参数与成员变量

发布于 2024-07-13 13:37:42 字数 1578 浏览 4 评论 0原文

我最近一直在使用别人的代码，我意识到这个人对于私有变量和方法参数的理念与我截然不同。我通常认为私有变量只应该在以下情况下使用：

需要存储变量以供以后调用。
存储在变量中的数据在类中全局使用。
当需要全局操作变量时（这与需要通过每个类方法读取变量截然不同）。
当它将使编程变得更加容易时。（诚然含糊不清，但在很多情况下，人们必须避免将自己陷入困境）。

（我承认，上面的许多内容都略有重复，但它们似乎都不同，足以值得这样对待......）

这似乎是防止意外更改变量的最有效方法。遵循这些标准似乎还允许最终操作外部引用（如果该类最终被修改），从而为您在未来留下更多选择。这只是一个风格问题（就像一个真正的括号或匈牙利命名约定），还是我的这种信念有道理？在这种情况下实际上有最佳实践吗？

编辑
我认为这需要纠正。我在上面使用了“全局”，我实际上的意思是“通过实例方法全局”，而不是“任何地方、任何地方都可以全局访问”。

编辑2
有人要求一个例子：

class foo
{
    private $_my_private_variable;

    public function __constructor__()
    {
    }

    public function useFoo( $variable )
    {
        // This is the line I am wondering about,
        // there does not seem to be a need for storing it.
        $this->_my_private_variable = $variable; 
        $this->_doSometing();
    }

    private function _doSomething()
    {

        /*
          do something with $this->_my_private_variable.
        */
        // This is the only place _my_private_variable is used.
        echo $this->_my_private_variable;
    }
}

这就是我会这样做的方式：

class foo
{

    public function __constructor__()
    {
    }

    public function useFoo( $variable )
    {
        $this->_doSometing( $variable );
    }

    private function _doSomething( $passed_variable )
    {
        /*
          do something with the parameter.
        */
        echo $passed_variable;
    }
}

原文

I've recently been working with someone else's code and I realized that this individual has a very different philosophy regarding private variables and method parameters than I do. I generally feel that private variables should only be used in a case when:

The variable needs to be stored for recall later.
The data stored in the variable is used globally in the class.
When the variable needs to be globally manipulated (something decidedly different from the need to read the variable by every class method).
When it will make programming substantially easier. (Admittedly vague, but one has to be in many circumstances to avoid painting oneself into a corner).

(I admit, that many of the above are slightly repetitive, but they each seem different enough to merit such treatment... )

It just seems that this is the most efficient means of preventing changing a variable by accident. It also seems like following these standards will allow for the eventual manipulation of external references (if the class is eventually modified), thus leaving you with further options in the future. Is this simply a style issue (like one true bracket or Hungarian naming conventions), or do I have justification in this belief? Is there actually a best practice in this case?

edit
I think this needs to be corrected. I used "globally" above where I actually meant, "globally by instance methods" not "globally accessible by anything, anywhere".

edit2
An example was asked for:

class foo
{
    private $_my_private_variable;

    public function __constructor__()
    {
    }

    public function useFoo( $variable )
    {
        // This is the line I am wondering about,
        // there does not seem to be a need for storing it.
        $this->_my_private_variable = $variable; 
        $this->_doSometing();
    }

    private function _doSomething()
    {

        /*
          do something with $this->_my_private_variable.
        */
        // This is the only place _my_private_variable is used.
        echo $this->_my_private_variable;
    }
}

This is the way I would have done it:

class foo
{

    public function __constructor__()
    {
    }

    public function useFoo( $variable )
    {
        $this->_doSometing( $variable );
    }

    private function _doSomething( $passed_variable )
    {
        /*
          do something with the parameter.
        */
        echo $passed_variable;
    }
}

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