This is a circular dependency issue. For declaring a pointer to some class, the definition of the class is not needed; i.e. the type doesn’t have to be a complete type. So you don’t need to include A.h in B.h, forward declaration is enough. Such as:
The way to think about this is to “think like a compiler”. Imagine you are writing a compiler. And you see code like this. When you are compiling the .cc file (remember that the .cc and not the .h is the unit of compilation), you need to allocate space for object A. So, well, how much space then? Enough to store B! What’s … Read more
I think the answer by jpmc26, while by no means wrong, comes down too heavily on circular imports. They can work just fine, if you set them up correctly. The easiest way to do so is to use import my_module syntax, rather than from my_module import some_object. The former will almost always work, even if my_module included imports us back. The latter … Read more
I have four different files named: main.py, vector.py, entity.py and physics.py. I will not post all the code, just the imports, because I think that’s where the error is (If you want, I can post more). main.py: entity.py: vector.py: physics.py: I then run from main.py and I get the following error: I’m guessing that the error is due to importing entity twice, … Read more