understand the following lambda

Question

I have a method like

void Test(Func<bool> f)
{
    f.Invoke();
}

I pass in the Test( ()=>GetItem("123") )

f.Invoke() actually called GetItem("123").

I want to know how does f know GetItem has a parameter?

Answer 1

Your function Test takes a function as a parameter. It will invoke whatever function is passed in as an argument.

In this case, when you create your lambda () => GetItem("123"), you are creating a function that takes no arguments, and invokes GetItem("123").

Test has no knowledge about the value of the parameter passed to GetItem, nor does it need to, because the value of the parameter is hardcoded in the lambda.

Answer 2

You're question is a bit confusing. F doesn't know what's required by Getitem.

When you created the lambda, a "pointer" was returned to the place in the memory where a method is located. That method contains the line of code return Getitem("123"). When you invoke F, what actually happens is a kind of jump to a pointer. F is like a "pointer" to that place in the memory where the function is located.

So, to answer your question, F doesn't know what Getitem needs, F just calls the function your wrote, and that function has the "123" parameter hard coded.

Remember that lambda is a type of Delegate