EWOL: Object model

Table of Contents

• Objectifs:
• Basis of the ewol::Object
• Create an Object:
• Remove an Object:
• Retrieve an Object:

Objectifs:

• Understand ewol basic ewol::Object
• Use ewol::Object correctly

Basis of the ewol::Object

An object in Ewol is a simple class: ewol::Object This object is the basis of all element in the ewol system. This is designed to manage many common things:

• Unique ID
• Name
• Parameters
• Signal generation
• Xml configuration
• Removing

Note:

Please do not compare with the gObject basic class...

Create an Object:

Creating an object is really simple:

ewol::widget::ButtonShared tmpButon = ewol::widget::Button::create();
APPL_INFO("We just create a button widget with unique ID=" << tmpButon->getId() << " name='" << tmpButon->propertyName.get() << "'");

Note that all object created are ememory::SharedPtr base for the current version on std::shared_ptr. We wrapped it because the current inplementation of std::shared_ptr is not thread safe, and we want use a thread-safe version of it.

Note:

The widget is not stored in a ememory::SharedPtr<ewol::widget::Button> but in a ewol::widget::ButtonShared to simplify the using of the pointer.
You have also: ememory::WeakPtr<ewol::widget::Button> = ewol::widget::ButtonWeak

Set the name of the object:

tmpButon->propertyName.set("my widget name");
APPL_INFO("We just create an Object with ID=" << tmpButon->getId() << " name='" << tmpButon->propertyName.get() << "'");

Remove an Object:

Simply use the function:

tmpButon->destroy();

This function request his parrent to remove the ememory::SharedPtr it keep on it. And when all ememory::SharedPtr is removed the object will be really removed.

At his point we can think an object is alive all the time someone keep a reference on it, then when you are not a parrent of the object, do not keep a ememory::SharedPtr but a ememory::WeakPtr.

Note:

If some Object is not removed when you close the application, the system inform you with displaying all object alive.

Retrieve an Object:

In Ewol this is possible to get a object with his name.

Find a global Object (ouside an Object)

#include <ewol/context/Context.hpp>

ewol::ObjectShared tmpObject = ewol::getContext().getEObjectManager().getObjectNamed("obj Name");
if (tmpObject == nullptr) {
    APPL_ERROR("The Object does not exist");
}

Find a global Object (inside an Object)

ewol::ObjectShared tmpObject = getObjectNamed("obj Name");
if (tmpObject == nullptr) {
    APPL_ERROR("The Object does not exist");
}

Find a sub-object

ewol::ObjectShared tmpObject = getSubObjectNamed("obj Name");
if (tmpObject == NULL) {
    APPL_ERROR("The Object does not exist");
}

retriving your object type

It could be really interesting to retrive your own instance:

ewol::ObjectShared tmpObject ...;

appl::MyOwnObjectShared myObject = std::dynamic_pointer_cast<appl::MyOwnObject>(tmpObject);