C#之动态语言扩展

DLR

在.NET Framework中，DLR2位于System.Dynamic命名空间和System.Runtime.CompilerServices命名空间的几个类中。

dynamic 类型

可以发现staticPerson出现了编译错误，而dynamicPerson并没有，因为定义为dynamic的对象可以在运行期改变其类型，甚至改变多次，这与强制转换类型是不一样的，它在编译期不会做检查。

对于dynamic 类型有两个限制:动态对象不支持扩展方法，匿名函数（lambda表达式）也不能用于动态方法调用参数，因此LINQ不能用于动态对象。大多数LINQ调用都是扩展方法，而lambda表达式用作这些扩展方法的参数。

包含DLR ScriptRuntime

项目通过NuGet安装IronPython，然后using Microsoft.Scripting.Hosting,就有了ScriptRuntime，

就可以执行存储在文件中的代码段或完整的脚本。

例：

xaml文件

<Window x:Class="DiscountWPF.MainWindow"

        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

        xmlns:local="clr-namespace:DiscountWPF"

        mc:Ignorable="d"

        Title="MainWindow" Height="450" Width="300">

    <Grid AutomationProperties.HelpText="disc based on cost">

        <Grid.RowDefinitions>

            <RowDefinition/>

            <RowDefinition/>

            <RowDefinition/>

            <RowDefinition/>

            <RowDefinition/>

            <RowDefinition/>

            <RowDefinition/>

            <RowDefinition/>

        </Grid.RowDefinitions>

        <RadioButton x:Name="CostRadioButton" Grid.Row="0" VerticalAlignment="Center" >Disc Based on Cost</RadioButton>

        <RadioButton x:Name="NumRadioButton" Grid.Row="1" VerticalAlignment="Center" >Disc Based on No of Items</RadioButton>

        <StackPanel Grid.Row="2" Orientation="Horizontal" VerticalAlignment="Center">

            <TextBlock>Total No of Items:</TextBlock>

            <TextBox x:Name="totalItems" Width="180" HorizontalContentAlignment="Right"/>

        </StackPanel>

        <StackPanel Grid.Row="3" Orientation="Horizontal" VerticalAlignment="Center">

            <TextBlock>Total Amount</TextBlock>

            <TextBox x:Name="totalAmount" Width="178" HorizontalAlignment="Left" VerticalAlignment="Center" HorizontalContentAlignment="Right"/>

        </StackPanel>

        <StackPanel Grid.Row="7" Orientation="Vertical" VerticalAlignment="Center">

            <Button x:Name="calDisc" Content="Calc Discount" Width="100" Click="calDisc_Click"/>

            <Button x:Name="calTax" Content="Cal  Tax" Width="100" Margin="0,10,0,0" Click="calTax_Click"/>

        </StackPanel>

        <StackPanel Grid.Row="4" Orientation="Horizontal" VerticalAlignment="Center">

            <TextBlock>Discounted Amount:</TextBlock>

            <TextBlock x:Name="label"></TextBlock>

        </StackPanel>

        <StackPanel Grid.Row="5" Orientation="Horizontal" VerticalAlignment="Center">

            <TextBlock>Amount with Tax:</TextBlock>

            <TextBlock x:Name="labelA"></TextBlock>

        </StackPanel>

    </Grid>

</Window>

using Microsoft.Scripting.Hosting;

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Data;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Imaging;

using System.Windows.Navigation;

using System.Windows.Shapes;

namespace DiscountWPF

{

    /// <summary>

    /// MainWindow.xaml 的交互逻辑

    /// </summary>

    public partial class MainWindow : Window

    {

        public MainWindow()

        {

            InitializeComponent();

        }

        private void calDisc_Click(object sender, RoutedEventArgs e)

        {

            string scriptToUse;

            if (CostRadioButton.IsChecked.Value)

            {

                scriptToUse = "AmountDisc.py";

            }

            else

            {

                scriptToUse = "CountDisc.py";

            }

            ScriptRuntime scriptRuntime = ScriptRuntime.CreateFromConfiguration();

            ScriptEngine pythEng = scriptRuntime.GetEngine("python");

            ScriptSource source = pythEng.CreateScriptSourceFromFile(scriptToUse);

            ScriptScope scope = pythEng.CreateScope();

            scope.SetVariable("prodCount", Convert.ToInt32(totalItems.Text));

            scope.SetVariable("amt", Convert.ToDecimal(totalAmount.Text));

            source.Execute(scope);

            label.Text = scope.GetVariable("retAmt").ToString();

        }

        private void calTax_Click(object sender, RoutedEventArgs e)

