Is there anything in C++ akin to Java's class Object?

[Blue Ocean]

The reason why I ask is because I am unfamiliar with the idea of
templates. It seems like it would be easier if all classes that
needed something like

template<class T> class Stack { ... }

could be done with just some generic superclass, instead of using a
template.

If this is not the case, does the reason have something to do with
performance, or is it just an alternative that was not thought of?

[Alf P. Steinbach]

* Blue Ocean:

The reason why I ask is because I am unfamiliar with the idea of
templates. It seems like it would be easier if all classes that
needed something like

template<class T> class Stack { ... }

could be done with just some generic superclass, instead of using a
template.

If this is not the case, does the reason have something to do with
performance, or is it just an alternative that was not thought of?

Templates give static typechecking (at compile+link time).

A common base class gives dynamic typechecking (at run-time).

Static typechecking is superior for producing correct code, _and_
is generally also superior with respect to performance.

One downside is that templates in C++ are not well integrated with
the rest of the language, and are so complex that most compilers
don't support them fully, which in practice means that if you
intend to produce portable code it's not enough to follow the
Holy Standard; the code must tested with and adapted to the various
compilers of interest, and perhaps even be non-standard-conforming.

Another downside is that template code is generally very difficult to
debug and to maintain, so the idea is to code only very general and very
simple things as templates.

--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

[John Harrison]

On 7 Jul 2004 13:19:54 -0700, Blue Ocean <bl*********@ho tmail.com> wrote:

The reason why I ask is because I am unfamiliar with the idea of
templates. It seems like it would be easier if all classes that
needed something like

template<class T> class Stack { ... }

could be done with just some generic superclass, instead of using a
template.
With a generic super class you have to downcast when you retrieve the
object from the Stack. Doing that is either inefficent (if you use
dynamic_cast) or not type safe (if you use static_cast). Either way its
ugly. So I've always thought that this is a weakness of Java.

How many times have you written an application where you wanted to put
anything, literally objects of any type, onto a Stack. Almost always you
have one type or some small set of types in mind, this is what C++ lets
you do.

Why do you think Java's way is easier? I've always thought that they were
forced into generic super classes precisely because they didn't have
templates.

If this is not the case, does the reason have something to do with
performance, or is it just an alternative that was not thought of?

I'm sure it was thought of and rejected. Bjarne Stroupstrup was certainly
familar with Smalltalk, which has a generic superclass just like Java.

[E. Robert Tisdale]

Something that calls itself Blue Ocean wrote:

The reason why I ask is because
I am unfamiliar with the idea of templates.
The obvious solution is to learn something about templates.
It seems like it would be easier if all classes that needed something like

template<class T> class Stack { ... }

could be done with just some generic superclass,
instead of using a template.
It *can* be done with "some generic superclass"
*besides* using templates!
If this is not the case,
does the reason have something to do with performance,
or is it just an alternative that was not thought of?

Class templates are preferred because
compile time optimizations can be applied to templates classes
that cannot be applied to classes with virtual functions.

[Blue Ocean]

"E. Robert Tisdale" <E.************ **@jpl.nasa.gov > wrote in message news:<cc******* ***@nntp1.jpl.n asa.gov>...

[snip]

Troll alert? Don't you think that's a bit harsh? Pardon a newbie for
offending your sensibilities, but please don't jump to conclusions.
My experience is limited, so I came here for advice, not to be
lambasted by someone who can't deal with even a perceived (not real)
challenge to their opinions.

If my wording was a bit off, I'm sorry, but the way you responded was
totally uncalled for. I like C++ better than Java, and I'm not here
to put it down. If I was, I'd think of better ways of doing it than
pretending to be a newbie.

[Blue Ocean]

"John Harrison" <jo************ *@hotmail.com> wrote in message news:<opsasbi8d b212331@androni cus>...

On 7 Jul 2004 13:19:54 -0700, Blue Ocean <bl*********@ho tmail.com> wrote:

[snip]

Thanks for the help. I guess that what the other guy said about how
static type-checking is superior in general is true. Thinking about
it, I can't think of any case in which I would have put objects of two
different types into a collection last semester when I was using Java,
so static type checking would not have made a difference. And if the
performance is better, all the more reason to use it.

[E. Robert Tisdale]

Blue Ocean wrote:

Troll alert? Don't you think that's a bit harsh?
Pardon a newbie for offending your sensibilities,
but please don't jump to conclusions.
My experience is limited, so I came here for advice,
not to be lambasted by someone
who can't deal with even a perceived (not real)
challenge to their opinions.
If my wording was a bit off, I'm sorry,
but the way you responded was totally uncalled for.
It certainly was called for.
I like C++ better than Java, and I'm not here to put it down.
If I was, I'd think of better ways of doing it
than pretending to be a newbie.

You use a troll handle (Blue Ocean) instead of your given name.
You post from a disposable email account (bl*********@ho tmail.com).
Your Java and C++ comparison appears intended to incite a language war.
There is *good* reason to suspect that you are trolling.

[tom_usenet]

On 7 Jul 2004 19:39:13 -0700, ag***********@g mail.com (Blue Ocean)
wrote:

"John Harrison" <jo************ *@hotmail.com> wrote in message news:<opsasbi8d b212331@androni cus>...

On 7 Jul 2004 13:19:54 -0700, Blue Ocean <bl*********@ho tmail.com> wrote:

[snip]

Thanks for the help. I guess that what the other guy said about how
static type-checking is superior in general is true. Thinking about
it, I can't think of any case in which I would have put objects of two
different types into a collection last semester when I was using Java,
so static type checking would not have made a difference. And if the
performance is better, all the more reason to use it.

Java 1.5 (due soon) adds generics to Java, using an implementation
that allows typesafe containers, but doesn't give you a performance
improvement. Better than nothing I suppose.

Tom
--
C++ FAQ: http://www.parashift.com/c++-faq-lite/
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html

[tom_usenet]

On 7 Jul 2004 19:30:31 -0700, ag***********@g mail.com (Blue Ocean)
wrote:

"E. Robert Tisdale" <E.************ **@jpl.nasa.gov > wrote in message news:<cc******* ***@nntp1.jpl.n asa.gov>...

[snip]

Troll alert? Don't you think that's a bit harsh?

Don't worry, his nickname is "Trollsdale "; random "Troll Alert"
postings are his speciality.

Tom
--
C++ FAQ: http://www.parashift.com/c++-faq-lite/
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html

[Blue Ocean]

"E. Robert Tisdale" <E.************ **@jpl.nasa.gov > wrote in message news:<cc******* ***@nntp1.jpl.n asa.gov>...

Blue Ocean wrote:

You use a troll handle (Blue Ocean) instead of your given name.
You post from a disposable email account (bl*********@ho tmail.com).
Your Java and C++ comparison appears intended to incite a language war.
There is *good* reason to suspect that you are trolling.

My given name is James F. Aguilar. I've been trying to get Google to
show it for some time but even if I look, I can't find the place to
change what it displays. Now that I'm using a gmail account, please
understand that this is by no means a disposable e-mail address, since
they are by invite only and come with a lot of nice features that
hotmail doesn't have.

I will attempt to avoid posting Java/C++ comparisons in the future,
unless I absolutely must in order to obtain understanding.