'a' is str
b'a' is bytes
f'something' might be a separate f-str-type too?
1 is an int
1.2 is a float
(1.2 + 1) is a float
I would use such a feature, as I always use f-strings when formatting.
Because it would break existing strings containing braces, such as those used with `str.format`, or string.Template, or literal Jinja templates, ...
I suppose it's not that much of a problem to run a program to preprocess source and add in the F
But.. Python has a history of introducing new features that break old ones. That seems to me a balance between backward compatibility and future goodness.
the "from future import auto-fstring" construct could do it...
And, as for having to run the f-string parser: yes, but only once on static strings, which are most of them.
There are other issues you'd have to deal with as well. Would you interpolate non-literal strings (e.g. in the code `print(input())`, if the user inputs the string "{1+1}", what would be printed?)? How would you propose dealing with jinja and other strings that typically contain curly braces that should not be interpolated? This could also be an issue with (potentially long) strings containing lots of random characters: if a '}' showed up in a string somewhere after a '{', even if separated by tens or hundreds of characters, then you'll run into errors. This could be a problem if you're dealing with pseudorandom or base-92 encoded strings, or even just strings representing code (imagine a python library that generates C++ or Java code which has lots of hard coded strings with braces).
I think overall, having to specify that a particular string should be interpolated is a better solution than having to specify that a string should not be interpolated.
Unless you're using any dependency at all, including the standard library.
> But.. Python has a history of introducing new features that break old ones.
It doesn't tho.
> That seems to me a balance between backward compatibility and future goodness.
That assumes "everything is an fstring" is considered "future goodness", which I'm not sure is a widely shared view.
> the "from future import auto-fstring" construct could do it...
That seems unlikely as the __future__ pseudo-package has generally been used to opt into hopefully future behaviour.
Given the Python 3 experience, somehow, I don't see "let's make all string literals into fstrings" happen any time soon, but hey feel free to create a PEP proposing that.
Alternatively, create your own import hook which does this swap before handing the module off of to the compiler.
f-strings, like r-strings, have uses, but, like r-strings, I wouldn't want to replace plain strings with them.
Might also be a performance penalty for always having to run the fstring parser.
