C# is getting “?.”, sometimes called the Safe Navigation Operator (opens in new tab)

(blogs.msdn.com)

27 pointsmendicant12y ago10 comments

10 comments

8 comments · 2 top-level

mendicantOP12y ago· 6 in thread

The question I have about this: Does making it easy to do parent?.child?.grandchild?.property help or hinder the software development process in the long term?

_random_12y ago

This will help getting rid of the Maybe monad pattern in our code (at least partially) - all patterns are patches for missing language features. I cannot see any drawbacks personally. Would much rather prefer the 'object! paramName' not-null enforcement operator though, but it is tricky to make it backwards-compatible.

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vorg12y ago

The ?. has only really worked in scripting, i.e. writing quick scripts to manipulate code written in a proper type-checked programming language. Groovy has it but Java doesn't. In Groovy's heyday if some code spewed out NullPointerException, the first thing people did was replace all the . with ?. and run it again, because the code was throwable quality anyway. I can't imagine anything good will come of putting ?. into C# (or Java) which is meant for building more lasting systems.

gizmo68612y ago

Using ?. lets you do code like:

    var = foo()?.bar?.bing()
    if(foo==null){...}

instead of putting a null check between every call. In many cases null is used to indicate that a computation failed. If you are doing a chain of computations, there is often not a reason you need or want to do a check between every computation, instead of having a single handler at the end for if any of them fail.

This pattern comes up fairly often in Haskell, which accomplishes it with the Maybe monad.

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mcv12y ago

Groovy is used for very serious websites, just like Java. And in Java, maintainability, and therefore readability, of code is just as important as in Groovy. I really like the ?. operator, and I miss it in Java. It makes code cleaner, more robust, and easier to check. Less boilerplate, more readability.

mendicantOP12y ago

I can understand the reason for it being there, but I also tend to fall towards following the Law of Demeter. I tend to find that most (not all) of the use cases of this are a symptom of overly intimate knowledge between objects that really shouldn't know about one another.

bpicolo12y ago

It currently exists in Coffeescript (and I'm sure other languages). Always been handy.

mcv12y ago

Great news. The ?. operator in Groovy greatly reduces boilerplate code and improves readability and maintainability. No layers of null pointer checks that are all basically the same and getting in the way of what you actually want to do.

And in those cases where you still need specific behaviour based on which object is null, you can still use the . operator with traditional null pointer checks.

j / k navigate · click thread line to collapse

10 comments

8 comments · 2 top-level

mendicantOP12y ago· 6 in thread

The question I have about this: Does making it easy to do parent?.child?.grandchild?.property help or hinder the software development process in the long term?

_random_12y ago

1 more reply

vorg12y ago

gizmo68612y ago

Using ?. lets you do code like:

    var = foo()?.bar?.bing()
    if(foo==null){...}

This pattern comes up fairly often in Haskell, which accomplishes it with the Maybe monad.

1 more reply

mcv12y ago

mendicantOP12y ago

bpicolo12y ago

It currently exists in Coffeescript (and I'm sure other languages). Always been handy.

mcv12y ago

And in those cases where you still need specific behaviour based on which object is null, you can still use the . operator with traditional null pointer checks.

j / k navigate · click thread line to collapse