An exercise to help build the right mental model for Python data.
- Solution: https://memory-graph.com/#codeurl=https%3A%2F%2Fraw.githubusercontent.com%2Fbterwijn%2Fmemory_graph_videos%2Frefs%2Fheads%2Fmain%2Fexercises%2Fexercise9.py&play=
- Explanation: https://github.com/bterwijn/memory_graph?tab=readme-ov-file#python-data-model
The “Solution” link visualizes execution and reveals what’s actually happening using 𝗺𝗲𝗺𝗼𝗿𝘆_𝗴𝗿𝗮𝗽𝗵: https://github.com/bterwijn/memory_graph
I expect A if “b” is a clone, or E if it’s a reference. But I also wouldnt combine array operations like this.
The answer being C feels like a bug.
In my limited understanding, the 5th step
b = b + [4]would cause problems, infinite execution or alike, if it kept being a reference.Coming from MATLAB, anything but A feels like a bug. I don’t want my script to use references when initializing a variable unless I tell it to.
Eh, I get it. The equal operator creates a reference but the plus operator isn’t destructive so it creates a new list and overwrites the variable b with a new list, when assigned.
Of course, this would all be avoided if creating copies was the norm; which is why I stick with functional languages.
Copying a list with a million elements every time you make a small change is not fun. Sure, you can optimize a bit behind the scenes, but that still gives a lot of overhead.
And we can create data structures and algorithms that fit a more functional style without relying on imperative assumptions of how data should be handled. Data structures like vlists could be applicable, for example.