Be Careful with Python's New-Style String Format

I do love writing python, but it's pretty shocking when I find out you can write something like `event.__init__.__globals__[CONFIG][SECRET_KEY]`. That language just does not care about privacy or information hiding at all, I guess.

Re: Be Careful with Python's New-Style String Format

#6

Post by [deleted] » Sat, Dec 31, 2016, 7:26 PM UTC

dlbucci wrote: post #5

I do love writing python, but it's pretty shocking when I find out you can write something like `event.__init__.__globals__[CONFIG][SECRET_KEY]`. That language just does not care about privacy or information hiding at all, I guess.

[deleted]

Re: Be Careful with Python's New-Style String Format

#7

Post by tedunangst » Sat, Dec 31, 2016, 7:28 PM UTC

coldtea wrote: post #4

Err, why would you allow for the user to enter arbitrary format strings in the first place? Might as well write "be careful about eval of arbitrary user provided strings".

"Customize the look of your blog by editing these templates."

Re: Be Careful with Python's New-Style String Format

#8

Post by hakanderyal » Sat, Dec 31, 2016, 7:30 PM UTC

dlbucci wrote: post #5

I do love writing python, but it's pretty shocking when I find out you can write something like `event.__init__.__globals__[CONFIG][SECRET_KEY]`. That language just does not care about privacy or information hiding at all, I guess.

Python's general mentality can be summed as "We are all consenting adults here". If you want to access some part of program or data, you generally can, but the burden of not breaking anything while messing with internals is on you.

This is a great power, but also can become an unlimited source of bugs.

Re: Be Careful with Python's New-Style String Format

#9

Post by Animats » Sat, Dec 31, 2016, 7:33 PM UTC

No, Rust does not have the ability to access any variable in the program via a format string. Rust has this:

   format!("{argument}", argument = "test");   // => "test"

That's just named arguments to the format. Also, that's a macro; it's expanded at compile time.

Python's approach is lame. It should have used something with a limited list of named arguments, or maybe a dict.

Re: Be Careful with Python's New-Style String Format

#10

Post by the_mitsuhiko » Sat, Dec 31, 2016, 7:34 PM UTC

atabdiwa wrote: post #3

... Uncontrolled format string bugs? In 2016? Really? Someone would fall for that? ..

Old style format strings are perfectly safe for arbitrary user input and commonly used as such.