Notices by James C :python: (jamescooke@fosstodon.org)

When is 0 not 0? When SymPy made it into an instance of its special Zero class of course! 😅

*AND* you can't convert that to a Decimal by just casting it either 😬

#Python

@wizzwizz4 Testing zero with `is` is safe because it's got a fixed memory address: https://realpython.com/python-is-identity-vs-equality/#when-only-some-integers-are-interned

Try your code with 256 and 257 - you'll see that 256 gives True and 257 gives False.

@wizzwizz4

> You should not be writing code that relies on this behaviour in the first place.

I'm not.

That was just a screenshot of ipdb where I was debugging and surprised that an instance printed as "0" but wasn't the int 0.

Happy to add a screenshot with a better way of demonstrating that the value I had in the dictionary was `sp.S.Zero` and not `int(0)`, even though they `== 0` as `True` - what _should_ I have done?