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Home » Developing U++ » U++ Developers corner » [REJECTED]: VarArgs class for U++ (va_ macros replacement, in U++ stlye)
[REJECTED]: VarArgs class for U++ (va_ macros replacement, in U++ stlye) [message #46030] Sun, 21 February 2016 14:46 Go to previous message
Oblivion is currently offline  Oblivion
Messages: 585
Registered: August 2007
Location: Turkey
Contributor
Hello guys,

While SSH package is on its way, I would like to share some part of its code which might be in general a useful addition to U++.

VarArgs class is a special type of container, eliminating the need for C style variadic functions and related va_xxx macros. It can contain any type of argument in an orderly fashion, and allows dynamic manipulation of the arguments list.


This class was actually an integral part of my AsyncQueue class (a simple yet extremely flexible, generic synchronization tool for writing single-threaded, non-blocking apps/components in a uniform way, inspired by existing solutions in U++ framework) which I use building SSH package and will give you more information in the following days.

Below is the entire interface of the class:

class VarArgs : Moveable<VarArgs> {
    Vector<Any> args;
public:
    template<class T> VarArgs&  Add(const T& t)                 { args.Add().Create<T>() = t; return *this; }
    template<class T> VarArgs&  operator<<(const T& t)          { return Add(t); }
    template<class T> T&        Set(int i, const T& t)          { T& arg = args[i]; arg = t; return arg; }  
    template<class T> T&        Insert(int i, const T& t)       { return args.Insert(i, t); }
    template<class T> T&        Get(int i)                      { ASSERT(Is<T>(i)); return args[i].Get<T>(); }
    inline void                 Remove(int i)                   { args.Remove(i); }
    inline int                  GetCount() const                { return args.GetCount(); }
    inline void                 Clear()                         { args.Clear(); }
    template<class T> bool      Is(int i) const                 { args[i].Is<T>(); }
    inline bool                 IsEmpty() const                 { return args.IsEmpty(); }
    inline bool                 IsPicked() const                { return args.IsPicked(); }     
    
    VarArgs()                   {}
    virtual ~VarArgs()          {}
};




I added a very simple example to the package to show what this class is capable of:

#include <Core/Core.h>
#include <VarArgs/VarArgs.h>

using namespace Upp;

String str_cpp = "This is a demonstration of the VarArgs class of C++!";

bool PrintNumberViaGate(int i) 
{
    Cout() << "Number printed via gate: " << i << "\r\n";
    return false;
}
void Foo(VarArgs& va) 
{
    Cout() << va.Get<int>(0) << "\r\n";
    Cout() << va.Get<float>(1) << "\r\n";
    Cout() << va.Get<String>(2) << "\r\n";

    String* str_upp = va.Get<String*>(3);
    str_upp->Set(str_upp->ReverseFind('C'), 'U');
    Cout() << str_cpp << "\r\n";

    Gate1<int> cb = va.Get<Gate1<int> >(4);
    cb(9999);
}

CONSOLE_APP_MAIN
{
    Foo(VarArgs() << 10 << 22.33f << String("Hello World!") << &str_cpp << callback(PrintNumberViaGate));
//  Same thing can be done via explicit calls.
//  VarArgs va;
//  va  .Add(10)
//      .Add(22.33f)
//      .Add(String("Hello World!"))
//      .Add(&str_cpp)
//      .Add(callback(PrintNumberViaGate));
//  Foo(va);    

}




Mirek, in case you find it useful, please feel free to modify and/or add it to the Core package. If you you reject it, I'd like to upload it to the Bazaar section.

Any suggestions, bug reports and criticism are welcome.

(Tested under Linux (ArchLinux) with GCC 5.3.4)

Regards,
Oblivion




[Updated on: Thu, 25 February 2016 21:36]

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