If you’re going to use structs, it is a best practice to make them immutable. Making all the fields readonly is a great way to help (1) document that the struct is immutable, and (2) prevent accidental mutations. However, there is one wrinkle, which actually in a strange coincidence I was planning on blogging about … Read more
Yes. It’s called a tuple. So, instead of [1,2] which is a list and which can be mutated, (1,2) is a tuple and cannot. Further Information: A one-element tuple cannot be instantiated by writing (1), instead, you need to write (1,). This is because the interpreter has various other uses for parentheses. You can also … Read more
What is Immutability? Immutability is applied primarily to objects (strings, arrays, a custom Animal class) Typically, if there is an immutable version of a class, a mutable version is also available. For instance, Objective-C and Cocoa define both an NSString class (immutable) and an NSMutableString class. If an object is immutable, it can’t be changed … Read more
Making integers mutable would be very counter-intuitive to the way we are used to working with them. Consider this code fragment: a = 1 # assign 1 to a b = a+2 # assign 3 to b, leave a at 1 After these assignments are executed we expect a to have the value 1 and … Read more
I would do what you believe is simplest and clearest. If you have a data value class which is only used by a restricted number of classes. esp a package local class. then I would avoid getter/setters and use package local or public fields. If you have a class which you expect other modules/developers to … Read more
As always, the answer is “it depends”. Let’s test native arrays with a million-element array: for (var i = 0; i < arr.length; i++); var len=arr.length; for (var i = 0; i < len; i++); http://josh3736.net/images/arrlen.png Chrome and Firefox optimize the property accessor to be as efficient as copying the length to a local variable. … Read more
You can use map to iterate the data and check for the fieldName, if fieldName is cityId then you need to change the value and return a new object otherwise just return the same object. Write it like this: var data = [ {fieldName: ‘title’, valid: false}, {fieldName: ‘description’, valid: true}, {fieldName: ‘cityId’, valid: false}, … Read more
You can use Object.assign: Object.assign([], array, {2: newItem});
You can map the stride instead of iterating it, that allows to get the result as a constant: let input = [1, 2, 3, 4, 5, 6] let output = stride(from: 0, to: input.count – 1, by: 2).map { (input[$0], input[$0+1]) } print(output) // [(1, 2), (3, 4), (5, 6)] If you only need to … Read more
It means that once you instantiate the object, you can’t change its properties. In your first alert you aren’t changing foo. You’re creating a new string. This is why in your second alert it will show “foo” instead of oo. Does it mean, when calling methods on a string, it will return the modified string, … Read more