Namespaces

[Marcin Vorbrodt]

Here is an example of my code:

//Header file
#include <vector>
using std::vector;

namespace Revelation {
// class definitions, etc...
// class members are of type std::vector
}
//Source File
#include <header_file>
namespace Revelation {
// stuff that used std::vector here;
}

Now my question is: where should I put the #include<vector >, and where
should I put using std::vector ??? Both outside of my namespace? Include
outside and "using" inside? Both inside?

Thanks,
Martin

[Alf P. Steinbach]

On Sat, 6 Sep 2003 01:20:47 -0400, "Marcin Vorbrodt" <mv*****@eos.nc su.edu> wrote:

Here is an example of my code:

//Header file
#include <vector>
OK.

using std::vector;
Don't do that in a header file.
namespace Revelation {
// class definitions, etc...
// class members are of type std::vector
}
//Source File
#include <header_file>
namespace Revelation {
// stuff that used std::vector here;
}

Now my question is: where should I put the #include<vector >,
OK as is.

and where should I put using std::vector ???

Not in the header file.

Before the code that uses 'std::vector' unqualified.

[Marcin Vorbrodt]

Let me be more specific...
Should the #unclude and using be inside my namespace or before it?

Martin

"Alf P. Steinbach" <al***@start.no > wrote in message
news:3f******** ********@News.C IS.DFN.DE...

On Sat, 6 Sep 2003 01:20:47 -0400, "Marcin Vorbrodt" <mv*****@eos.nc su.edu> wrote:

Here is an example of my code:

//Header file
#include <vector>

OK.

using std::vector;

Don't do that in a header file.

namespace Revelation {
// class definitions, etc...
// class members are of type std::vector
}
//Source File
#include <header_file>
namespace Revelation {
// stuff that used std::vector here;
}

Now my question is: where should I put the #include<vector >,

OK as is.

and where should I put using std::vector ???

Not in the header file.

Before the code that uses 'std::vector' unqualified.

[Alf P. Steinbach]

On Sat, 6 Sep 2003 02:00:04 -0400, "Marcin Vorbrodt" <mv*****@eos.nc su.edu> wrote:

Answer: Because it messes up the order in which people normally read text.

Question: Why is top-posting such a bad thing?

Answer: Top-posting.

Question: What is the most annoying thing on Usenet?

Let me be more specific...
Should the #unclude and using be inside my namespace or before it?

Martin

"Alf P. Steinbach" <al***@start.no > wrote in message
news:3f******* *********@News. CIS.DFN.DE...

On Sat, 6 Sep 2003 01:20:47 -0400, "Marcin Vorbrodt"

<mv*****@eos.n csu.edu> wrote:

>Here is an example of my code:
>
>//Header file
>#include <vector>

OK.

>using std::vector;

Don't do that in a header file.

>namespace Revelation {
> // class definitions, etc...
> // class members are of type std::vector
>}
>
>
>//Source File
>#include <header_file>
>namespace Revelation {
> // stuff that used std::vector here;
>}
>
>Now my question is: where should I put the #include<vector >,

OK as is.

> and where should I put using std::vector ???

Not in the header file.

Before the code that uses 'std::vector' unqualified.

[Marcin Vorbrodt]

OK...

"Alf P. Steinbach" <al***@start.no > wrote in message
news:3f******** ********@News.C IS.DFN.DE...

On Sat, 6 Sep 2003 02:00:04 -0400, "Marcin Vorbrodt" <mv*****@eos.nc su.edu> wrote:
Answer: Because it messes up the order in which people normally read text.
Question: Why is top-posting such a bad thing?

Answer: Top-posting.

Question: What is the most annoying thing on Usenet?

Let me be more specific...
Should the #unclude and using be inside my namespace or before it?

Martin

"Alf P. Steinbach" <al***@start.no > wrote in message
news:3f******* *********@News. CIS.DFN.DE...

On Sat, 6 Sep 2003 01:20:47 -0400, "Marcin Vorbrodt"

<mv*****@eos.n csu.edu> wrote:

>Here is an example of my code:
>
>//Header file
>#include <vector>

OK.
>using std::vector;

Don't do that in a header file.

>namespace Revelation {
> // class definitions, etc...
> // class members are of type std::vector
>}
>
>
>//Source File
>#include <header_file>
>namespace Revelation {
> // stuff that used std::vector here;
>}
>
>Now my question is: where should I put the #include<vector >,

OK as is.
> and where should I put using std::vector ???

Not in the header file.

Before the code that uses 'std::vector' unqualified.

[Kevin Goodsell]

Marcin Vorbrodt wrote:

OK...

