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What's New in C# 14: Null-Conditional Assignments

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Re: What's New in C# 14: Null-Conditional Assignments

#121

Post by DeathArrow »

Metasyntactic wrote: post #120
DeathArrow wrote: post #79

While this is nice, there are some long requested features like Discriminated Unions that got delayed a lot.

Hi there. C# lang designer here :) Discriminated unions continue to be worked on, and you can see our latest designs here: https://github.com/dotnet/csharplang/blob/main/proposals/uni... The space there is large and complex, and we have a large amount of resources devoted to it. There was no way that `a?.b = c` was going to change if/when unions come to the language. For unions, nothing has actually been delayed. We…

Thank you for working on it, I hope we will see it in a release soon.

By delayed I mean that the committee was discussing about discriminated unions since a long time ago and it was never "the right time". You can see the discussions related to implementing discriminated unions on Github.

Re: What's New in C# 14: Null-Conditional Assignments

#122

Post by klysm »

Metasyntactic wrote: post #105
maltalex wrote: post #71

Cute, but is this actually needed? It's one more thing to remember, one more thing to know the subtleties of, and for what? To save writing a very readable and unambiguous line of code? It feels like the C# designers have a hard time saying "no" to ideas coming their way. It's one of my biggest annoyances with this otherwise nice language. At this point, C# has over 120 keywords (incl. contextual ones) [0]. This is a…

> Cute, but is this actually needed? It's one more thing to remember, one more thing to know the subtleties of, and for what? Hi there! C# language designer here :-) In this case, it's more that this feature made the language more uniform. We've had `?.` for more than 10 years now, and it worked properly for most expressions except assignment. During that time we got a large amount of feedback from users asking for t…

Thank you for all the hard work on C#! I’ve been loving the past 5 years of developments and don’t agree with the parent comment here.

p.s. I will take the opportunity to say that I dream of the day when C# gets bounded sum types with compiler enforced exhaustive pattern matching. It feels like we are soooo close with records and switch expression, but just missing one or two pieces to make it work.

Re: What's New in C# 14: Null-Conditional Assignments

#123

Post by klysm »

vjvjvjvjghv wrote: post #32

It's starting to feel like C# is going down the path of C++. Tons of features that introduce subtleties and everybody has their own set of pet features they know how to use. But the code gets really hard to understand when you encounter code that uses a subset you aren't familiar with. I remember staring at C++ codebases for days trying to figure out what is going on there. There was nothing wrong with the code. I ju…

This is syntax sugar. Don’t conflate syntactic niceties with the semantic absurdity that C++ has.

Re: What's New in C# 14: Null-Conditional Assignments

#124

Post by johnh-hn »

maltalex wrote: post #71

Cute, but is this actually needed? It's one more thing to remember, one more thing to know the subtleties of, and for what? To save writing a very readable and unambiguous line of code? It feels like the C# designers have a hard time saying "no" to ideas coming their way. It's one of my biggest annoyances with this otherwise nice language. At this point, C# has over 120 keywords (incl. contextual ones) [0]. This is a…

I went to the .NET Developer Conference (NDC) in London at the beginning of the year. Mads Torgersen (Lead C# Designer, for anyone not in the know) gave a talk about some new proposed features. After describing a proposal to introduce new syntax to make defining extension methods easier, he asked if anyone had any questions. I asked a question along the lines of:

"I understand we sometimes need to address deficiencies in a language, but when we do stop? More syntax is leading to daily decision fatigue where it's difficult to justify one approach over another. I don't want C# to become C++."

It was interesting listening to the discussion that took over from that. The audience seemed in favour of what I said, and someone else in the audience proposed a rolling cut-off to deprecate older features after X years. It sounded very much like Mads had that discussion internally, but Microsoft weren't in favour. I understand why, but the increasing complexity of the language isn't going to help any of us long-term.

Re: What's New in C# 14: Null-Conditional Assignments

#125

Post by cemdervis »

pjmlp wrote: post #111
peterashford wrote: post #47

I'm a Java fan so I'm contractually required to dis c#, but actually I kinda like this. It reduces boilerplate. Yes, it could be abused but this is what code review is for.

Why the requirement, because of J++ and how Ext-VOS alongside Cool became .NET? Most companies don't care about this kind of stuff. I work across Java, C#, JS/TS, C++, SQL, and whatever else might be needed, even stuff like Go and C, that I routinely criticise, because there is my opinion, and then there is the job market, and I rather pay my bills.

Reminds of something I read somewhere: "I don't love Java, but I love the house it bought me."

Re: What's New in C# 14: Null-Conditional Assignments

#126

Post by fifticon »

To add to the chorus, IMHO this is a jumping-the-shark language feature. Having the problem this feature addresses, is a code smell. I use the ?-indexer for READING stuff, but try to limit such uses to logging and diagnostics, where they shouldn't affect actual production effects.

If your C# code needs this, your "C# code" is 3 javascript files in a trenchcoat.. :-).

