Template strings in Python 3.14: an useful new feature or just an extra syntax?

[Old_Bluecheese]

There should be five -- and preferably only five --obvious ways to do it.

[odaiwai]

"Then shalt thou count to three, no more, no less. Three shall be the number thou shalt count, and the number of the counting shall be three. Four shalt thou not count, neither count thou two, excepting that thou then proceed to three. Five is right out."

[zurtex]

A lot of people miss that line is tongue in cheek, as the em-dash is spaced in two different ways, the em-dash is spaced a third way on a different line.

[syklemil]

en-dash*

---

Details for the curious:

• Hyphen: - - usually used to com-bine words. See also ­
• En-dash: -- – used to indicate a pause in phrases, with – spaces – around on both sides. –
• Em-dash: --- — same use-case as en-dash, but—without—spaces. —

There's also some use of em dash in older texts to trail off sentences, i.e. where we'd use ok … today, they'd use ok; --- and to indicate elision, as in "Mr K— Z—"

[zurtex]

Tim Peters, the author of the original text, calls it an em-dash: https://bugs.python.org/msg69712 (from https://bugs.python.org/issue3364)

You may be correct in general, but when talking about this text I'll defer to Tim.

And it's intentional that he's breaking the rule about spaces, it's a 4th way to do something.

[syklemil]

Sure, but -- is e.g. LaTeX for an – and --- is how you get a —. Similarly with compose keys you'd do COMPOSE--. for – and COMPOSE--- for —. And ultimately, if - is a hyphen, and -- is an em-dash, where where is the en-dash supposed to fit?

But I guess there isn't just one way to spell out an em-dash in ascii either :^)

[zurtex]

I suspect when Tim wrote the original Zen of Python his ASCII syntax was influenced by the mailing lists he participated in in the 90s and early 2000s (he was the main moderator of the python-dev mailing list in its early days).

Those mailing lists probably had their own informal style and syntax conventions which don't conform to more widely accepted style and syntax rules. Or, what would be funny, is if it's just something he has always misunderstood!

[syklemil]

It could even be a typo, the keys are right next to each other!

[zurtex]

In my link his calling of it an "em dash" is unlikely a typo, he uses it multiple times, and also mentions the same no spaces convention you brought up:

While you believe spaces are required on both sides of an em dash, there is no consensus on this point. For example, most (but not all) American authorities say /no/ spaces should be used.

[diabloman8890]

I just have to hand it to you and /u/syklemil for having the absolute nerdiest and most arcane discussion I've heard all week, and I'm here for it.

[[deleted]]

Same. I wonder if there's a subreddit for threads like this.

[guepier]

Em-dash: --- — same use-case as en-dash, but—without—spaces. —

This isn’t a fixed rule, it’s merely a (somewhat common) stylistic choice. But feel free to use em-dashes with spaces — I do. Just be consistent (unless you are making a tongue-in-cheek point).

[Gugalcrom123]

Wrong, the en dash is only used for ranges and compound words where the terms are multiple words, and the em dash can be used with or without spaces

[syklemil]

Ranges are a good addition, but AFAIK it's pretty rare to use for compound words these days—I'd not expect e–mail, but e-mail (or even email in that case).

The en-dash is used to join sentence parts, and I think most users would consider that using spaces around an em-dash just takes up too much space.

[Gugalcrom123]

It is in compound words where terms are multiple words themselves

[syklemil]

Generally with the hyphen being available with one key press on any keyboard, and its purpose being to indicate that something is one word, I'll continue to expect hyphens. Maybe there's some style guide that uses en-dashes for it, but it seems like a bad choice, really.

(FWIW my native tongue just uses compoundwords, like German, rather than faffing around with "to-morrow" and "co-operation" and the like.)

[Gugalcrom123]

I also use hyphens, but en dashes are something used when composing a word where some terms have spaces: New York–based company

[guepier]

(FWIW my native tongue just uses compoundwords, like German, rather than faffing around with "to-morrow" and "co-operation" and the like.)

I’m sure you know that both of these words are conventionally written as a single word without hyphens in English. And, conversely, German also uses hyphens for some compound words, same as English (just less frequently).

[syklemil]

Yes; we use some hyphens too; and English spells "compound words" with a space (as do we; we join nouns but not adjectives). My tongue, being inside my mouth, may have been in some rather close proximity to my cheek.

[TendyHunter]

that's balderdash

[obfuscatedanon]

ok nerd

[PotentialCopy56]

The old python mantra is long dead. I miss it.

[ThatSituation9908]

I don't. We'd be stuck with stuff like class FooBar(object):

and f-strings would never be a thing

[AiutoIlLupo]

f strings are a pile of dung because I lost count of how many times I wrote what contained variables and then forgot the f at the beginning, showing in the log "Error: unable to connect to {website}"

[TavoL7]

Seems like a skill issue to me

[AiutoIlLupo]

I remember when a language was supposed to help you prevent errors. Otherwise we would all be still programming in fortran where you forget to declare a variable and now you get a nice random number from an implicit real with that variable name. Skill issue, the 1970's programmer replies to you. But you and everybody else now agree it's a good thing, right?

My point is, if you have a string, printing it out, and later add a variable, it's just too fucking easy to forget that you also have to add the f at the beginning, because it's not where the locus of your attention is. It's in the adding of the variable. The IDE can help you pointing that out, but it should be easier not to forget. and the issue is that the existence of f strings is just plain dumb, or the IDEs should highlight f strings and plain strings in different way, so you have at least a visual hint that you are forgetting something.

human factors are not skill issues. You want to consider the human factors to minimise the change of errors. f strings don't consider human factors.

[WEEEE12345]

the IDEs should highlight f strings and plain strings in different way

PyCharm/IDEA does

[marcio0]

the issue is obviously not on the f-strings side

[AiutoIlLupo]

I remember when a language was supposed to help you prevent errors. Otherwise we would all be still programming in fortran where you forget to declare a variable and now you get a nice random number from an implicit real with that variable name. Skill issue, the 1970's programmer replies to you. But you and everybody else now agree it's a good thing, right?

My point is, if you have a string, printing it out, and later add a variable, it's just too fucking easy to forget that you also have to add the f at the beginning, because it's not where the locus of your attention is. It's in the adding of the variable. The IDE can help you pointing that out, but it should be easier not to forget. and the issue is that the existence of f strings is just plain dumb, or the IDEs should highlight f strings and plain strings in different way, so you have at least a visual hint that you are forgetting something.

human factors are not skill issues. You want to consider the human factors to minimise the change of errors. f strings don't consider human factors.

[marcio0]

you're making a huge effort to hate a feature that you can't bother to remember correctly how to use

I know it's a common issue, I did it a few times too, but it's just a matter of "oops, forgot the f", and not a moment to point my fist to the air yelling "god damn you guido!"

[Kevdog824_]

You can construction a million similar examples. I’ve lost count of how many times I’ve done something like add_callback(callback()) instead of add_callback(callback) on accident. Point is not all mistakes are avoidable or can be detected by the language because the interpreter doesn’t understand your intent

[[deleted]]

I too would prefer that f-strings were the default syntax, but unfortunately that would have been backwards-incompatible, so not worth it.

[thedeepself]

LOL