Qt 信号和槽的参数类型，const 引用限定符重要吗? [英] Argument type for Qt signal and slot, does const reference qualifiers matters?

问题描述

对于以下类型的信号和槽

For signal and slot of below type

signals:
    void textChanged(const QString &);

public slots:
    void setText(const QString & text)

textChanged 和 setText 的参数类型似乎适用于 const 和 &.与仅使用 QString 相比，常量和引用限定是否有任何区别?

the type of argument of textChanged and setText seems to work invarable of const and &. Does the constant and reference qualification make any difference compared to just using QString ?

QObject::connect(a,SIGNAL(textChanged(QString)),b,SLOT(setText(QString)));
QObject::connect(a,SIGNAL(textChanged(const QString &)),b,SLOT(setText(const QString &)));

当信号或插槽中使用不兼容的类型时，我没有注意到输出窗口显示错误消息.我认为信号槽机制能够在编译时检测参数类型错误.

I did not notice the output window showing error messages when there is incompatible type being used in SIGNAL or SLOT. I thought the signal slot mechanism is capable of detecting argument type error at compile time.

推荐答案

Qt 检查 规范化签名，意思是

标准化将空白减少到最小值，将const"移到前面在适当的情况下，删除const"从值类型并替换 const有值的引用.

Normalization reduces whitespace to a minimum, moves 'const' to the front where appropriate, removes 'const' from value types and replaces const references with values.

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