QFutureWatcher不调用连接插槽 [英] QFutureWatcher not calling connected slot

问题描述

我有以下代码实现 QtConcurrent :: run（）与 QFutureWatcher 启动 fetch（）函数运行一个shell进程。完成后，我想调用 writeDesc 函数，但它从不调用。

I have the following code which implements QtConcurrent::run() with QFutureWatcher to start the fetch() function which runs a shell process. Upon completion, I want to call the writeDesc function, but it never gets called.

void MyClass::on_fetchButton_clicked()
{
    QFuture<void> fetcher;
    QFutureWatcher<void> watcher;
    connect(&watcher, SIGNAL(finished()), this, SLOT(writeDesc()));
    fetcher = QtConcurrent::run(this, &MyClass::fetch);
    watcher.setFuture(fetcher);
}

void MyClass::fetch()
{
    [...]
    qDebug()<<"Thread done";
}

void MyClass::writeDesc()
{
    qDebug()<<"Slot called";
    [...]
}

fetch （）工作正常，但程序只显示调试消息线程完成，而不是 Slot调用。为什么 writeDesc 被调用？

fetch() works fine but the program shows only the debug message Thread done and not Slot called. Why isn't writeDesc being called?

推荐答案

问题是，当离开 MyClass :: on_fetchButton_clicked（）方法时，watcher对象被销毁。被销毁的对象不能发出东西。尝试在类的构造函数中分配和连接观察程序。不要忘记在析构器中销毁。

The problem is that the watcher object is destroyed when leaving the MyClass::on_fetchButton_clicked() method. A destroyed object can not emit something. Try to allocate and connect the watcher in the constructor of your class. Don't forget to destroy in the destructor.

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