Self-Deleting Objects with Inheritance

[Paul McKenzie]

A very common example usage of my class would be a button that brings up the Settings form. i.e:

void btn_Settings(Object *sender, EventArgs *e)
{
	FormSetup fs(L"Settings", 600, 400);
	fs.Events.Create = fSettings_Create;

	Form *fSettings = new Form(fs);
	
	// After the next line Show() this function finishes and the shared_ptr goes out of scope which deletes my object.
	// As soon as I move the mouse over the Settings window my program crashes because of an Access Violation when Windows tries calling Form::WndProc.

	// std::shared_ptr<Form> fSettings(new Form(fs));	// Deletes Form too soon!

	fSettings->Show();
};

Of course it will delete it too soon. This has nothing to do with shared_ptr, but with C++. You create a local variable, so what happens to local variables when a function returns?

You need to have a high-level design that properly implements your idea of how long of a lifetime each one of your objects will have. If you declare a local variable, then its lifetime is local to that scope. If you declare a class member, its lifetime is determined by the lifetime of the object, etc.

Regards,

Paul McKenzie