用 C# 编写我的第一个 DSL 并沉迷于 func<T> 和 Action

Question

我正在为一个简单的工作工具编写我的第一个 DSL。我正在使用构建器模式来设置复杂的父对象，但在构建父对象的子集合时遇到了砖墙。这是一个示例：

用途：

var myMorningCoffee = Coffee.Make.WithCream().WithOuncesToServe(16);

带闭包的示例（我认为这就是它们的名称）：

var myMorningCoffee = Coffee.Make.WithCream().PourIn( 
                        x => {
                                x.ShotOfExpresso.AtTemperature(100);
                                x.ShotOfExpresso.AtTemperature(100).OfPremiumType();
                             }
                        ).WithOuncesToServe(16);

示例类（没有子 PourIn() 方法，因为这是我想要弄清楚的。）

 public class Coffee
 {
   private bool _cream;

   public Coffee Make { get new Coffee(); }
   public Coffee WithCream()
   {
     _cream = true;
     return this;
   }
   public Coffee WithOuncesToServe(int ounces)
   {
     _ounces = ounces;
     return this;
   }
 }

因此，在我的工作应用程序中，我可以很好地构建复杂的对象，但我一生都无法弄清楚如何为父对象上的子集合获取 lambda 编码。 （在本例中是 expresso 的镜头（子集合））。

也许我在这里混淆了概念，我不介意直截了当；但是，我真的很喜欢它的阅读方式，并想弄清楚如何让它发挥作用。

谢谢， 山姆

Answer 1

如果 .IncludeApps 接受一组 AppRegistrations 会怎样

IncludeApps(params IAppRegistration[] apps)

然后

public static class App
{
  public static IAppRegistration IncludeAppFor(AppType type)
  {
    return new AppRegistration(type);
  }
}

public class AppRegistration
{
  private AppType _type;
  private bool _cost;

  public AppRegistration(AppType type)
  {
    _type = type;
  }

  public AppRegistration AtNoCost()
  { 
    _cost = 0;
    return this;
  }
}

所以最终它会看起来像这样......

.IncludeApps
(
  App.IncludeAppFor(AppType.Any), 
  App.IncludeAppFor(AppType.Any).AtNoCost()
)

在您的 IncludeApps 方法中，您将检查注册并根据需要创建对象。

Answer 2

走代理路线也许这样可行？

var aPhone = MyPhone.Create;
  MyPhone.Create.IncludeApps
  (
    x =>
      {
        x.IncludeAppFor(new object());
      }
  );

class MyPhone
  {
    public MyPhone IncludeApps(Action<MyPhone> includeCommand)
    {
        includeCommand.Invoke(this);
        return this;
    }
  }

如果您没有设置委托路线，参数可能会起作用？

var anotherPhone = MyPhone.Create.IncludeApps(
    new IncludeAppClass(AppType.Math),
    new IncludeAppClass(AppType.Entertainment).AtNoCost());


class MyPhone
{
    internal MyPhone IncludeApps(params IncludeAppClass[] includeThese)
    {
        if (includeThese == null)
        {
            return this;
        }
        foreach (var item in includeThese)
        {
            this.Apps.Add(Item);
        }
        return this;
    }
}

Answer 3

好的，所以我想出了如何使用额外的表达式构建器来编写我的 DSL。这就是我希望我的 DSL 读取的方式：

var myPreferredCoffeeFromStarbucks =
            Coffee.Make.WithCream().PourIn(
                x =>
                    {
                        x.ShotOfExpresso().AtTemperature(100);
                        x.ShotOfExpresso().AtTemperature(100).OfPremiumType();
                    }
                ).ACupSizeInOunces(16);

这是我的及格测试：

[TestFixture]
public class CoffeeTests
{
    [Test]
    public void Can_Create_A_Caramel_Macchiato()
    {
        var myPreferredCoffeeFromStarbucks =
            Coffee.Make.WithCream().PourIn(
                x =>
                    {
                        x.ShotOfExpresso().AtTemperature(100);
                        x.ShotOfExpresso().AtTemperature(100).OfPremiumType();
                    }
                ).ACupSizeInOunces(16);

        Assert.IsTrue(myPreferredCoffeeFromStarbucks.expressoExpressions[0].ExpressoShots.Count == 2);
        Assert.IsTrue(myPreferredCoffeeFromStarbucks.expressoExpressions[0].ExpressoShots.Dequeue().IsOfPremiumType == true);
        Assert.IsTrue(myPreferredCoffeeFromStarbucks.expressoExpressions[0].ExpressoShots.Dequeue().IsOfPremiumType == false);
        Assert.IsTrue(myPreferredCoffeeFromStarbucks.CupSizeInOunces.Equals(16));
    }
}

这是我的 CoffeeExpressionBuilder DSL 类：

public class Coffee
{
    public List<ExpressoExpressionBuilder> expressoExpressions { get; private set; }

    public bool HasCream { get; private set; }
    public int CupSizeInOunces { get; private set; }

    public static Coffee Make
    {
        get
        {
            var coffee = new Coffee
                             {
                                 expressoExpressions = new List<ExpressoExpressionBuilder>()
                             };

            return coffee;
        }
    }

    public Coffee WithCream()
    {
        HasCream = true;
        return this;
    }

    public Coffee ACupSizeInOunces(int ounces)
    {
        CupSizeInOunces = ounces;

        return this;
    }

    public Coffee PourIn(Action<ExpressoExpressionBuilder> action)
    {
        var expression = new ExpressoExpressionBuilder();
        action.Invoke(expression);
        expressoExpressions.Add(expression);

        return this;
    }

    }

public class ExpressoExpressionBuilder
{
    public readonly Queue<ExpressoExpression> ExpressoShots = 
        new Queue<ExpressoExpression>();

    public ExpressoExpressionBuilder ShotOfExpresso()
    {
        var shot = new ExpressoExpression();
        ExpressoShots.Enqueue(shot);

        return this;
    }

    public ExpressoExpressionBuilder AtTemperature(int temp)
    {
        var recentlyAddedShot = ExpressoShots.Peek();
        recentlyAddedShot.Temperature = temp;

        return this;
    }

    public ExpressoExpressionBuilder OfPremiumType()
    {
        var recentlyAddedShot = ExpressoShots.Peek();
        recentlyAddedShot.IsOfPremiumType = true;

        return this;
    }
}

public class ExpressoExpression
{
    public int Temperature { get; set; }
    public bool IsOfPremiumType { get; set; }

    public ExpressoExpression()
    {
        Temperature = 0;
        IsOfPremiumType = false;
    }
}

欢迎提出任何建议。