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When you're supposed to use Rust, but you only know Python... (crates.io)

submitted 1 month ago by Ephera@lemmy.ml to c/programmerhumor@lemmy.ml

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So, this uses a macro, but if you're thinking anything is possible with a macro, it's actually not in Rust. The input does still need to parse as valid Rust tokens.

Which means the authors asked themselves at some point: Is the Rust syntax a superset of the Python syntax?
And well, it's not. In particular, some Python keywords will just be tokenized as an identifier (like a variable name).

But it is close enough that the authors decided against requiring a massive string to be passed in, which does amuse me. 🙃

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[–] JoYo@lemmy.ml 8 points 1 month ago* (last edited 1 month ago) (1 children)

is it converting the syntax to rust? wouldn't that be easier at the LLIL or i guess python bytecode level?

[–] Ephera@lemmy.ml 13 points 1 month ago* (last edited 1 month ago) (1 children)

From what I understand, it works like this:

Rust compiler reads the pseudo-Python and tokenizes it according to Rust's rules.
Macro code converts the tokens back to (now proper) Python, while filling in the captured variables. I believe, this is the code that does this.
Python code is executed in an actual Python interpreter, via PyO3.

[–] JoYo@lemmy.ml 6 points 1 month ago

oh ok nm i misunderstood. thanks