可以锁定变量以防止在c ++中更改它吗？ [英] Can a variable be locked to prevent changes to it in c++?

问题描述

我使用一个成员变量，在程序的某一点我想改变它，但我更喜欢锁定其他地方，以防止意外的更改。

I am using a member variable and at some point of the program I want to change it, but i prefer to "lock it" everywhere else to prevent unintended changes.

代码解释：

class myClass {
    int x;  // This should be prevented to being changed most of the time
    int y;  // Regular variable
    myclass() {x = 1;}
    void foo1 () {x++; y++;} // This can change x
    void foo2 () {x--; y--;} // This shouldn't be able to change x
                             // I want it to throw a compile error
};

问题是：它能以某种方式实现吗？比如永久const_cast？

The question is: Can it be achieved in some way? Something like permanent const_cast?

我知道我可以立即使用构造函数初始化列表和常量，但我需要稍后更改我的变量。

I know I could use constructor initialization list and constant right away, but i need to change my variable later.

推荐答案

好吧，我不喜欢的所有其他答案，所以这里是我的想法：隐藏变量。

Alright, all the other answers I dislike, so here's my idea: hide the variable.

#define READONLY(TYPE, VAR) const TYPE& VAR = this->VAR //C++03
#define READONLY(VARIABLE) const auto& VARIABLE = this->VARIABLE //C++11

class myClass {
    int x;  // This should be prevented to being changed most of the time
    int y;  // Regular variable
    myClass() :x(1), y(2) {}
    void foo1 () {// This can change x
        x++; 
        y++;
    } 
    void foo2 () {// This shouldn't be able to change x
        READONLY(x); //in this function, x is read-only
        x++; //error: increment of read-only variable 'x'
        y++;
    } 
};

还有方法绕过变量的锁定（例如 this - > x ），但对于这些情况无法执行。

There are still ways to bypass the locking of the variable (such as this->x), but nothing can be done for those situations.

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