Here is a more in-depth tutorial.
https://zetcode.com/python/fstring/
Python 3's F-Strings: An Improved String Formatting Syntax
11–20 of 147 posts
Re: Python 3's F-Strings: An Improved String Formatting Syntax
#12> However, once you start using several parameters and longer strings, your code will quickly become much less easily readable [...] `"Hello, %s %s. You are %s. You are a %s ...`
Minor correction: % formatting allows specifying names for dictionary keys too:
In [1]: "%(a)s and %(b)s" % {"a":"A", "b":"B"}
Out[1]: 'A and B'
But I do like f-strings and am using them quite a bit. Calling functions or methods inside f-strings is something I had no idea was possible. That is pretty neat:
>>> name = "Eric Idle"
>>> f"{to_lowercase(name)} is funny."
'eric idle is funny.'Re: Python 3's F-Strings: An Improved String Formatting Syntax
#13I can't say I like the f" syntax much. I think JS's backtick is better. Other than that, I agree, much better than % and less verbose than .format. It's just the f" or f' that doesn't sit right with me
I agree it's not the most beautiful, but it was the best choice given the requirements. Basically, it had to be explicit, concise, use unused ASCII syntax, and not be too cryptic or incompatible. Other quote types or backticks were not available or an option.
(I spent a lot of time thinking about it, and put the idea forward on python-ideas. Though string interpolation is nothing new of course.)
Re: Python 3's F-Strings: An Improved String Formatting Syntax
#14I can't say I like the f" syntax much. I think JS's backtick is better. Other than that, I agree, much better than % and less verbose than .format. It's just the f" or f' that doesn't sit right with me
I think you are right to prefer JS's backtick notation, but not in your reason.
The main problem with python's f" syntax is that it's just a very complex, non-extensible hack whereas in javascript you can prefix a tag to specify how the interpolation happens.
Instead of this, f-strings have a lot of hardcoded and often broken behavior which can't be fixed let alone customized. For example, you can specify a field width, but it will not even work properly even in a fixed-width context, because of quite common things like emojis or CJK or combining characters don't have their width computed correctly.
Re: Python 3's F-Strings: An Improved String Formatting Syntax
#15> However, once you start using several parameters and longer strings, your code will quickly become much less easily readable [...] `"Hello, %s %s. You are %s. You are a %s ...` Minor correction: % formatting allows specifying names for dictionary keys too: In [1]: "%(a)s and %(b)s" % {"a":"A", "b":"B"} Out[1]: 'A and B' In fact I had never switched to using str.format as it just never added enough benefit for me ov…
f"{name.lower()} is funny."Re: Python 3's F-Strings: An Improved String Formatting Syntax
#16PHP: Am I joke to you?
> PHP: Am I joke to you?
JFYI meme style responses are frowned upon at HN. That's why you get downvoted.
A much better rephrase of the above would be something along the lines of:
PHP/Javascript/.. also have this feature since ver X. It's main difference/advantage/disadvantage is ...
Re: Python 3's F-Strings: An Improved String Formatting Syntax
#17F-strings have been around for years and this article is at least a few years old. I'm curious why this is coming up now.
I wonder if the submitter was inspired by this tweet that went viral (by python standards) yesterday: https://twitter.com/mariatta/status/1351359518316216321
Re: Python 3's F-Strings: An Improved String Formatting Syntax
#18This reminds me of Swift's string formatting syntax:
let name = "Bob"
print("Hi my name is \(name)")
Re: Python 3's F-Strings: An Improved String Formatting Syntax
#19I can't say I like the f" syntax much. I think JS's backtick is better. Other than that, I agree, much better than % and less verbose than .format. It's just the f" or f' that doesn't sit right with me
I think you are right to prefer JS's backtick notation, but not in your reason. The main problem with python's f" syntax is that it's just a very complex, non-extensible hack whereas in javascript you can prefix a tag to specify how the interpolation happens. Instead of this, f-strings have a lot of hardcoded and often broken behavior which can't be fixed let alone customized. For example, you can specify a field wid…
It's not a hack or broken. The formatting language existed before f-strings and is somewhat a separate issue.
I'm not sure I expect it to handle every Unicode nuance either, when there are modules in the stdlib for that.
Re: Python 3's F-Strings: An Improved String Formatting Syntax
#20Earlier quoted context omitted.
Yup, especially as you often need to access dict's with foo["field"] and you get a syntax error if the f-strings is also f"". JavaScript backtick syntax doesn't lead to this extra syntactic friction.
You can use any of f"{foo['field']}" f'{foo["field"]}' f"""{foo["field"]}""" (I see from your carefully worded first sentence that you already knew this but still find it annoying, but I'll leave this here for any that aren't aware.)
Yes, and anyone who has written a "one-liner" at the command line is familiar with it. Wouldn't say it is a big problem.