C#•2y ago

✅ How do i pass a function with unknown parameters?

for instance

void WrapFunction()
{
    return 1;
}

void WrapFunctionA(dynamic data);
void WrapFunctionB(int data);
void WrapFunctionC(string data);

void CallFunction(Func<?> passed_func) { passed_func(); }

CallFunction(WrapFunctionA);
CallFunction(WrapFunctionB);

void WrapFunction()
{
    return 1;
}

void WrapFunctionA(dynamic data);
void WrapFunctionB(int data);
void WrapFunctionC(string data);

void CallFunction(Func<?> passed_func) { passed_func(); }

CallFunction(WrapFunctionA);
CallFunction(WrapFunctionB);

```

16 Replies

Anton•2y ago

if the return type is void, it's an Action Func will always have a parameter, since it's by definition a delegate with a non-void return type oh you can't

boom•2y ago

what would be the closest method alike? basically, with more context

Anton•2y ago

you either have to use MethodInfo, reflection checks, or multiple overloads, or wrap your delegates in a class

boom•2y ago

i have an "event bus", that once passed a <random> function, with unknown parameters it will execute without needing to know the parameters of given func

Anton•2y ago

yeah the best way is to make an adapter class for that function or an adapter delegate that casts the argument to the expected type

boom•2y ago

the method i was going down, was having a separate class for the arguments, and using the "argument stack" for the functions to use

boom•2y ago

boom•2y ago

haven't fully written the class out yet, but the event will have a callback that's overrode later on is this sort of the method your referring to?

Anton•2y ago

you'll have to box if you don't do generics throughout your whole event system so kinda like this

Action<object> Wrap<T>(Action<T> f) => (object arg) => f((T) arg);

Action<object> Wrap<T>(Action<T> f) => (object arg) => f((T) arg);

boom•2y ago

wtf am i seeing 😂 im not too familiar with c# syntax lol

Anton•2y ago

but if you don't want to box then the approach eill be completely different

boom•2y ago

i also dont know what boxing is, sorry lol

Anton•2y ago

Action<object> Wrap<T>(Action<T> f)
{
    return (object arg) => f((T) arg);
}

Action<object> Wrap<T>(Action<T> f)
{
    return (object arg) => f((T) arg);
}

like this, if it makes it easier on the eyes you can't make a generic event bus in C# that supports managed structs without boxing, even with unsafe, due to some unfortunate GC rules around references. It would only work with unmanaged structs + some unsafe things but with boxing, or if your event data are classes, the wrapper I just showed should do just fine this code isn't right tho, where's the only argument? you aren't passing anything in the end anyway, you might want something more straightforward look into the adapter pattern

boom•2y ago

just a bland representation. i think i got it figured out sort of. appreciate your help g

Anton•2y ago

Accord•2y ago

Closed!

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✅ How do i pass a function with unknown parameters?