Personally, this feels like a feature that is too focused on one problem to be a general feature. Python is getting huge. When people ask me if Python is easy and simple to learn I have to say "the basics, yes, but to to learn the whole language... not so much".
I feel like in this sense Go really is interesting by rejecting almost every single feature. Honestly not sure generics were worth it as they add a lot of complexity, and while they are nice, I don't need them very much. The general idea to keep the language at its original focus is the right idea IMO. C++ would be the most extreme case where the language itself barely resembles what it started out as.
Python has always been a batteries-included language, so having a go at templated string interpolation —a feature other languages have had for decades— seems like a strange gripe.
It's far more essential than little utilities like textwrap or goliath packages like Python's bundled tkinter implementation.
C# InterpolatedString is very close, with the twisty bit being that C# can rely on static typing for safety so the "f-string" and "t-string" variants use the same literal syntax and depend on what function they are passed to, whereas in both Python and Javascript they have different literal syntaxes. Python chose to use a different literal prefix to its literals ("f" versus "t") and Javascript chose to use a function-call syntax as prefix (`templateString` versus html`templateString` where html is a function in scope).
For the case like here it’s closer to FormattableString that’s what EF Core’s composable FromSql method works on top of. Both address custom interpolation but from different angles / for different scenarios.
Also, you can also find languages like Python that have a rich ecosystem of third party templating solutions. These are often intended for things like rendering entire web pages but many of them have relatively simple ways of using their templating functionality in a fairly reasonable amount of code, if you just want to have a template format that allows interpolating values based on a template string.
So, as you can see, many other languages have this feature, as you can tell from all the examples I have shown you here.
(To spell it out for those who may find this too subtle... somehow... I'm not a fan of this simply because Python has gone from "There should be one-- and preferably only one --obvious way to do it." to "there's half-a-dozen ways to do it and if they are all wrong Python 3.x+1 will introduce a seventh" and I'm just not seeing the benefits worth the tradeoffs here.)
I find this a confusing reply. First, you seem to be confusing eager string interpolation with this lazy/deferred templating feature. I'm specifically asking about languages that have the latter. More confusingly, you bring up the language under discussion as an example... if it already had this feature, they wouldn't be adding a new feature.
Then, you bring up 3rd party templating solutions, but this is off topic, as we are talking about language builtins. I am well aware there are many templating solutions to solve text templating in general.
In summary, I'm specifically asking for examples of languages that allow string interpolation with _deferred/lazy_ processing, which is how I understand this feature. It seems there are a few, but it doesn't seem to be terribly common after reading the other comments.
It's not confusing... it's sarcastic. I don't believe adding literally a third string interpolation method to a language is generally justified, and honestly you can consider it a fourth if you think, as I do, that even "my string " + val + " etc." is itself an interpolation language, especially when combined with things like __str__. I'm afraid you fed me a straight line I couldn't resist; it's not really an answer to you.
If I were in charge of Python, I'd probably feature-freeze it. It is already too large, but shrinking it is impractical.
Failing that, because it probably would fail, I would be raising the bar sky-high on new feature additions.
It seems like the project has actually lowered the bar in the last few versions. What was once one of my favorite languages, if not my favorite, is now a language I try to avoid, and approaching one I actively recommend against. When I'm writing it myself it's ok, but using other people's code in it is getting harder and harder, as they keep using all the features.
This is a pretty simple and useful feature. I wouldn’t say that it bloats the language too much. Descriptors and metaclasses are much more complicated and have a lot more implications and have been in the language for a veeeeery long time. Is it decades already?
This feature is not complicated, but one must keep every feature that can possibly be seen in code in their head. Even if it is familiar now, what happens when you use the feature in the one small section of code where it fits, nowhere else, and then read that code 2 years later? This is the problem with adding useful features that are only used in a few key places. I'm not saying Go is a perfect language, far from it, but limiting # of features as a general goal is something more languages should strive for IMO.
I am not arguing against that language ideally should have less features. I am arguing with “Python is getting huge”, because it’s huge and has been for many-many years :)
Yeah, Python hasn’t been a simple language for a long time, if ever. That’s probably the biggest misconception about the language - that its friendly syntax implies simple semantics. It’s not true at all.
I would say python in it's entirety is one of, if not the deepest and potentially most complex language I know. C++ is the other contender. The things you could do with metaclasses, multiple inheritance and operator overloading are quite staggering.
I'm just glad you don't have to think or even use this as a normal user of the language, most of the time or at all.
A lot of Python's complexity like descriptors and metaclasses and the so-called cooperative multiple inheritance come from an era where object orientation is gospel and yet people keep finding limitations to what can be accomplished in an OO paradigm and therefore they patch up the language to support ever more complicated use cases.
I have a feeling that if metaclasses and descriptors were to be proposed today it would be laughed out of the PEP process completely.
> I have a feeling that if metaclasses and descriptors were to be proposed today it would be laughed out of the PEP process completely.
I think you need at least one of these. Modern Python eschews metaclasses but descriptors are everywhere. Without them you couldn’t have @classmethod, @staticmethod nor @property - or at least, you couldn’t generalise custom method lookup and all three of those would need to be special cases.
The alternative approach is to drop descriptors and make method lookup much simpler, but then you need metaclasses (see: static methods in Ruby).
If descriptors didn't exist in the language, classmethod, staticmethod, and property would become keywords. Languages like Java and C++ already have static as a keyword; C++ also made its type system have a special pointer to member type; such behavior can be hardcoded without having a flexible descriptor mechanism.
Custom method lookup would just be the same as custom attributes, that is, by the user overriding __getattr__.
I'm truly glad that Go exists for people who like languages that are simple even to the point of frustration and I hope it never changes. But I'm glad that other languages exist for those of us for whom learning some syntax is not a barrier and having convenient ways to do common things is highly valued.
There’s an interesting trade off around maintenance. Python’s stdlib means there’s more consistency across projects and you can assume basic things like error handling which you had to check individually on each Go program, which is the kind of stuff which adds up when you have a lot of small programs.
This is especially noticeable with AWS Lambda where you can have a lot of useful stuff running for years without doing more than bumping the runtime version every year or two, but also that is one highly opinionated architecture so it’s not globally optimal for everyone.
I feel like in this sense Go really is interesting by rejecting almost every single feature. Honestly not sure generics were worth it as they add a lot of complexity, and while they are nice, I don't need them very much. The general idea to keep the language at its original focus is the right idea IMO. C++ would be the most extreme case where the language itself barely resembles what it started out as.