用非默认构造函数初始化成员类 [英] Initializing member class with non-default constructor

问题描述

我正在尝试创建一个具有SimpleWindow类的gui，该类包含一个textPanel类:

I'm trying to make a gui which has a SimpleWindow class that contains a textPanel class:

class textPanel{
    private:
        std::string text_m;

    public:
        textPanel(std::string str):text_m(str){}
        ~textPanel();
};


class SimpleWindow{
    public:
        SimpleWindow();
        ~SimpleWindow();
        textPanel text_panel_m;
};

SimpleWindow::SimpleWindow():
        text_panel_m(std::string temp("default value"))
{
}

我希望能够使用将转换为std :: string的const char *初始化text_panel_m，而无需制作另一个采用const char *的构造函数.无论如何，我是否应该只使用const char *作为参数创建另一个构造函数?如果我这样做的话，有没有一种方法可以减少使用c ++ 0x的冗余构造函数代码的数量?

I want to be able to initialize the text_panel_m using a const char* that gets converted to a std::string without needing to make another constructor that takes a const char*. Should I just create another constructor with const char* as an argument anyway? If I do it this way is there a way to reduce the amount of redundant constructor code using c++0x?

使用上述方法时，我很难初始化text_panel_m成员变量.g ++给我以下错误:

With the approach above I'm having difficulties initializing the text_panel_m member variable. g++ gives me the following error:

simpleWindow.cpp:49: error: expected primary-expression before ‘temp’
simpleWindow.cpp: In member function ‘bool SimpleWindow::drawText(std::string)’:

如何在不使用默认构造函数的情况下初始化text_panel_m成员变量?

How do I go about initializing the text_panel_m member variable without using the default constructor?

推荐答案

您希望在初始化列表中使用未命名的临时值.一个简单的更改就可以做到:

You want an unnamed temporary value in the initializer list. One simple change will do it:

SimpleWindow::SimpleWindow():
         text_panel_m(std::string("default value"))

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