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Is this a good convention for namespaces?

Apr 30, 2012 at 5:33pm
Miles Lacey (5)
Hello,
I was trying to experiment with some functional programming on a small-scale project and was wondering if my current namespace convention was good practice.

Basically, I declare a set of functions under a namespace in a header file:
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namespace listOfFunctions {
     void initialize();
     void cleanup();
     int foo();
     int bar();
}


I then define them in the corresponding source file. Now in some cases, there are some static variables that these functions should share. So in the source file, I put these variables in an anonymous namespace so that they can't be modified elsewhere.

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namespace {
     int var1;
     int var2;
}

namespace listOfFunctions {
     void initialize() {
          //initialize var1 & var 2
     }

     void cleanup() {
          //free var1 & var 2 resources
     }

     int foo() {
          //use var1 & var 2
     }

     int bar() {
          //use var1 & var 2
     }
}


My question is, since I want to avoid using classes and singletons, I thought this would be a safer way to have a set of global functions, but is it good style/convention?
Apr 30, 2012 at 5:55pm
hanst99 (2869)
I guess you can program functional style in C++ if you try hard enough (I did try recently, and it worked semi-well for small things) - but why bother?

EDIT: Looking at your pseudocode, you don't actually use functional style at all. So what were you actually going to ask?
Last edited on Apr 30, 2012 at 5:57pm
Apr 30, 2012 at 6:16pm
kbw (9488)
That's sort of what namespaces are for, to provide a scope for declarations. You do realise you can nest namespaces too, right?

But don't go for fine grain control, a namespace per library is enough, and that namespace can be further subdivided. But always consider how a user might call your code. Aim for concise simplicity. STL is a good reference example.
Apr 30, 2012 at 6:28pm
Miles Lacey (5)
Thanks kbw, I just wasn't sure. Good to know that I can nest namespaces. That should at least clean up the clutter I made.
Apr 30, 2012 at 6:57pm
JLBorges (13770)
I tend to organize my namespaces this way:

header file:
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namespace parser
{
    namespace version_1
    {
        class ast { /* .... */ } ;
        std::shared_ptr<ast> parse( const std::string& ) ;
        // ...
    }

    // declare names required by inline implementations, the parser test driver etc.
    namespace _detail_ 
    {
        // .....
    }

    using namespace version_1 ;

}


Implementation file:
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namespace parser
{
    namespace version_1
    {
        namespace // names programmatically not visible outside
        {
            // ....
        }

        namespace _detail_ // names required by external implementation helpers
        {
            // .....
        }

        std::shared_ptr<ast> parse( const std::string& )
        {
            // ...
        }

        // ...

    }
}


// Using it:
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int main()
{
    auto tree = parser::parse( "whatever.txt" ) ; // parser::version_1::parse today
                                            // may be parser::version_2::parse tomorrow

    auto tree2 = parser::version_1::parse( "whatever.txt" ) ; // always version_1
}


Note: Use C++11 inline namespaces instead, when they become widely supported.
Apr 30, 2012 at 7:21pm
bluecoder (763)
I am not able to understand any thing .... may be because i am too tierd .. and need some sleep .. but request you all there to be more simple .. so that i can understand it .
thanks in advance
xx
Apr 30, 2012 at 7:39pm
Duthomhas (13251)
Topic archived. No new replies allowed.