Erik Wikström wrote: >> their reference (alias) mechanism. And C, Python, and Ruby probably >> won't let you do that. What about Java and Perl? > > C will let you do it with pointers (it is just a syntactical difference > from references in this case) and Java's references allows it.
Neither C or Java has call by reference. C pointers and Java references may work similarly in most cases but it is still call by value. > I do not > know about Ruby, Python and Perl, but (AFAIK) the all have OO support so > I would be surprised if they used purely value semantics. I can not see why OO should indicate anything about call by reference support. >> isn't "what i pass in, the function can modify it" not a desireable >> behavior if i am NOT passing in the address of my argument? For one > > Being able to pass the actual object instead of a copy is highly > desirable for two reasons. In most languages only one return value is > allowed for a function so the ability to change parameters allows you to > artificially return more without having to wrap them in constructs. The > second reason is that for large objects the performance hit of having to > create a copy each time you call a function can be forbidding. Usually it is not a good thing, because it makes the code much more difficult to read. But sometimes it is handy. I think C# got it right. It allows it but require an explicit marking of it in both formal argument list and actual argument list. >> Java, Python, and Ruby, and we pass in a reference to object (not C+ >> +'s meaning of alias reference) > > In what way does the C++ reference differ from those in Java, Python, > and Ruby in this situation? C++ and Java are very different in this aspect. Arne -- http://mail.python.org/mailman/listinfo/python-list
