[okmjuhb]

This is not at all correct because passing by reference and value have defined and distinct meanings. Consider the difference between C++, which has actual pass by reference: void swap(int& x, int& y) { int t = x; x = y; y = t; }, and Java: void swap(Integer x, Integer y) { Integer t = x, x = y; y = t; }. The C++ version will result in changes to the variables in the calling function and the Java version will not.

The real problem is that Java created needless confusion by calling its pointers references for purely marketing reasons.

[binaryfinery]

No the real problem is that you fail to understand that Java gets to call these things what ever it likes because language has context. And your example fails to compare apples to apples. In Java Integer is an object, but int is not. You are confusing Java things with C++ things. As you can see, Java is not C++, and so your C++ terms and definitions do not apply here. Thank you for playing. Move along.

[okmjuhb]

"No the real problem is that you fail to understand that Java gets to call these things what ever it likes because language has context."

This is silly; "pointer" and "reference" both had meanings before Java came along. If Java called pointers "names" instead of "references" it wouldn't mean that its function call semantics were pass-by-name either. And besides; if your argument is that we should use the Java terminology to describe all the aspects of Java under discussion, the fact that the all the Java designers make explicit that the function call semantics pass references as values, not objects as values.

"And your example fails to compare apples to apples. In Java Integer is an object, but int is not. You are confusing Java things with C++ things."

The argument applies if you use int in place of Integer just the same; or if you make a C++ Integer wrapper class analogous to the Java one. Any comparison here will of course be apples to oranges because C++ supports pass by reference and Java does not. The swap function is impossible to write in Java because it requires allowing called functions to change the values viewed in the caller, which is almost the definition of passing arguments by value.

"As you can see, Java is not C++, and so your C++ terms and definitions do not apply here. Thank you for playing. Move along."

Leaving aside the childish and insulting tone, the definition of "pass by reference" has nothing to do with C++; if the code were in perl it would still be pass by reference, because "pass by reference" has a meaning that exists outside of any particular programming language and describes a concept. Java function calls are not part of that concept; "there is exactly one parameter passing mode in Java - pass by value".

[binaryfinery]

In which case there is no such thing as passing by reference. Ever. In C++ when you "pass by reference", what actually happens is that the address of the thing is taken, and a pointer is generated, and then that pointer is passed by value. Do you see? Any argument you put forth to the contrary will involve language specific features and conventions of C++. Your will have to claim that because the C++ compiler does this for you, that makes it special. In Java there are primitives and objects. Primitives are only passed by value. Objects are passed by reference. If you pass an object as a parameter, and then modify a property of the parameter, then it is the original object that is modified. This, in fact, is the same as when you pass an Object in C++ by reference. In contrast, in C++ you can also pass an object by value: the entire object is copied onto the stack.

class Foo; void modify( Foo& x) { x.setBar(1);} ; <- pass by reference in C++.

class Foo; void modify( Foo x) { x.setBar(1);} ; <- pass by reference in Java.

Java spares you the & because Java only passes by reference.

Again, to argue the contrary, simply because it passes an object pointer by value, automatically, is to argue that C++ never passes by reference because it too takes the address automatically.

The fact is that Java passes by reference exactly as C++ does. However, even if this were not the case, it would also be completely acceptable for Java to refer to what it does as pass by reference simply because it chooses too. These things are object references. If I pass a java object reference, is it acceptable to say I'm passing by reference? If Java people want to say it is, then it is. Will the world end, for example, because the word "heap" means two different things in computer science? http://en.wikipedia.org/wiki/Heap OMG! Who is right?

My point is basically summed up here: http://xkcd.com/435/

You are where the physicist is standing. You insist that Java biologists are using your terms wrong while oblivious to the mathematician. You have your abstractions. Java has theirs.

Of course, maybe you're the chemist, and I'm the physicist (I still write assembly) and the hardware guys are the mathematicians. Whatever.

As for the insulting tone, yes its a character flaw. When someone makes a statement like "I'm really tired of hearing folks (incorrectly) state [whatever]", its insulting. Its especially insulting when its wrong. In an ideal world I'd be able to respond without resorting to responding in kind, but I'm flawed. Sorry. You're still wrong.

[okmjuhb]

The argument "well, passing by reference gets compiled to passing a pointer by value so really there is no passing by reference" is silly because passing by reference is a description of language semantics and function call evaluation. Your argument applies just as well to the statements "there is no such thing as lambda functions" or "there is no such thing as garbage collection" because those language features also get converted into representations that don't have either of them present.

The Java code you give isn't an example of passing by reference because, while you can change the value that x points to in Java, you can't change x to point to something different. No java function can change its arguments; the example you gave has the java function changing something that its argument points to.

Your argument that Java people can call language features the same name as distinct language features is: a. dumb, because it's just "words mean whatever anyone wants them to mean", and b. doesn't come anywhere close to applying here; the quotation at the end of my last response: "there is exactly one parameter passing mode in Java - pass by value" is a direct quote from 'The Java Programming Language'. The authors of Java disagree with you.

More from them: "All parameters to methods are passed 'by value'. In other words, values of parameter variables in a method are copies of the values the invoker specified as arguments. If you pass a double to a method, its parameter is a copy of whatever value was being passed as an argument, and the method can change its parameter's value without affecting values in the code that invoked the method.

...

You should note that when the parameter is an object reference, it is the object reference - not the object itself - that is passed "by value." Thus, you can change which object a parameter refers to inside the method without affecting the reference that was passed. But if you change any fields of the object or invoke methods that change the object's state, the object is changed for every part of the program that holds a reference to it.

...

Some people will say incorrectly that objects are passed "by reference." In programming language design, the term pass by reference properly means that when an argument is passed to a function, the invoked function gets a reference to the original value, not a copy of its value. If the function modifies its parameter, the value in the calling code will be changed because the argument and parameter use the same slot in memory.

...

The Java programming language does not pass objects by reference; it passes object references by value. Because two copies of the same reference refer to the same actual object, changes made through one reference variable are visible through the other. There is exactly one parameter passing mode - pass-by-value - and that helps keep things simple."

Your last few paragraphs are beside the point; the question is not about which languages offer which levels of abstraction; the point is that different abstractions have different names and Java doesn't offer the abstraction named "pass by reference".

[binaryfinery]

Perhaps I misunderstand the whole thing then. Tell me is this C++ code "pass by reference" or not?

class Foo;

void Bar( Foo& somefoo) { ... }