alt Hacker NewsFalse dichotomy. The problem is that the syntax implements a solution that is likely wrong in many situations and pairs with a bad program design. Maybe when we have this:
what?.could?.possibly.go?.wrong = important_value()
if (!what)
what = new typeof(what); // default-construct representative instance
if (!what.could)
what.could = new typeof(what.could);
if (!what.could.possibly.go)
what.could.possibly.go = new typeof(what.could.posssibly.go)
// now assignment can take place and actually retain the stored value
// since we may have allocated what, we have to be sure
// we propagate it out of here.
what.could.possibly.go.wrong = important_value();
Why would you ever write an assignment, but not expect that it "sticks"? Assignments are pretty important.
What if someone doesn't notice the question marks and proceeds to read the rest of the code thinking that the assignment always takes effect? Is that still readable?
Replies
NullReferenceException, in line 7.
you didn't null check possibly.go.
Just because you can't do assignments like that, it doesn't mean you shouldn't use null coalescing for reads. What exactly could go wrong?
I wonder, does the important_value function get called and the value discarded or never called at all? Looks like a footgun if it has side-effects.
> Maybe we want code like this
It should be clear enough that this operator isn't going to run 'new' on your behalf. For layers you want to leave missing, use "?.". For layers you want to construct, use "??=".
> Why would you ever write an assignment, but not expect that it "sticks"? Assignments are pretty important.
If you start with the assignment, then it's important and you want it to go somewhere.
If you start with the variable, then if that variable doesn't have a home you don't need to assign it anything.
So whether you want to skip it depends on the situation.
> What if someone doesn't notice the question marks and proceeds to read the rest of the code thinking that the assignment always takes effect? Is that still readable?
Do you have the same objection with the existing null-conditional operators? Looking at the operators is important and I don't think this makes the "I didn't notice that operator" problem worse in a significant way.