根据类型切换行为的最佳方式 [英] Best way to switch behavior based on type

问题描述

可能重复:
C# - 有没有更好的替代开启类型"?

考虑经典:

class Widget { }
class RedWidget : Widget { }
class BlueWidget : Widget { }

在大多数情况下，在我的 UI 中，我可以将所有 Widget 视为相同.但是，有一些细微的差异，我需要通过 if 或 switch.

For the most part, in my UI, I can treat all Widgets the same. However, there are minor differences, which I need to if or switch through.

可能的方法:

枚举指标 - 由构造函数设置

enum WidgetVariety { Red, Blue }

class Widget {
    public WidgetVariety Variety { get; protected set; }
}

class RedWidget : Widget {
    public RedWidget() {
        Variety = Red;
    }
}

// Likewise for BlueWidget...

switch (mywidget.Variety) {
case WidgetVariety.Red:
    // Red specific GUI stuff

case WidgetVariety.Blue:
    // Blue specific GUI stuff
}

使用是

Widget w = ...;
if (w is RedWidget) {
    (RedWidget)w ...
}
else if (w is BlueWidget) {
    (BlueWidget)w ...
}

我采用这种方式的原因是 1) 大部分代码已经以这种方式编写，但更难看.2) 90% 的代码是相同的——基本上 GridView 中的一列需要根据类型进行不同的处理.

The reason I've resorted to this is 1) Most of the code is already somewhat written this way, but much uglier. 2) 90% of the code is identical - basically just one column in a GridView needs to be handled differently depending on the type.

你会推荐哪个?(或者任何人有更好的解决方案?)

Which would you recommend? (Or anyone have a better solution?)

编辑我知道我可能会被推荐到访问者模式，但在这种情况下，对于稀疏的、微小的差异来说，这似乎很复杂.

Edit I know I'll probably be recommended to the Visitor Pattern, but that simply seems to complicated for sparse, minor differences in this case.

编辑 2因此，我很难理清的一个特别区别是这两种类型之间的不同.在一种情况下，它检索 bool 值，并将其分配给网格单元格.在另一种情况下，它获取一个字符串值.

Edit 2 So one particular difference I was having a hard time sorting out is this column that is different between the two types. In one case, it retrieves a bool value, and assigns that to the grid cell. In the other case, it gets a string value.

我想在这种情况下，很明显我可以定义:

I suppose in this case, it should be obvious that I could define:

public object virtual GetColumn4Data();

public override GetColumn4Data() { return m_boolval; }

public override GetColumn4Data() { return m_mystring; }

由于使用了object，我一开始觉得这是不对的.但是，是我在单元格中分配的属性的类型，所以当然这是有道理的！

This felt wrong to me initially, due to the use of object. However, that is the type of the property that I am assigning to in the cell, so of course this makes sense!

今天似乎在办公室太久了……

Too long at the office today it seems...

推荐答案

还有另一种可能.使用虚拟调度:

There's another possibility. Use virtual dispatch:

class Widget
{
    public virtual void GuiStuff() { }
} 
class RedWidget : Widget
{
    public override void GuiStuff()
    {
        //... red-specific GUI stuff
        base.GuiStuff();
    }
} 
class BlueWidget : Widget
{
    public override void GuiStuff()
    {
        //... blue-specific GUI stuff
        base.GuiStuff();
    }
} 

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