Objects aren’t passed at all. By default, the argument is evaluated and its value is passed, by value, as the initial value of the parameter of the method you’re calling. Now the important point is that the value is a reference for reference types – a way of getting to an object (or null). Changes … Read more
My understanding is that this is actually very simple: Javascript is always pass by value, but when a variable refers to an object (including arrays), the “value” is a reference to the object. Changing the value of a variable never changes the underlying primitive or object, it just points the variable to a new primitive or object. However, changing … Read more
Types of Things in Swift The rule is: Class instances are reference types (i.e. your reference to a class instance is effectively a pointer) Functions are reference types Everything else is a value type; “everything else” simply means instances of structs and instances of enums, because that’s all there is in Swift. Arrays and strings are struct instances, for example. You can pass … Read more
Primitives are passed by value, and Objects are passed by “copy of a reference”. Specifically, when you pass an object (or array) you are (invisibly) passing a reference to that object, and it is possible to modify the contents of that object, but if you attempt to overwrite the reference it will not affect the copy of … Read more
Primitives are passed by value, and Objects are passed by “copy of a reference”. Specifically, when you pass an object (or array) you are (invisibly) passing a reference to that object, and it is possible to modify the contents of that object, but if you attempt to overwrite the reference it will not affect the copy of … Read more
Java is always pass-by-value. Unfortunately, when we deal with objects we are really dealing with object-handles called references which are passed-by-value as well. This terminology and semantics easily confuse many beginners. It goes like this: In the example above aDog.getName() will still return “Max”. The value aDog within main is not changed in the function foo with the Dog “Fifi” as the object reference is passed by value. If it … Read more
There are questions that already deal with the difference between passing by reference and passing by value. In essence, passing an argument by value to a function means that the function will have its own copy of the argument – its value is copied. Modifying that copy will not modify the original object. However, when passing by reference, … Read more
I always thought Java uses pass-by-reference. However, I’ve seen a blog post that claims that Java uses pass-by-value. I don’t think I understand the distinction they’re making. What is the explanation?
First and foremost, the “pass by value vs. pass by reference” distinction as defined in the CS theory is now obsolete because the technique originally defined as “pass by reference” has since fallen out of favor and is seldom used now.1 Newer languages2 tend to use a different (but similar) pair of techniques to achieve the same effects (see below) which … Read more