是否可以将“这个”设置为在匿名函数中？

发布于 2024-09-30 16:54:59 字数 412 浏览 3 评论 0原文

我有一个函数，

public SharpQuery Each(Action<int, HtmlNode> function)
{
    for (int i = 0; i < _context.Count; ++i)
        function(i, _context[i]);
    return this;
}

它为上下文的每个元素调用传入的函数。是否可以在 Action中设置“this”所指的内容？函数？

例如，

sharpQuery.Each((i, node) => /* `this` refers to an HtmlNode here */);

原文

I've got a function,

public SharpQuery Each(Action<int, HtmlNode> function)
{
    for (int i = 0; i < _context.Count; ++i)
        function(i, _context[i]);
    return this;
}

Which calls the passed in function for each element of the context. Is it possible to set what "this" refers to inside Action<int, HtmlNode> function?

For example,

sharpQuery.Each((i, node) => /* `this` refers to an HtmlNode here */);

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初吻给了烟 2024-10-07 16:54:59

稍微改变一下功能，就可以达到想要的效果。

public SharpQuery Each(Action<MyObject, int, HtmlNode> function)
{
    for (int i = 0; i < _context.Count; ++i)
        function(this, i, _context[i]);
    return this;
}

然后您可以像这样编写函数调用：

sharpQuery.Each((self, i, node) => /* do something with `self` which is "this" */);

注意：但是，匿名函数只能访问公共成员。如果匿名函数是在类中定义的，则它将像往常一样访问受保护的成员和私有成员。

例如，

class MyObject
{
    public MyObject(int i)
    {
        this.Number = i;
    }

    public int Number { get; private set; }
    private int NumberPlus { get { return Number + 1; } }

    public void DoAction(Action<MyObject> action)
    {
        action(this);
    }

    public void PrintNumberPlus()
    {
        DoAction(self => Console.WriteLine(self.NumberPlus));  // has access to private `NumberPlus`
    }
}

MyObject obj = new MyObject(20);
obj.DoAction(self => Console.WriteLine(self.Number));     // ok
obj.PrintNumberPlus();                                    // ok
obj.DoAction(self => Console.WriteLine(self.NumberPlus)); // error

With a slight change in the function, you can achieve the desired effect.

public SharpQuery Each(Action<MyObject, int, HtmlNode> function)
{
    for (int i = 0; i < _context.Count; ++i)
        function(this, i, _context[i]);
    return this;
}

Then you could write your function call like so:

sharpQuery.Each((self, i, node) => /* do something with `self` which is "this" */);

Note: The anonymous function will only have access to public members however. If the anonymous function was defined within the class, it will have access to protected and private members as usual.

e.g.,

class MyObject
{
    public MyObject(int i)
    {
        this.Number = i;
    }

    public int Number { get; private set; }
    private int NumberPlus { get { return Number + 1; } }

    public void DoAction(Action<MyObject> action)
    {
        action(this);
    }

    public void PrintNumberPlus()
    {
        DoAction(self => Console.WriteLine(self.NumberPlus));  // has access to private `NumberPlus`
    }
}

MyObject obj = new MyObject(20);
obj.DoAction(self => Console.WriteLine(self.Number));     // ok
obj.PrintNumberPlus();                                    // ok
obj.DoAction(self => Console.WriteLine(self.NumberPlus)); // error

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