How I added C-style for-loops to Python (tushar.lol)

submitted 2 years ago by jnovinger@programming.dev to c/python@programming.dev

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Via https://framapiaf.org/@bitecode/110656440273902608

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[-] o11c@programming.dev 3 points 2 years ago

The with approach would work if you use the debugger to change the current line I think.

I don't understand why this stop using ASTs in favor of buggy regexes - you're allowed to do whatever you want during the codec ...

Don't forget to handle increment before continue.

The main time I miss C-style for loops is dealing with linked lists and when manipulating the current iteration.

The former should be easy enough - make the advancement provide __getattr__ expressions.

The latter already works since it is in fact being transformed into a while. It's impossible if you try to use for though.

[-] qwop@programming.dev 2 points 2 years ago

If it's valid syntax you can technically do pretty much whatever you want at runtime with enough hacks. I know pytest does some pretty crazy stuff to get nicer error messages from asserts (e.g. so it can display the value of a and b for assert a == b)

As soon as it's invalid syntax it becomes harder. You can't parse it into an ast, which I assume is why they used regex.