The meaning of a = b in object oriented languages

[John W. Kennedy]

Russell Wallace wrote:
> Summercool wrote:
>> so most or all object oriented language do assignment by reference?
>> is there any object oriented language actually do assignment by
>> value?  I kind of remember in C++, if you do
>>
>> Animal a, b;
>>
>> a = b will actually be assignment by value.
>> while in Java, Python, and Ruby, there are all assignment by
>> reference.  ("set by reference")
>>
>> Is that the case: if a is an object, then b = a is only copying the
>> reference?
> 
> Yes, your understanding is exactly correct; C++ will assign by value 
> unless you explicitly use pointers, but the other languages will assign 
> by reference (except for primitive types).

Ada also assigns by value absent explicit use of access variables 
(similar to pointers or references).

The question, in fact, is meaningless. Java has a certain defined 
behavior. C++ has a certain defined behavior. Smalltalk has a certain 
defined behavior. LISP has a certain defined behavior. Ada has a certain 
defined behavior. Object-oriented languages as a class do not.
-- 
John W. Kennedy
"The poor have sometimes objected to being governed badly; the rich have 
always objected to being governed at all."
   -- G. K. Chesterton.  "The Man Who Was Thursday"