Comment by TazeTSchnitzel | Hacker News Reader

Comment by TazeTSchnitzel | Hacker News Reader

Parent Full thread

> The first thing I thought of when I looked at the PEP was, "this is like a string version of register_globals=on", which is an unsettling thought to have about Python, my favorite language.

> The idea of having a string that is automatically dynamic and whose value is hardly predictable upon first glance, wholly dependent on the stability of the code surrounding it, sounds like an absolutely horrendous idea.

What?! It's not a dynamic string. It's a string concatenation expression with syntactic sugar.

This isn't PHP's register_globals. It's PHP's "{$n + 1}".

What this does, you can already do. "Foo " + bar + " baz" already exists. This is merely nicer syntax.

The difference is,

> "Foo " + bar + " baz"

is not a string literal, neither is one using format or % function. All of those things return dead strings. This pep is about creating a kind of 'live' string literal, which python does not have right now (or need IMHO). So this is not merely a nicer syntax.

It is not live (unless I am mis-understanding what you mean by live) - it is evaluated once. That is to say:

    def magic(a, b):
        return f"{a} and {b}"

    s = magic(4, 8)
    print(s)
    a, b = 3, 7
    print(s)

prints `4 and 8` in both cases.

It is live in the sense that you can take that string literal and put it in a different context and it will result in a different evaluation, possibly yielding different value for the string and possibly different side effects (after calls to evaluate expressions).

Reply on news.ycombinator.com