namespace detection

Question

I'm trying to write a log library which would use an external tool

To make the library more natural to use, i would like to be able to detect the namespace in which cout is used.

concretly the result should be used like this

namespace A
{
    void foo()
    {
          cout << "Something went very wrong" << endl;
    }
}

namespace B
{
    void bar()
    {
          cout << "C should equal 3" << endl;
    }
}

int main()
{
    B::bar();
    A::foo();
}

and the resulting output should look like this

MODULE::B : C should equal 3
MODULE::A : Something went very wrong

I already use std::streambuf to add certain keywords to the output of cout, all i need to be able to do is specify which streambuf to use in which namespace.

How do i achieve this?

Also the library i'm making is to be integrated in a project with multiple namespaces which making heavy uses of the using namespace declaration. I would need a solution which will not require to remove these declarations.

edit1: i don't care having to specify by hand which namespace is associated with which string or adding objects to any of the used namespaces (except std of course)

Isn't the compiler already telling you that something is wrong with `A::bar()` and `B::foo()`? — Andy Prowl, Apr 09 '13 at 12:38
Possible duplicate - http://stackoverflow.com/q/10657711/2065121 — Roger Rowland, Apr 09 '13 at 12:39
@RogerRowland in this case i'm specifically interested in the answer specific to `std::cout` which i thought would lead to more conflicts than normal — tiridactil, Apr 09 '13 at 12:45
`which making heavy uses of the using namespace declaration` My commiserations. — Lightness Races in Orbit, Apr 09 '13 at 12:46

score 2 · Accepted Answer · answered Apr 09 '13 at 12:46

2

How about creating your custom logger stream? That way the user can specify the component that failed, like so:

namespace A {
    void foo()
    {
          log("A") << "Something went very wrong" << endl;
    }
}

namespace B {
    void bar()
    {
          log("B") << "C should equal 3" << endl;
    }
}

int main()
{
    B::bar();
    A::foo();
}

Perhaps less automagical, but __FILE__ macro could also give some information.

answered Apr 09 '13 at 12:46

Bartek Banachewicz

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adding a specific logger would do exaclty what i'm trying to achieve but has one flaw i was trying to work around which is that i would need to find and change any existing cout in order to prevent moduleless logs – tiridactil Apr 09 '13 at 12:49
1

`#defining` `cout` into something else might be the only option then. – Bartek Banachewicz Apr 09 '13 at 12:51
1

While I would not like to `#define` `cout` as a long term solution, you can use it to detect the uses of it and you can remove the define after you have changed that for your particular logging. – David Rodríguez - dribeas Apr 09 '13 at 12:56

score 1 · Answer 2 · answered Apr 09 '13 at 12:43

1

This is not possible in the language. If you are using Clang you could recompile Clang to perform such a task for you.

answered Apr 09 '13 at 12:43

Puppy

144,682
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465

score 1 · Answer 3 · answered Apr 09 '13 at 12:45

1

you may try to inject function like std::string namespace_name() in every namespace you want to show up, and then call std::cout << namespace_name() would lead most inner namespace name output

answered Apr 09 '13 at 12:45

kassak

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namespace detection

3 Answers3