我可以有复制构造函数的QObject的子类吗? [英] Could I have copy constructor for subclass of QObject?
问题描述
这里我们可以看到,没有复制结构和复制赋值运算符可评价。但是此处我们可以阅读 qRegisterMetaType
和 Q_DECLARE_METATYPE
必须具有公共默认构造函数,公共副本构造函数和公共析构函数。问题是:谁在说谎?
Here we can read that no copy construct and copy assignment operator evaluable. But here we can read that qRegisterMetaType
and Q_DECLARE_METATYPE
have to have public default constructor, public copy constructor and public destructor. The question is: who is telling a lie? Or I did not understand it correctly?
推荐答案
一切都是真的:
1. QObject
无法复制,其所有后代也无法复制。
2. Q_DECLARE_METATYPE
接受对象与公共构造函数,复制构造函数和析构函数。
Everything is true:
1. QObject
can't be copied and all its descendants can't be copied also.
2. Q_DECLARE_METATYPE
accepts objects with public constructor, copy constructor and destructor.
没有矛盾,因为你不能注册 QObject
Q_DECLARE_METATYPE
的后代。
There is no contradiction, because you can't register QObject
descendants with Q_DECLARE_METATYPE
.
编辑:
您将类转换为 QVariant
,它使用复制构造函数来创建对象的副本:
When you convert your class to QVariant
it uses a copy constructor to make a copy of your object:
void *ptr = QMetaType::construct(x->type, copy);
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