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Groups > comp.lang.java.programmer > #36934

Re: How to assign an object to another in it method?

From Arne Vajhøj <arne@vajhoej.dk>
Newsgroups comp.lang.java.programmer
Subject Re: How to assign an object to another in it method?
Date 2017-07-14 14:40 -0400
Organization Aioe.org NNTP Server
Message-ID <okb37k$l8q$1@gioia.aioe.org> (permalink)
References (21 earlier) <ok63ib$krk$1@jstuckle.eternal-september.org> <slrnomehsu.o2q.avl@logic.at> <ok7vjd$uef$1@jstuckle.eternal-september.org> <slrnomfb4t.o2q.avl@logic.at> <okaq5e$6et$1@jstuckle.eternal-september.org>

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On 7/14/2017 12:10 PM, Jerry Stuckle wrote:
> On 7/13/2017 1:19 PM, Andreas Leitgeb wrote:
>> I don't like the non-polymorphic default values of C++, but I do like that
>> in C++ a subclass *can* get rid of its inherited baggage.
> 
> Interesting - I hadn't run into this before (probably because I don't
> use a lot of default arguments in virtual functions).  It did take some
> looking but I finally found the part of the standard which covers this:
> 
> In 11.3.6 Paragraph 10:
> 
> "A virtual function call (13.3) uses the default arguments in the
> declaration of the virtual function determined by the static type of the
> pointer or reference denoting the object. An overriding function in a
> derived class does not acquire default arguments from the function it
> overrides."
> 
> The more I think of this the more sense it makes (although I don't like
> it).  Default arguments are inserted at compile time, not run time.  So
> it would have to use the static type of the pointer or reference.  I do
> think it should be possible to make that determination at runtime,
> though.

It may be worth noting that C# does it the same way.

using System;

namespace E
{
     public class P
     {
         public virtual void Foo(int v = 123)
         {
             Console.WriteLine(v);
         }
     }
     public class C : P
     {
         public override void Foo(int v = 456)
         {
             base.Foo(v);
         }
     }
     public class Program
     {
         public static void Main(string[] args)
         {
             P o1 = new C();
             o1.Foo();
             C o2 = new C();
             o2.Foo();
             Console.ReadKey();
         }
     }
}

outputs:

