EWOL: Object message

Table of Contents

• Objectifs:
• Message system
• Receive signals from other object
• Declare Signal:
• Conclusion:

Constructor MyObj() { // nothing to do.. } void init() { ewol::Object::init(); m_button = ewol::widget::Button::create(); if (m_button == nullptr) { APPL_ERROR("Can not create button..."); return; } m_button->propertyToggle.set(true); // We connect signals here: (permanent connection) m_button->signalUp.connect(sharedFromThis(), &appl::MyObj::onCallbackUp); m_button->signalValue.connect(sharedFromThis(), &appl::MyObj::onCallbackValue); } public: //!

Objectifs:

• Understand base of e-signal Messaging system
• Create extern message and receive Object message

Message system

esignal base his signal on landa functions

It permit to an object to generate some **'signals'**

All signal are synchronous *(asynchronous is not implemented yet)*

Receive signals from other object

Register on the 'up' and 'value' signal of a button:

Button header :

...
public:
    esignal::Signal<> signalDown;
    esignal::Signal<> signalUp;
    ...
    esignal::Signal<bool> signalValue;
...

simple signal connection:

#include <ewol/object/Object.hpp>
#include <ewol/widget/Button.hpp>
namespace appl {
    class MyObj : public ewol::Object {
        private:
            ewol::widget::ButtonShared m_button;
            esignal::Connection m_connect;
        protected:
            virtual ~MyObj() { }
            DECLARE_FACTORY(MyObj);
        private:
            void onCallbackUp() {
                APPL_INFO("button pressed: UP");
            }
            void onCallbackDown() {
                APPL_INFO("button pressed: DOWN");
            }
            void onCallbackValue(const bool& _value) {
                APPL_INFO("button value: " << _value);
                if (_value == true) {
                    // We connect signals here: (removable connection)
                    m_connect = m_button->signalDown.connect(this, &appl::MyObj::onCallbackDown);
                } else {
                    // we disconnect the previous connection
                    m_connect.disconnect();
                }
            }
    }
}

Note:

The connection with SharedPtr are static. they keep in internal a WeakPtr to remove connection if the object is removed.

Note:

The connection that return a esignal::Connection are volatil, if you don't keep the connection handle, the connection is automaticly removed.

Declare Signal:

source

#include <ewol/object/Object.hpp>
#include <ewol/widget/Button.hpp>
namespace appl {
    class MyObj : public ewol::Object {
        public:
            ewol::object::Signal<> signalEmpty;
            ewol::object::Signal<bool> signalBoolean;
            ewol::object::Signal<std::string> signalString;
        protected:
            MyObj() :
              signalEmpty(this, "empty"),
              signalBoolean(this, "boolean"),
              signalString(this, "string") {
                // nothing to do..
            }
        public:
            virtual ~MyObj() { }
            DECLARE_FACTORY(MyObj);
        private:
            void process() {
                signalEmpty.emit();
                signalBoolean.emit(false);
                signalString.emit("plop... plop");
            }
    }
}

Conclusion:

You will now able to reise signals between objects...

For more information see e-signal