Get the handle of a function of a class that has no instantiation yet

问题

I am fairly new to C#.

What I want to do may seem convoluted. Let's start by saying that I want to take a handle of some functions in order to execute them later on. I know that I can achieve this in the following way:

List<Action> list = new List<Action>();
list.Add( () => instanceA.MethodX(paramM) );
list.Add( () => instanceA.MethodY(paramN, ...) );

for(Action a in list) {
    a();
}

However, what if the instanceA object does not exists yet, but I know it will exists when I call the corresponding function? MethodX and MethodY are on an external library that I am not supposed to modify.

-why: think about this situation: the class A has 100 Methods, each returning a different float depending on the class A state. However, depending on some other state, we may want to access only the first 5 methods, or only the first and the fourth method. The class state to which this method applies may change over time. My idea was to have a big lists with all the 100 methods, then by using indexes corresponding to the method, create a sublist LL with only the appropriate methods (for example, [1,2,3,4,5], or [1,4]). Then, once that the object A is created, I would run in turn all the different method in the sublist LL, somehow as they were called by the object A.

Any idea about how to achieve that?

回答1:

You can use List<Action<YourClass>>, then add like:

lst.Add(x => x.Method1());
lst.Add(x => x.Method2());

Then when you want to execute the method you pass in the instance:

lst[0](theInstance);

来源：https://stackoverflow.com/questions/40116771/get-the-handle-of-a-function-of-a-class-that-has-no-instantiation-yet