123
456

Arne

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Thread

How to assign an object to another in it method? parmenides <xparmenides@yahoo.com> - 2017-06-18 20:02 +0800
  Re: How to assign an object to another in it method? Eric Sosman <esosman@comcast-dot-net.invalid> - 2017-06-18 08:09 -0400
  Re: How to assign an object to another in it method? Robert Klemme <shortcutter@googlemail.com> - 2017-06-18 15:31 +0200
  Re: How to assign an object to another in it method? Eric Sosman <esosman@comcast-dot-net.invalid> - 2017-06-19 10:22 -0400
    Re: How to assign an object to another in it method? Eric Douglas <e.d.programmer@gmail.com> - 2017-06-19 08:13 -0700
      Re: How to assign an object to another in it method? Eric Sosman <esosman@comcast-dot-net.invalid> - 2017-06-19 11:53 -0400
        Re: How to assign an object to another in it method? Eric Douglas <e.d.programmer@gmail.com> - 2017-06-19 09:06 -0700
          Re: How to assign an object to another in it method? Eric Sosman <esosman@comcast-dot-net.invalid> - 2017-06-19 13:56 -0400
      Re: How to assign an object to another in it method? lewbloch@gmail.com - 2017-06-27 13:49 -0700
        Re: How to assign an object to another in it method? Andreas Leitgeb <avl@logic.at> - 2017-06-28 12:20 +0000
          Re: How to assign an object to another in it method? Eric Douglas <e.d.programmer@gmail.com> - 2017-06-28 05:51 -0700
            Re: How to assign an object to another in it method? Eric Sosman <esosman@comcast-dot-net.invalid> - 2017-06-28 14:03 -0400
            Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-02 21:23 -0400
              Re: How to assign an object to another in it method? Martin Gregorie <martin@address-in-sig.invalid> - 2017-07-03 10:59 +0000
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-03 08:38 -0400
                Re: How to assign an object to another in it method? Andreas Leitgeb <avl@logic.at> - 2017-07-03 14:04 +0000
                Re: How to assign an object to another in it method? Jerry Stuckle <jstucklex@attglobal.net> - 2017-07-03 10:39 -0400
                Re: How to assign an object to another in it method? Andreas Leitgeb <avl@logic.at> - 2017-07-03 16:28 +0000
                Re: How to assign an object to another in it method? Jerry Stuckle <jstucklex@attglobal.net> - 2017-07-03 16:52 -0400
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-03 22:04 -0400
                Re: How to assign an object to another in it method? Jerry Stuckle <jstucklex@attglobal.net> - 2017-07-03 23:15 -0400
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-04 21:46 -0400
                Re: How to assign an object to another in it method? Jerry Stuckle <jstucklex@attglobal.net> - 2017-07-04 22:18 -0400
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-08 21:13 -0400
                Re: How to assign an object to another in it method? Jerry Stuckle <jstucklex@attglobal.net> - 2017-07-08 22:12 -0400
                Re: How to assign an object to another in it method? Andreas Leitgeb <avl@logic.at> - 2017-07-11 17:56 +0000
                Re: How to assign an object to another in it method? Jerry Stuckle <jstucklex@attglobal.net> - 2017-07-11 15:40 -0400
                Re: How to assign an object to another in it method? Eric Douglas <e.d.programmer@gmail.com> - 2017-07-11 13:49 -0700
                Re: How to assign an object to another in it method? Jerry Stuckle <jstucklex@attglobal.net> - 2017-07-11 17:41 -0400
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-11 20:27 -0400
                Re: How to assign an object to another in it method? Jerry Stuckle <jstucklex@attglobal.net> - 2017-07-11 21:43 -0400
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-11 21:49 -0400
                Re: How to assign an object to another in it method? Jerry Stuckle <jstucklex@attglobal.net> - 2017-07-12 17:20 -0400
                Re: How to assign an object to another in it method? Andreas Leitgeb <avl@logic.at> - 2017-07-13 10:08 +0000
                Re: How to assign an object to another in it method? Martin Gregorie <martin@address-in-sig.invalid> - 2017-07-13 11:35 +0000
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-13 08:14 -0400
                Re: How to assign an object to another in it method? Martin Gregorie <martin@address-in-sig.invalid> - 2017-07-13 14:29 +0000
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-13 13:47 -0400
                Re: How to assign an object to another in it method? Andreas Leitgeb <avl@logic.at> - 2017-07-13 18:09 +0000
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-13 15:01 -0400
                Re: How to assign an object to another in it method? Andreas Leitgeb <avl@logic.at> - 2017-07-13 19:19 +0000
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-13 15:39 -0400
                Re: How to assign an object to another in it method? Andreas Leitgeb <avl@logic.at> - 2017-07-13 16:49 +0000
                Re: How to assign an object to another in it method? Jerry Stuckle <jstucklex@attglobal.net> - 2017-07-13 10:24 -0400
                Re: How to assign an object to another in it method? Andreas Leitgeb <avl@logic.at> - 2017-07-13 17:19 +0000
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-13 21:17 -0400
                Re: How to assign an object to another in it method? Andreas Leitgeb <avl@logic.at> - 2017-07-14 06:40 +0000
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-14 14:26 -0400
                Re: How to assign an object to another in it method? Andreas Leitgeb <avl@logic.at> - 2017-07-15 14:36 +0000
                Re: How to assign an object to another in it method? Jerry Stuckle <jstucklex@attglobal.net> - 2017-07-14 12:10 -0400
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-14 14:40 -0400
                Re: How to assign an object to another in it method? Jerry Stuckle <jstucklex@attglobal.net> - 2017-07-14 14:51 -0400
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-14 21:05 -0400
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-14 21:06 -0400
                Re: How to assign an object to another in it method? lewbloch@gmail.com - 2017-07-14 14:44 -0700
                Re: How to assign an object to another in it method? Andreas Leitgeb <avl@logic.at> - 2017-07-12 16:23 +0000
                Re: How to assign an object to another in it method? Eric Douglas <e.d.programmer@gmail.com> - 2017-07-12 10:12 -0700
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-11 20:16 -0400
                Re: How to assign an object to another in it method? Jerry Stuckle <jstucklex@attglobal.net> - 2017-07-11 21:46 -0400
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-11 21:52 -0400
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-11 20:24 -0400
                Re: How to assign an object to another in it method? Jerry Stuckle <jstucklex@attglobal.net> - 2017-07-11 21:49 -0400
                Re: How to assign an object to another in it method? Arne Vajhøj <arne@vajhoej.dk> - 2017-07-11 21:55 -0400
                Re: How to assign an object to another in it method? Martin Gregorie <martin@address-in-sig.invalid> - 2017-07-03 12:37 +0000
                Re: How to assign an object to another in it method? Eric Sosman <esosman@comcast-dot-net.invalid> - 2017-07-03 11:34 -0400
                Re: How to assign an object to another in it method? Martin Gregorie <martin@address-in-sig.invalid> - 2017-07-03 17:28 +0000
  Re: How to assign an object to another in it method? v_borchert@despammed.com (Volker Borchert) - 2017-06-19 17:13 +0000
  Re: How to assign an object to another in it method? Eric Douglas <e.d.programmer@gmail.com> - 2017-06-19 13:40 -0700

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