如何定义变量lambda函数 [英] How to define variable as lambda function

问题描述

（lambda函数可能会或可能不会有什么我要找的，我不知道）

(Lambda function may or may not be what I'm looking for, I'm not sure)

从本质上讲就是我要完成的是这样的：

Essentially what I'm trying to accomplish is this:

int areaOfRectangle = (int x, int y) => {return x * y;};

但它给了错误：无法将lambda表达式类型'诠释'，因为它不是委托键入

but it gives error: "Cannot convert lambda expression to type 'int' because it is not a delegate type"

更详细的问题（这真的无关的问题，但我知道有人会问）是：

The more detailed problem (that really has nothing to do with the question, but I know someone will ask) is:

我有几个功能，从一个覆盖OnLayout和一些更多的功能，每个那些依赖于分支。为了提高可读性，并设置为以后的扩展先例，我想要的功能分支从OnLayout所有类似于。要做到这一点，我需要划分它们和重用命名尽可能的：

I have several functions that branch from an overridden OnLayout and several more functions that each of those depend on. For readability and to set precedent for later expansion, I want the functions that branch from OnLayout to all look similar. To do that, I need to compartmentalize them and reuse naming as much as possible:

protected override void OnLayout(LayoutEventArgs levent)
    switch (LayoutShape)
    {
        case (square):
            doSquareLayout();
            break;
        case (round):
            doRoundLayout();
            break;
        etc..
        etc..
    }
void doSquareLayout()
{
    Region layerShape = (int Layer) =>
    {
        //do some calculation
        return new Region(Math.Ceiling(Math.Sqrt(ItemCount)));
    }
    int gradientAngle = (int itemIndex) =>
    {
        //do some calculation
        return ret;
    }
    //Common-ish layout code that uses layerShape and gradientAngle goes here
}
void doRoundLayout()
{
    Region layerShape = (int Layer) =>
    {
        //Do some calculation
        GraphicsPath shape = new GraphicsPath();
        shape.AddEllipse(0, 0, Width, Height);
        return new Region(shape);
    }
    int gradientAngle = (int itemIndex) =>
    {
        //do some calculation
        return ret;
    }
    //Common-ish layout code that uses layerShape and gradientAngle goes here
}

所有我现在找到的例子说，你必须声明一个委托，但我的知道的我见过一个班轮拉姆达声明...

All the examples I find right now say you have to declare a delegate but I know I've seen a one liner lambda declaration...

推荐答案

尝试 Func键< INT，INT，INT> areaOfRectangle =（INT X，int y）对= GT; {返回X * Y;}; 而不是

函数功能的工作原理为代表

的看看这里的LAMDA表达式的用法更多信息

的这个答案也是相关的，具有

如果你正在做它的可读性和将要再现相同功能 layerShape 和 gradientAngle ，您可能希望为这些功能明确的代表，以表明他们其实都是一样的。仅仅是一个想法。

If you're doing it for readability and are going to reproduce the same functions layerShape and gradientAngle, you might want to have explicit delegates for those functions to show they are in fact the same. Just a thought.

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