Re: What's New in C# 14: Null-Conditional Assignments

#127

Post by Metasyntactic »

klysm wrote: post #122
Metasyntactic wrote: post #105

Earlier quoted context omitted.

> Cute, but is this actually needed? It's one more thing to remember, one more thing to know the subtleties of, and for what? Hi there! C# language designer here :-) In this case, it's more that this feature made the language more uniform. We've had `?.` for more than 10 years now, and it worked properly for most expressions except assignment. During that time we got a large amount of feedback from users asking for t…

Thank you for all the hard work on C#! I’ve been loving the past 5 years of developments and don’t agree with the parent comment here. p.s. I will take the opportunity to say that I dream of the day when C# gets bounded sum types with compiler enforced exhaustive pattern matching. It feels like we are soooo close with records and switch expression, but just missing one or two pieces to make it work.

Thanks @klysm! I think we're getting close to that. `unions` are a big part of this discussion, and we're working very hard to hopefully get them in soon :)

Re: What's New in C# 14: Null-Conditional Assignments

#128

Post by Metasyntactic »

DeathArrow wrote: post #121
Metasyntactic wrote: post #120

Earlier quoted context omitted.

Hi there. C# lang designer here :) Discriminated unions continue to be worked on, and you can see our latest designs here: https://github.com/dotnet/csharplang/blob/main/proposals/uni... The space there is large and complex, and we have a large amount of resources devoted to it. There was no way that `a?.b = c` was going to change if/when unions come to the language. For unions, nothing has actually been delayed. We…

Thank you for working on it, I hope we will see it in a release soon. By delayed I mean that the committee was discussing about discriminated unions since a long time ago and it was never "the right time". You can see the discussions related to implementing discriminated unions on Github.

Hard problems take time :)

They also often need a lot of scaffolding to be built along the way. We like breaking hard problems into much smaller, composable, units that we can build into the language and then compose to a final full solution. We've been doing that for many years, with unions being a major goal we've been leading to. At this point, we think we have the right pieces in place to naturally add this in a way that feels right to the C# ecosystem.

Thanks for the feedback!

Re: What's New in C# 14: Null-Conditional Assignments

#129

Post by Metasyntactic »

bandyaboot wrote: post #31

I’m having a hard time imagining where this is useful. If I’m trying to assign to a property, but encounter an intermediate null value in the access chain, just skipping the assignment is almost never going to be what I want to do. I’m going to want to initialize that null value.

Hi there, one of the lang designers here :)

Think of it this way. We already supported these semantics in existing syntax through things like invocations (which are freely allowed to mutate/write). So `x?.SetSomething(e1)`. We want properties to feel and behave similarly to methods (after all, they're just methods under the covers), but these sorts of deviations end up making that not the case.

In this situation, we felt like we were actually reducing concept count by removing yet another way that properties don't compose as well with other language features as something like invocation calls do.

Note: when we make these features we do do an examination of the ecosystem and we can see how useful the feature would be. We also are community continuously with our community and seeing just how desirable such a feature is. This goes beyond just those who participate on the open source design site. But also tons of private partners, as well as tens of thousands of developers participating at our conferences and other events.

This feature had been a continued thorn for many, and we received continuous feedback in the decade since `?.` was introduced about this. We are very cautious on adding features. But in this case, given the continued feedback, positive reception from huge swaths of the ecosystem, minimal costs, lowered complexity, and increased consistency in the language, this felt like a very reasonable change to make.

Thanks!

Re: What's New in C# 14: Null-Conditional Assignments

#130

Post by Metasyntactic »

rkagerer wrote: post #14

More concise? Yes. More readable? I'm less convinced on that one. Some of those edge cases and their effects can get pretty nuanced. I fear this will get overused exactly as the article warns, and I'm going to see bloody questions marks all over codebases. I hope in time the mental overhead to interpret exactly what they're doing will become muscle memory...

Hi there! Lang designer here.

> More concise? Yes.

Note: being more concise is not really the goal of the `?` features. The goal is actually to be more correct and clear. A core problem these features help avoid is the unfortunate situation people need to be in with null checks where they either do:

    if (some_expr != null)
        someExpr...
Or, the more correct, but much more unweildy:

    var temp = some_expr;
    if (temp != null)
        temp...
`?` allows the collapsing of all the concepts together. The computation is only performed once, and the check and subsequent operation on it only happens when it is non-null.

Note that this is not a speculative concern. Codebases have shipped with real bugs because people opted for the former form versus the latter.

Our goal is to make it so that the most correct form should feel the nicest to write and maintain. Some languages opt for making the user continuously write out verbose patterns over and over again to do this, but we actually view that as a negative (you are welcome to disagree of course). We think forcing users into unweildy patterns everywhere ends up increasing the noise of the program and decreasing the signal. Having common patterns fade away, and now be more correct (and often more performant) is what we as primary purposes of the language in the first place.

Thanks!

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