class and run that one from its implementation of run and then ill just have to compomise with that

vladdy•8mo ago

you technically could override our internal _run method for it, but be careful

BigBrainAFKOP•8mo ago

yeah no thats smth id not want to do personally. they are internal for good reasons usually. might be something nice to have though as an extendable optional feature to have pre and post functions on the listener class which can be handled by a custom listener class

Favna•8mo ago

just keep in mind that if we add that, then an error in prerun or postrun wont end up in ListenerError https://github.com/sapphiredev/framework/blob/4cc93a925916346bd713dff1e015dc0092e10bcf/src/lib/structures/Listener.ts#L98-L101 we'd get PreListenerError and PostListenerError

BigBrainAFKOP•8mo ago

yeah that would be fine though as it also means that its easier to know if the error is from the listener itself or a pre/post condition

Favna•8mo ago

only thing I'm doubting about now is how far we want to take this. For example do we want all Pieces to support it. And if we do, then how do we handle messageRun vs chatInputRun vs contextMenuRun for commands.

vladdy•8mo ago

commands already have pre and post events realistically, all _run does is call your actual run method and emit listenererror if an error is thrown

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Extending Listener base class