nameLabel.text = user?.name ?? "Guest"
if let name = user?.name {
nameLabel.text = name
} else {
nameLabel.text = "Guest"
}In some languages, you simply write:
if (user)
nameLabel.text = user.name;
else
nameLabel.text = "Guest";
nameLabel.text = user.name if user else "Guest"
When constructing objects "in-line" in c# I actually used to see the ternary operator quite a lot, as in
new SomeClass() {
Val = valSource == null? SomeClass.DefaultVal : valSource
}
How the hell is it worse? It lets me write things like
toolbar.visibility = userSettings.showToolbar ?? defaultSettings.showToolbar
someOption = localPreference ?? onlinePreference ?? defaultPreference
Giving the developer succinct ways to prevent program failure from unexpectedly undefined values is a feature.
> It's called the "if" clause.
If we got rid of everything we don't absolutely need in programming, we would have to get rid of 98% of Swift syntax, and probably every modern programming language including Swift.
I started off with machine language, in embedded systems. You can't get much more "raw" than that.
I have been writing Swift exclusively for a long time. I speak it without an accent. It's my beauty.
But I also know that you can have so much sugar you fall into a diabetic coma.
Exactly my feelings. Same thing here started from machine code and now doing everything else including kitchen sink
Type in a bunch of numbers, then set the PC to 0.
Assembler was great after that.
I do not remember that stuff fondly. It sucked.
"If" is often a statement, not an expression, so they aren't equivalent in a lot of cases. I'm not sure if this is the case in Swift, but I'm fairly certain that Swift's '?' operator also does unwrapping and propagation, similar to '?' in Rust.
int a = b ?: c ?: 0I hate it when things like this get names that everyone's supposed to know and it's considered a mark against you if you've never heard it before, but I do think the name Elvis Operator is hilarious. :D
> The name "Elvis operator" refers to the fact that when its common notation, ?:, is viewed sideways, it resembles an emoticon of Elvis Presley.
b = list.next.to_s || "Reached end of list."
a = b || c || 0
edit: One BIG downside to this I forgot to mention at first: If nil and a false value are both possible for a variable, then this construction can betray you and break your heart.
Personally, I like the ternary operator, and I also like the nil-coalescing operator, but I'm quite aware that they can produce difficult-to-maintain code, so I'm careful with them. I have gone and done some silly stuff with both, but then, I realized that I was leaving unmaintainable code.
If you use godbolt.org, you can actually see what code is produced by the source.
int a = b ?: c;
In Swift, this is expressed by "??".
It means "If the previous test returns nil, then execute what is after the ??".
For example, if you have a concrete Int, but the source might be an optional, then you could do something like this:
That means that if b is nil, then set a to 0. Otherwise, set it to whatever value b has.You can chain these, like so:
So you have a couple of optional values coming in, but they could be nil, so you chain them.You can have a lot more going on in the handlers than simple assignments, but this gives you an idea.