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问题描述

在下面的代码中,我想将lambda函数连接到QProcess ::错误信号:

In following code I want to connect lambda function to QProcess::error signal:

void Updater::start() {
    QProcess process;
    QObject::connect(&process, &QProcess::error, [=] (QProcess::ProcessError error) {
        qWarning() << "error " << error;
    });
    process.start("MyProgram");
    process.waitForFinished();
}

但我遇到奇怪的错误:

我在这里做错了什么?该代码执行从QObject派生的类的内部方法。该项目配置为可与c ++ 11一起使用。

What I do wrong here? The code executes inside method of class derived from QObject. The project configured to work with c++11.

我在Linux x32上使用Qt 5.3.1和gcc 4.9.2

I use Qt 5.3.1 on Linux x32 with gcc 4.9.2

推荐答案

问题是 QProcess 还有另一个方法,因此编译器只是不知道使用哪种方法。如果要处理重载方法,则应使用下一个:

Problem is that the QProcess has another error() method, so compiler just doesn't know which method use. If you want to deal with overloaded methods, you should use next:

QProcess process;
connect(&process, static_cast<void (QProcess::*)(QProcess::ProcessError)>
(&QProcess::error), [=](QProcess::ProcessError pError) {
    qWarning() << "error " << pError;
});
process.start("MyProgram");
process.waitForFinished();

是的,看起来很丑,但是没有别的办法(只有旧语法?)。

Yes, it looks ugly, but there is no another way (only old syntax?).

此特殊行告诉编译器您要使用 void QProcess :: error(QProcess :: ProcessError error),所以现在没有任何歧义

This special line tells compiler that you want to use void QProcess::error(QProcess::ProcessError error), so now there is no any ambiguity

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07-29 23:33
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