How should I respond to a student who proposes a "weak" analogy?
The concrete example:

Your student is right. At least, I agree with him, because I think of event listeners in the same way.

When multiple callers register for the same event, and the event triggers, it "calls everyone back". Functionally, it's similar to how an array or list is processed, e.g. :

foreach (var caller in callers)
{
    caller.Call();
}


The thing about abstract fields such as programming and mathematics is that people will find what works for them. Not everyone sees it the same way.

I may be biased because me and the student apparently see it the same way; but I'm actually having a hard time poking holes into his argument, without having to resort to fairly avanced event handling (and even then, the analogy sort of works).



Anecdotally:

A simple example for math applies to me. When considering the average of two numbers, most people think to themselves:

average = (A + B) / 2;


However, I instinctively used another pattern:

average = A + (B-A)/2 


Note that A is always the smallest number.

This looks a lot more contrived. I agree. But to me personally, it was easier to do it like that. I'm someone who uses number forms to visualize numbers in my head, which means I do simple calculations visually (sort of, it's hard to explain).

When you ask me to calculate the average of 45 and 51, what I see in my head is:


  ... 43 44 45 46 47 48 49 50 51 52 53 ...


I take the numbers between the boundaries:


  46 47 48 49 50


And I find the middle number.


  48


When you look back at "my" formula, maybe you'll see that the order of operations is the same as this visual example. Take the difference, split it in two, find what's in the middle.
To me, it makes perfect sense, and I am considerably faster when calculating averages (of 2 numbers) this way.

I reverted to using the more standard approach when math classes started requiring us to calculate the average of more than 2 numbers. But for finding the average of two numbers, I still use my own method to this very day.



How to respond:

Even though the student is correct (in his own way), if you simply agree with his stance, others may misunderstand him (because they e.g. think of arrays in a different way than the student who raised the analogy).

You need to approach it correctly, because you can't err on either side:


If you tell the student he is wrong (for the sake of the other students), then he will be incredibly confused. I've been on the receiving end of this, and it took me some time to regain the confidence to use my own averaging method.
If you tell the student he is right (for the sake of the student), then the other students may end up incredibly confused.


So when you respond, make it clear that you understand what the student means, but it's not exactly the same in every way.

For example:


  I see what you mean, and this particular case does indeed behave similar to an "array of listeners". But there are other cases where the analogy doesn't quite work, so be aware of that.


Or:


  I can see where you're coming from. As you now understand it, there are indeed some similarities. However, once we delve into more advanced examples, you'll start to notice that it's not quite the same. Try to not stick to the analogy because you'll end up expecting different behavior.


I think this sticks to the middle of the road:


It confirms the student's basic interpretation of the code's behavior.
It highlights that the analogy is not perfect and flawed when applied to other cases.
Other students who have no idea what the student was talking about (because they understand it in a different way) will understand that the analogy is flawed and not generally usable, so they won't fixate on understanding why this analogy sort of works and will instead be more likely to ignore it and move on.


There are of course countless ways to respond, but you should always try to find a compromise that both confirms the student's vague suspicion, suggests that it only works in particular cases, and it avoids creating confusion for the other students.

Specifically for this example, my response would be:


  Yes, even listeners can be considered as an "array of listeners" where you can add/remove listeners as you please. However, "an array of something" is an incredibly common concept in programming. Whether it's getting data from a database (a table is an array of entries) or parsing a string (which is an array of characters), you'll find arrays and lists everywhere you look.
  When we get to the more advanced part of the curriculum, almost everything will use an array-like approach at one point or another.