Qt4 QSettings保存枚举值(例如Qt :: CheckState)

问题描述

我想在QSetting中保存QCheckBok的状态，我可以将其值强制转换为int，但也许存在更简单，更合适的方法吗?

i wanna save state of QCheckBok in QSetting, i can cast its value to int but maybe exists more simple and proper method to do it?

这是我的代码:

QSetting setting;
Qt::CheckState checkState;
//...
checkState = (Qt::CheckState)setting.value("checkState", Qt::Unchecked).toUInt();
//...
setting.setValue("checkState", (uint)checkState);
setting.sync();

推荐答案

首先，尝试避免使用C样式强制转换.例如，替换以下行:

Firstly, try to avoid C-style casts. For example, replace the following line:

checkState = (Qt::CheckState)setting.value("checkState", Qt::Unchecked).toUInt();

与此:

checkState = static_cast<Qt::CheckState>(setting.value("checkState", Qt::Unchecked).toUint());

将checkState转换为uint的行也应更改.

The line where you cast checkState to a uint should also be changed.

第二，QSettings依赖QVariant来设置和检索值.通常可以使用Q_DECLARE_METATYPE宏将QVariant扩展为支持其他类型.这是文档:

Secondly, QSettings relies on QVariant for setting and retrieving values. QVariant can usually be expanded to support additional types using the Q_DECLARE_METATYPE macro. Here's the documentation:

http://doc.trolltech.com/4.6/qmetatype.html#Q_DECLARE_METATYPE

但是，此机制似乎不适用于枚举(当您在QVariant上调用value()成员函数时).因此，您现在所拥有的(减去C样式的强制转换)就可以了.

However, this mechanism does not appear to work properly with enumerations (when you call the value() member function on QVariant). So what you have right now (minus the C-style casting) is fine.

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