Re: Rationale behind constructor call chain... ( and comparison with C++)



On Oct 30, 9:56 pm, "A.B." <a...@xxxxxxxxxxxxxxx> wrote:
Just a question...

If an object B extends an object A, whenever B is constructed, A is
constructed... if A() calls a
function that is overloaded in B, it looks like the overloaded function
is called by the A constructor ...

( In C++ the behavior is always to call the function defined in A when
called within the A constructor, even if the overloaded function is B
is virtual. )

Can someone explain me the rationale behind java's behavior in that
case, how it's useful, more logical etc than the C++ approach... can
this behavior be overriden?

Thanks!

The C++ approach is correct for C++.
The Java(and C#) approach is correct for Java(and C#).

The languages deal with calls to virtual methods during constructor
calls in ways that make sense for those languages.

Its not a question over which is a better way.

In any case, its commonly understood to be 'a bad thing' in all 3
languages.

The 'Effective C++ book warns against it', see Chapter 2, Item 9: Never
call virtual functions during construction or destruction. page 48.

The same is true for Java and C# (but I can't google a good source for
you to see).

On the other hand, here's a Java RFI that was rejected....with
reasons...

http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4378291

Regards

Andrew

.

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