The difference between a |= b and a = a | b is exactly the same as the difference between a += b and a = a + b. Nothing new about that, try:

a = [1]
b = a
b += [2]
b.append(3)
b = b + [4]
b.append(5)

print(a)

or see: https://fosstodon.org/@bterwijn/116328991093782469

For immutable types there is no difference between a += b and a = a + b, try with a tuple.

It's mainly targeted to Python programmers at: https://programming.dev/c/python

The Solution link gives you a visualization of program execution, I've started to make the same sort of visualizer for C. What do you think?

C already has that class of operators, but lacks a set in the base language.

You are probably interacting with analogous operators all day long.

I don't see why extending those notions would cause you issues as a C programmer.

Thanks, maybe I should have added that possible answer instead of 'D', adding one more feels too many.

If you are interested see the dictionary docs (https://docs.python.org/3/builtins/stdtypes.html#dict):

d |= other Update the dictionary d with keys and values from other, which may be either a mapping or an iterable of key/value pairs. The values of other take priority when d and other share keys. Added in version 3.9.

Pick your answer and check the Solution link.

I didn't have previous exposure to that exact syntax either, but:

• Python and plenty other languages have assignment variations with an operator like +
• | in plenty of languages means logical OR
  • possibly bitwise, but that seems unlikely in Python
• Dicts are sorta complex siblings of sets
• In terms of sets, OR is equivalent to a union

Hence, a |=b should have the same meaning as a = a | b or a = a.union(b)

and then the quiz is about basically implementation details and what the actual semantics winds up being in a language like python, where stuff is mutable by default and references are implicit (even though the zen of python states a preference for being explicit)

The dict union operator is similar to that of set, but in addition the right operand overwrites values of keys of the left operand. It's a nice operator once you get used to it.

Easy to make a mistake with this exercise:

• first realize b = b | {3: []} makes a shallow copy
• then realize the shallow copy still references the value of key 2 in a so we can still append to that and change a

Can you tell me what the problem is for you when you click the first link? I tried to make it work for all browsers (even mobile, but the UI isn't very mobile friendly), so I would like to get it working on your system too. If you can give me a bug report (and maybe try from different system), that would be great.

The second link explains:

• mutability: https://github.com/bterwijn/memory_graph#mutable-type
• shallow copy: https://github.com/bterwijn/memory_graph#copying-values-of-mutable-type
• difference between x += y and x = x + y: https://github.com/bterwijn/memory_graph#name-rebinding

It's left to the reader to generalize this to x |= y vs x = x | y.

This is what the solution link is supposed to give you at the end of the execution animation:

It's hard to support all mobile browsers, on some it does work.