Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c++ > #15427 > unrolled thread

super superclass

Back to article view | Back to comp.lang.c++

Contents

  super superclass bob@coolfone.comze.com - 2012-04-17 06:50 -0700
    Re: super superclass Marc <marc.glisse@gmail.com> - 2012-04-17 14:29 +0000
    Re: super superclass Christopher Pisz <someone@somewhere.net> - 2012-04-18 16:04 -0500
      Re: super superclass Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-04-18 22:07 +0000
        Re: super superclass Nobody <nobody@nowhere.com> - 2012-04-19 18:40 +0100
          Re: super superclass Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-04-20 07:56 +0000
    Re: super superclass Pavel <pauldontspamtolk@removeyourself.dontspam.yahoo> - 2012-04-20 00:29 -0400

#15427 — super superclass

In C++, is there a class like the Java Object class that all classes derive from?

[toc] | [next] | [standalone]

#15429

bob@coolfone.comze.com wrote:

> In C++, is there a class like the Java Object class that all classes
> derive from?

No.

Now depending on what you want to use Object for, there may still be
ways to accomplish it.

[toc] | [prev] | [next] | [standalone]

#15458

On 4/17/2012 8:50 AM, bob@coolfone.comze.com wrote:
> In C++, is there a class like the Java Object class that all classes derive from?


I've seen a good number of people coming from java that decided to roll 
their own in C++, and more times then not, it ends up causing problems.

Instead, decide what you need a particular class to do, or group of 
classes. You are in the danger zone when you start thinking along the 
lines of "All classes should do X."

For example, do all classes really need a ToString() method? Surely, 
there are going to be some classes where a string representation either 
makes no sense or has little value. However, it might make sense to have 
some common method like ToXml() for all configuration classes....

[toc] | [prev] | [next] | [standalone]

#15459

On Wed, 2012-04-18, Christopher Pisz wrote:
> On 4/17/2012 8:50 AM, bob@coolfone.comze.com wrote:
>> In C++, is there a class like the Java Object class
>> that all classes derive from?
>
> I've seen a good number of people coming from java that decided to roll 
> their own in C++, and more times then not, it ends up causing problems.

That's what Stroustrup calls "don't use C++ as if it was Smalltalk",
and he's warned against it countless times.

(We don't know why the OP asked, though. He didn't say he wanted to
use such a design.)

...
> For example, do all classes really need a ToString() method? Surely, 
> there are going to be some classes where a string representation either 
> makes no sense or has little value.

Unfortunate example, since the standard way to do this in C++ is to
provide a ostream << Foo overload.  No common superclass needed.

> However, it might make sense to have 
> some common method like ToXml() for all configuration classes....

/Jorgen

-- 
  // Jorgen Grahn <grahn@  Oo  o.   .     .
\X/     snipabacken.se>   O  o   .

[toc] | [prev] | [next] | [standalone]

#15473

On Wed, 18 Apr 2012 22:07:47 +0000, Jorgen Grahn wrote:

>> For example, do all classes really need a ToString() method? Surely,
>> there are going to be some classes where a string representation either
>> makes no sense or has little value.
> 
> Unfortunate example, since the standard way to do this in C++ is to
> provide a ostream << Foo overload.  No common superclass needed.

But that will dispatch according to the static (compile-time) type, not
the dynamic (run-time) type.

[toc] | [prev] | [next] | [standalone]

#15489

On Thu, 2012-04-19, Nobody wrote:
> On Wed, 18 Apr 2012 22:07:47 +0000, Jorgen Grahn wrote:
>
>>> For example, do all classes really need a ToString() method? Surely,
>>> there are going to be some classes where a string representation either
>>> makes no sense or has little value.
>> 
>> Unfortunate example, since the standard way to do this in C++ is to
>> provide a ostream << Foo overload.  No common superclass needed.
>
> But that will dispatch according to the static (compile-time) type, not
> the dynamic (run-time) type.

Yes, but is that a problem? It just has to be implemented differently
for those types:

  std::ostream& operator<< (std::ostream& os, const SomeSuperClass& val)
  {
      return val.put(os);
  }

/Jorgen

-- 
  // Jorgen Grahn <grahn@  Oo  o.   .     .
\X/     snipabacken.se>   O  o   .

[toc] | [prev] | [next] | [standalone]

#15485

bob@coolfone.comze.com wrote:
> In C++, is there a class like the Java Object class that all classes derive from?

Technically, no.. but Qt's QObject comes close :-).

See http://qt-project.org/doc/qt-4.8/qobject.html#details.

HTH
Pavel

[toc] | [prev] | [standalone]

Back to top | Article view | comp.lang.c++

csiph-web