Your class is not immutable strictly speaking, it is only effectively immutable. To make it immutable, you need to use final: private final String name; private final String age; Although the difference might seem subtle, it can make a significant difference in a multi-threaded context. An immutable class is inherently thread-safe, an effectively immutable class … Read more
Yes, HotSpot JIT can eliminate redundant allocations in a local context. This optimization is provided by the Escape Analysis enabled since JDK 6u23. It is often confused with on-stack allocation, but in fact it is much more powerful, since it allows not only to allocate objects on stack, but to eliminate allocation altogether by replacing … Read more
Objects in hashsets should either be immutable, or you need to exercise discipline in not changing them after they’ve been used in a hashset (or hashmap). In practice I’ve rarely found this to be a problem – I rarely find myself needing to use complex objects as keys or set elements, and when I do … Read more
Supposedly we have a general class of Node and class LinkedList based on the above allowing the user to add, remove etc. Now, how would we ensure immutability? You ensure immutability by making every field of the object readonly, and ensuring that every object referred to by one of those readonly fields is also an … Read more
In situations like that, I usually go with Concat. That usually implies to me that a new object is being created. var p = listA.Concat(listB); var k = listA.Concat(item);
The best explanation I ever read is here: http://python.net/~goodger/projects/pycon/2007/idiomatic/handout.html#other-languages-have-variables
Arrays Create immutable array First way: let array = NSArray(array: [“First”,”Second”,”Third”]) Second way: let array = [“First”,”Second”,”Third”] Create mutable array var array = [“First”,”Second”,”Third”] Append object to array array.append(“Forth”) Dictionaries Create immutable dictionary let dictionary = [“Item 1”: “description”, “Item 2”: “description”] Create mutable dictionary var dictionary = [“Item 1”: “description”, “Item 2”: “description”] Append … Read more
In Rust, the compiler stops at the function call boundary when evaluating generic parameters, which includes generic lifetime parameters. In your case 1, you are calling a method: fn get_qux(&mut self) -> &mut Qux { &mut self.qux } This function indicates that all of self will be borrowed mutably, and that the returned reference will … Read more
As of TypeScript 2.8, this is now possible and actually an example in the PR for Conditional Types: https://github.com/Microsoft/TypeScript/pull/21316 Also see the notes on type inference for Conditional Types: https://github.com/Microsoft/TypeScript/pull/21496 I modified the example slightly to use the type inference for the readonly array value type because I find (infer R)[] clearer than Array<T[number]> but … Read more
When you receive a string, you’ll be sure that it stays the same. Suppose that you’d construct a Foo as below with a string argument, and would then modify the string; then the Foo‘s name would suddenly change: class Foo(object): def __init__(self, name): self.name = name name = “Hello” foo = Foo(name) name[0] = “J” … Read more