There's a couple things wrong with this code. But let's start with the wrong assumption(s) that led you to try this in the first place.
> I've realized that storing the entire object requires a lot of memory Your object is the size of an integer, so it is exactly the same size as a pointer. Of course if you add more fields this will add up, but you need to store the data in your object somewhere, often just having it in a table is the right choice. But let's say your object actually is massive, and you want to avoid copies. The object you've got there is also a `ref object`, this means that when you create it, it is allocated on the heap, and whenever you pass the object around you're actually just passing around a pointer. It will be automatically freed once the last reference to it goes out of scope, and you can basically just relax. So having `Table[string, myObj]` would actually just store pointers already, no more fuzz! If you need to pass a `ref object` to a C function you can use `addr` to tell Nim to give you the pointer instead of abstracting it away, just keep in mind that the reference needs to stay in scope as long as the C code wants to access it. With that said, let's have a look at your code. The problem here is pretty much the exact thing I warned against, you create a `myObj` as a local variable in your function, then you manually store a pointer to it in the table, circumventing Nims reference counting, then you return. As you return from this function Nim sees that `myObj` goes out of scope, and since you just circumventing the reference counting that's the only reference Nim knows about. So Nim diligently frees your object since you're no longer using it. Once you try to use it later on it isn't actually a `nil` dereference issue, but rather a user after free issue. Putting the contents of `initTableObj` into `callTableObj` just means that the local variable doesn't have time to go out of scope before you try to use it, and as such Nim hasn't gotten around to free it yet. Hopefully that helps, and welcome to the Nim community!
