In Python a variable is not a box that holds things, it is a name that points to an object. In your code: d = { ‘m’: [1,2,3] } –> binds the name d to a dictionary m = d[‘m’] –> binds the name m to a list m = m[1:] –> binds the name … Read more
Normally a temporary object (such as one returned by a function call) has a lifetime that extends to the end of the “enclosing expression”. However, a temporary bound to a reference generally has it’s lifetime ‘promoted’ to the lifetime of the reference (which may or may not be the lifetime of the calling function), but … Read more
A compiler vendor would typically implement a reference as a pointer. Pointers tend to be the same size as or larger than many of the built-in types. For these built-in types the same amount of data would be passed whether you passed by value or by reference. In the function, in order to get the … Read more
As Rytmis said, Java passes references by value. What this means is that you can legitimately call mutating methods on the parameters of a method, but you cannot reassign them and expect the value to propagate. Example: private void goodChangeDog(Dog dog) { dog.setColor(Color.BLACK); // works as expected! } private void badChangeDog(Dog dog) { dog = … Read more
What are you doing in your method? If you’re merely populating an existing array, then you don’t need pass-by-reference semantics – either in .NET or in Java. In both cases, the reference will be passed by value – so changes to the object will be visible by the caller. That’s like telling someone the address … Read more
are you required to use the & modifier to pass-by-reference? Technically/semantically, the answer is yes, even with objects. This is because there are two ways to pass/assign an object: by reference or by identifier. When a function declaration contains an &, as in: function func(&$obj) {} The argument will be passed by reference, no matter … Read more
In general, using a non const reference like Ref<T>& is never a good idea because this will only work if the caller already has a Ref<T> object at hand. This discards 5 and 7. The cases 3 and 4 does not make sense, and they won’t compile in general. Then, there is not much difference … Read more
If you mean to pass a value (so the function doesn’t modify it), there is no reason to pass it by reference : it will only make your code harder to understand, as people will think “this function could modify what I will pass to it — oh, it doesn’t modify it?“ In the example … Read more
Yes, use a closure: functionName($someArgument, function() use(&$variable) { $variable = “something”; }); Note that in order for you to be able to modify $variable and retrieve the modified value outside of the scope of the anonymous function, it must be referenced in the closure using &.