Re: How to do "events"

From:
timor.super@gmail.com
Newsgroups:
comp.lang.c++
Date:
13 Apr 2007 05:15:55 -0700
Message-ID:
<1176466555.149586.219470@w1g2000hsg.googlegroups.com>
Hi,

thanks for your answer,
that looks like very good for me ...
only one thing is missing ... boost :)

I will configure it now

Best regards,

S.

On 13 avr, 13:24, "dasjotre" <dasjo...@googlemail.com> wrote:

On 12 Apr, 14:12, timor.su...@gmail.com wrote:

Hi group,

I would like to simulate something that can be quite similar to
"Events".
I would like that a member function of a class can be "setted" as an
Eventand that this method can be called after something special.
Consider the following example :
I'm setting a function with a pointor function, then in a while-true
block, I ask for an input, if input is "abc", i'm firing anevent
(that prints "abc").

#include <iostream>
#include <string>

.>

using namespace std;

typedef void (*fPtrEvent)();

classEvent
{
private:
        static fPtrEvent fEvent;
public:
       Event() {};
        static void Set(fPtrEvent f)
        {
                fEvent = f;
        }
        void WhileTrue()
        {
                while(1)
                {
                        string s;
                        cin >> s;
                        if (s == "abc" && fEvent != 0)
                                fEvent();
                        if (s == "q")
                                break;
                }
        }

};

fPtrEventEvent::fEvent = 0;

class Test
{
public:
        static void DoPrint()
        {
                cout << "print abc" << endl;
        }

};

int main (void)
{
       Event*c = newEvent();
        c->Set(&Test::DoPrint);
        c->WhileTrue();
        delete c;
        return 0;

}


for more general solution check boost::signals library
it is a type safe callback library
you can also check battle tested libsigc++
which does the same think in almost the
same way as boost::signals
#include <iostream>
#include <string>

#include <boost/signals.hpp>
#include <boost/bind.hpp>

(you spend most of your time designing
your program, typing five extra characters
should not be such a chore. Injecting whole
of std into your namespace is never a good
idea)
//using namespace std;

classEvent
{
        ::boost::signal<void()> sig_;
public:

    template<class Fun>
        ::boost::signals::connection connect(Fun fun)
        {
                return sig_.connect(fun);
        }

        void WhileTrue()
        {
                std::string s;
                do
                {
                    std::cin >> s;
                        if (s == "abc")
                            // call all connected
                        sig_();

                }while(s != "q");
        }

};

class Test
{
public:

        void DoPrint()
        {
                std::cout << "Test\n";
        }

};

void Test1()
{
        std::cout << "Test1\n";

}

int main()
{
       Eventc;
        Test t;
        // connect non static member function
        c.connect(boost::bind(&Test::DoPrint, &t));
        // connect non member function
        c.connect(&Test1);
        c.WhileTrue();
        return 0;

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