Question

In my app, I wanted to let class B get some information from class A but as A instantionates B, B has no reference to A (intentionally).
I have never used events for that purpose so I am not sure whether its correct, but it works:

class A
{
 public delegate bool GetFromB();
 public event GetFromB GetDataFromB;
...

//get data from B without having an access to it
bool Result=GetDataFromB();
}

class B
{
A a=new A();
A.GetDataFromB=new A.GetFromB(DO_THAT);

public bool DO_THAT()
{
 ...
return true;     //and that is it, it will return to event caller
}

}

Answer 1

It’ll certainly work, and that approach is used in a few places in the core framework – AssemblyResolve etc. Alternative approaches here:

• if it is used by a method, pass it into the method as a callback delegate. Same approach, but simply not exposed as an event
• ditto, but with an interface

but it’ll work that way. It isn’t unheard of. Code tweaks, though:

A a=new A();
a.GetDataFromB=+new A.GetFromB(DO_THAT);

you subscribe on the instance (unless it is static), and need +=, not =.

Also: consider using Func<bool> rather than declaring your own delegate type.