如何调试失败的信号/插槽连接？ [英] How to debug a failing signal/slot connection?

问题描述

我正在遵循茉莉花布兰切斯书第2章的书籍

I am following the Chapter 2 of Jasmin Blanchettes book

C++-GUI-Programming-with-Qt-4-1st-ed.pdf

尝试使用Qt的MS VS 2008设置对话框GoToCellDialog。

trying to setup the dialog GoToCellDialog using MS VS 2008 with Qt.

该示例编译，对话框显示，但无法在文本更改时输入处理程序方法on_lineEdit_textChanged（）。
为了证明这一点，我将这行添加到插槽方法中：

The example compiles, the dialog appears, but it fails to enter the handler method on_lineEdit_textChanged() on text changes. To prove it, i added this line to the slot method:

label->setText(tr("Changed :"));

强制在标签上进行视觉上的更改。

to force a visual change in the label.

在.ui文件中，元素

<connections/>

为空。我不知道为什么。

is empty. I don't know why.

我决定将此行添加到构造函数中：

I decided to add this line to the constructor:

connect(lineEdit, SIGNAL(textChanged(const QString &)),
this, SLOT(on_lineEdit_textChanged()));

但它不会改变任何东西。

But it doesn't change anything.

我使用IDE生成代码，但首先它生成小写的gotocelldialog。
现在每个名字都是camelCase，代码编译。但是也许我错过了一些东西。

I used the IDE to generate the code, but first it generated gotocelldialog in lowercase. Now every name is camelCase and the code compiles. But perhaps I missed something.

推荐答案

我的程序中使用了一个功能来确保连接已经建立起来： p>

There is a function I use in my program to make sure connections are well established :

 inline void CHECKED_CONNECT( const QObject * sender, const char * signal,
             const QObject * receiver,  const char * method,
             Qt::ConnectionType type = Qt::AutoConnection )
{
  if(!QObject::connect(sender, signal, receiver, method, type))
   qt_assert_x(Q_FUNC_INFO, "CHECKED_CONNECT failed", __FILE__, __LINE__);
}

这是一个常规连接的包装器，它会引发断言错误，并停止程序一旦连接失败。那么它只对您使用源代码进行连接才有用。

This is a wrapper on the usual connect which throws an assertion error and halts the program as soon as a connection fails. Well it will be useful only for the connections you make using the source code.

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