Question

I acknowledge that they can be useful, but I’m trying to wrap my head around when I would actually want to have a func as a parameter of a method.

public void WeirdMethod(int myNumber, func op);

In terms of design and functionality, could someone explain to me some circumstances where I would want to consider this? Theories of “reusability” isn’t going going to help me much. Real world scenarios would be best. Help me think like you lol.

Here’s about all I know:

• This would allow me to pass a delegate
• This would allow me to use a lambda expression.

Yeap…

NOTE:
I know this thread will get closed since there’s no “right” answer. But I think what clicked it for me just now was “delayed calculation”.

Answer 1

A general scenario is when you must pass a delayed calculation to your method. This is useful when calculating something is expensive, for example, when you cache something.

public Guid GetFromCache(string key, Func<Guid> make) {
    Guid res;
    if (!cache.TryGetValue(key, out res)) {
        res = make();
        cache.Add(key, res);
    }
    return res;
}

Now you can call this method as follows:

Guid guid = GetFromCache(myKey, () => database.MakeNewGuid());