Is this a good convention for namespaces?

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?
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
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.
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.
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.
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
Duthomhas (13281)
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