[英]Qt Command Pattern QHash/QMap
I've recently implemented a command design pattern in Java with the use of: 我最近使用以下命令在Java中实现了命令设计模式:
private HashMap<Component, CommandInterface> commands;
Where Component
is any Java Component ( JButton
, JMenuItem
, ...) and CommandInterface
is an interface for my Command-Classes. 其中Component
是任何Java组件( JButton
, JMenuItem
,...),而CommandInterface
是我的Command-Classes的接口。
So my question is: How can I accomplish this with C++/Qt ? 所以我的问题是:如何使用C ++ / Qt完成此操作?
I've already used QMap
and QHash
, but both of them need an overloaded operator ( operator<
or operator==
) for their Key
-values. 我已经使用QMap
和QHash
,但他们都需要一个重载运营商( operator<
或operator==
),为他们的Key
-值。
Is the only possible way to derive from QObject
and overload operator<
? 是从QObject
和重载operator<
得出的唯一可能方法吗?
Thanks in advance. 提前致谢。
One very important difference between Java and C++ is that C++ makes a distinction between an object pointer (reference in Java) QObject* o;
Java和C ++之间的一个非常重要的区别是C ++区分了对象指针(Java中的引用) QObject* o;
and an object value QObject o;
和对象值QObject o;
That being said, Qt strongly encourages to create the QObject on the heap (using new). 话虽这么说,Qt强烈鼓励在堆上创建QObject(使用new)。 So you end up with QObject pointers QObject*
. 因此,您最终得到了QObject指针QObject*
。 Then your hashmap will work because comparing the pointers is like comparing integers. 然后您的哈希图将起作用,因为比较指针就像比较整数一样。
QHash<QObject*, CommandInterface*> commands;
Do not forget to manage the lifetime of your objects though, you do not have a garbage collector like in Java. 但是,不要忘记管理对象的生命周期,因为您没有像Java那样的垃圾收集器。 You can use the Qt tree ownership for convenience, depending on your needs : http://doc.qt.io/qt-5/objecttrees.html 您可以根据需要使用Qt树所有权以方便使用: http : //doc.qt.io/qt-5/objecttrees.html
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