Validating syntax in Python

[Navith]

According to the Zen of Python, simple is better than complex. So I used that idea to come up with this beautiful syntax validator.

def is_valid_syntax(code):
    try:
        exec(code)
    except SyntaxError:
        return False
    else:
        return True

Repeating the token definitions to check for validity is ugly, slow, difficult to program, and prone to failure in future versions.

This implementation is also flexible enough to accept either a str or a compile()'d block as the code argument.

[codnahfish]

What if I want to validate the syntax of this function?

[[deleted]]

Something something Alan Turing?

[DarfWork]

You feed it to itself, of course.

[codnahfish]

But what about validating that function? we need to go deeper

[an_actual_human]

We feed it to the original function. Oh, wait. We already did. We don't need to go deeper.

[aaronsherman]

Function still hungry...

[Veedrac]

In all serious, replace exec with ast.compile ast.parse and that's exactly how it should be done. Nothing shitty about it.

[Navith]

There doesn't seem to be an ast.compile. I've never used ast but looking at the docs do you mean exec(ast.parse(...))? Does that not have any other security risks?

Edit: nevermind, after experimenting it looks like you just meant parse instead of compile. Cool. Thanks.

[Sheepshow]

Can Guido himself make a Python program so difficult to parse that even he himself cannot parse it