Please don't top-post. It is bad Usenet etiquette. Re-read section 5 of
the FAQ for posting guidelines. You seem to have missed some points the
first time through.

http://www.parashift.com/c++-faq-lite/

-Kevin
--
My email address is valid, but changes periodically.
To contact me please use the address from a recent posting.

[Peter van Merkerk]

> <Marcin Vorbrodt>

" <mv*****@eos.nc su.edu> wrote in message

Now my question is: where should I put the #include<vector >, and where
should I put using std::vector ??? Both outside of my namespace? Include
outside and "using" inside? Both inside? </Marcin Vorbrodt>

Namespace is a fairly useless feature since you drag
all names back into the global namespace before you
can use them. With some extra typing and an extra
level of bugs.

The fact that you don't understand namespaces doesn't make them useless.
The only good thing about namespace is the global
namespace :: It makes you feel like you are 'inside
an object' when programming.

If you sincerely believe that is a good advice, you better stay far away
from large scale C++ projects and stick with "hello world" type of
applications. Considering that many programming languages offer a feature
similar to C++ namespaces should ring a bell though.

--
Peter van Merkerk
peter.van.merke rk(at)dse.nl

[Agent Mulder]

<Agent Mulder>

The one good thing about namespace is the global
namespace :: It makes you feel like you are 'inside
an object' when programming. </Agent Mulder>

<Peter van Merkerk> If you sincerely believe that is a good advice, you better stay far away
from large scale C++ projects and stick with "hello world" type of
applications. Considering that many programming languages offer a feature
similar to C++ namespaces should ring a bell though.

</Peter van Merkerk>

Why not declare a class LargeScaleC++Pr oject with pointers
to (named) MiddleScaleC++P roject objects? With proper
design there is no need for namespace. If such thing were
introduced at all, it had been better to add file level support.

-X

[Mike Wahler]

Agent Mulder <mb************ *******@home.nl > wrote in message
news:bj******** **@news2.tilbu1 .nb.home.nl...

<Marcin Vorbrodt>
" <mv*****@eos.nc su.edu> wrote in message

Now my question is: where should I put the #include<vector >, and where
should I put using std::vector ??? Both outside of my namespace? Include
outside and "using" inside? Both inside? </Marcin Vorbrodt>

Namespace is a fairly useless feature

Nonsense.
since you drag
all names back into the global namespace before you
can use them.

// the following uses a single name from namesspace
// 'std'. It puts no names at all in the 'global
// namespace' except the function name 'foo()'

#include <iostream>

void foo()
{
using std::cout;
cout << "you don't understand namespaces\n";
}
The following puts all names from namespace 'std'
in the scope of function 'foo()', and puts no names
in 'global scope' except the function name 'foo()'

#include <iostream>

void foo()
{
using namespace std;
cout << "you need to read about namespaces in a C++ book\n";
}

With some extra typing
One cannot use a language feature without expressing it.
This is done by typing. How else?
and an extra
level of bugs.
What level of bugs? You mean those that are introduced
by folks who don't understand namespaces?

The only good thing about namespace is the global
namespace ::
What's good about it?
It makes you feel like you are 'inside
an object' when programming.

And that's good because? What does it feel like to
be 'inside an object?'

-Mike

[Peter van Merkerk]

> <Agent Mulder>

The one good thing about namespace is the global
namespace :: It makes you feel like you are 'inside
an object' when programming. </Agent Mulder>

<Peter van Merkerk>

If you sincerely believe that is a good advice, you better stay far away
from large scale C++ projects and stick with "hello world" type of
applications. Considering that many programming languages offer a feature similar to C++ namespaces should ring a bell though.

</Peter van Merkerk>

Why not declare a class LargeScaleC++Pr oject with pointers
to (named) MiddleScaleC++P roject objects?

If you have to ask that you are really clueless about namespaces and even
more so about large scale projects. Classes and namespaces address two very
different issues. A class LargeScaleC++Pr oject with pointers to
MiddleScaleC++P roject objects (to which instances are they pointing too???)
does something totally different than namespaces. It seems that you don't
know the difference between declaration and instantiation. In the days
namespaces were not commonly supported by C++ compilers sometimes a struct
was used to emulate namespaces (but not in the way you describe). However
that struct hack was a long trek from the real thing.
With proper
design there is no need for namespace.
This has little to do with design. But if you never go beyond "hello world"
type applications namespaces are indeed a useless feature.
If such thing were
introduced at all, it had been better to add file level support.

I don't know what you mean by that (it could mean just about anything), but
I guess the standardization commitee should invite you to their next
meeting.

--
Peter van Merkerk
peter.van.merke rk(at)dse.nl