The meaning of a = b in object oriented languages

[Ken Bloom]

On Tue, 18 Sep 2007 18:02:59 -0400, Lew wrote:

> Summercool wrote:
>> when a writing or a book reads "a is a Hash object; a is an Array
>> object; or a is an Animal object" it is just a short form to say that
>> "a is a reference to that object."
>> 
>> b = a means "whatever a is referencing to, now b is referencing it
>> too".
>> 
>> so that's why  a[1] = "foobar"  will change what b will display, but a
>> = "foobar" will not change what b will display.
> 
> You can't do both in Java.  Is a an array or a String?  If a is a String
> and b is an array, then neither `a = b' nor `b = a' will compile in
> Java.
> 
> Java is a strongly-typed, compiled language which means it does more
> static type checking and thus would reject treating a as both an array
> and a String.
>   In that environment the programmer must choose one or the other.

In this Java example, a and b are statically typed to be of type Object. 
Both Strings and Arrays descend from Object. (And primatives like 
integers and the like will be autoboxed into descendants of Object).




-- 
Ken Bloom. PhD candidate. Linguistic Cognition Laboratory.
Department of Computer Science. Illinois Institute of Technology.
http://www.iit.edu/~kbloom1/