        {

            ScriptRuntime scriptRuntime = ScriptRuntime.CreateFromConfiguration();

            dynamic calcRatet = scriptRuntime.UseFile("CalcTax.py");

            labelA.Text = calcRatet.CalcTax(Convert.ToDecimal(label.Text)).ToString();

        }

    }

}

从代码可知，ScriptRuntime对象是通过配置文件来产生的，因为调用了ScriptRuntime.CreateFromConfiguration()方法产生的，因此，本项目的App.config如下：

<?xml version="1.0" encoding="utf-8" ?>

<configuration>

	<configSections>

		<section name="microsoft.scripting" type="Microsoft.Scripting.Hosting.Configuration.Section, Microsoft.Scripting"/>

	</configSections>

	<microsoft.scripting>

		<languages>

			<language names="IronPython;Python;py" extensions=".py" displayName="Python" type="IronPython.Runtime.PythonContext, IronPython"/>

		</languages>

	</microsoft.scripting>

	<startup>

		<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.8" />

	</startup>

</configuration>

Calc Discount按钮的click事件调用的方法是通过依次创建ScriptRuntime，ScriptEngine，ScriptSource,ScriptScope对象,对ScriptSource进行执行，从ScriptScope设定变量的值，获取变量的值。

Cal Tax按钮的click事件调用的方法是创建ScriptRuntime，然后通过该对象的UseFile方法，得到Dynamic类型对象，然后通过该动态对象，调用脚本中的方法。

CountDisc.py

discCount=5

discAmt=0.1

retAmt=amt

if(prodCount>discCount):

    retAmt=amt-(amt*discAmt)

AmountDisc.py

discAmt=0.25

retAmt=amt

if amt>25:

    retAmt=amt-(amt*discAmt)

CalTax.py

def CalcTax(amount):

    return amount*1.075

DynamicObject和ExpandoObject

DynamicObject

创建自己的动态对象，要么从DynamicObject中派生，也要么使用ExpandoObject

using System;

using System.Collections.Generic;

using System.Dynamic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace DynamicDemo

{

    class Program

    {

        static void Main(string[] args)

        {

            dynamic wroxDyn = new WroxDynamicObject();

            wroxDyn.FirstName = "John";

            wroxDyn.LastName = "Yang";

            Console.WriteLine(wroxDyn.GetType());

            Console.WriteLine("{0}--{1}", wroxDyn.FirstName, wroxDyn.LastName);

            Func<DateTime, string> GetTomo = today => today.AddDays(1).ToShortDateString();

            wroxDyn.GetTomorrow = GetTomo;

            Console.WriteLine("Tomorrow is {0}", wroxDyn.GetTomorrow(DateTime.Now));

        }

    }

    class WroxDynamicObject : DynamicObject

    {

        Dictionary<string, object> _dynamicData = new Dictionary<string, object>();

        public override bool TryGetMember(GetMemberBinder binder, out object result)

        {

            bool success = false;

            result = null;

            if (_dynamicData.ContainsKey(binder.Name))

            {

                result = _dynamicData[binder.Name];

                success = true;

            }

            else

            {

                result = "Property not found";

            }

            return success;

        }

        public override bool TrySetMember(SetMemberBinder binder, object value)

        {

            _dynamicData[binder.Name] = value;

            return true;

        }

        public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result)

        {

            dynamic method = _dynamicData[binder.Name];

            result = method((DateTime)args[0]);

            return result != null;

        }

    }

}

output

DynamicDemo.WroxDynamicObject

John--Yang

Tomorrow is 2022/2/5

ExpandoObject

ExpandoObject不用重写方法，可以直接使用，如果需要控制动态对象中属性的添加和访问，则使用DynamicObject是最佳选择，其他情况，则使用dynamic或者ExpandoObject。

using System;

using System.Collections.Generic;

using System.Dynamic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace DynamicDemo

{

    class Program

    {

        static void Main(string[] args)

        {

            dynamic wroxDyn = new ExpandoObject();

            wroxDyn.FirstName = "John";

            wroxDyn.LastName = "Yang";

            Console.WriteLine(wroxDyn.GetType());

            Console.WriteLine("{0}--{1}", wroxDyn.FirstName, wroxDyn.LastName);

            Func<DateTime, string> GetTomo = today => today.AddDays(1).ToShortDateString();

            wroxDyn.GetTomorrow = GetTomo;

            Console.WriteLine("Tomorrow is {0}", wroxDyn.GetTomorrow(DateTime.Now));

        }

    }

}

output

System.Dynamic.ExpandoObject

John--Yang

Tomorrow is 2022/2/5

利用ExpandoObject，来储存任意数据类型的数据的一个Demo:

using System;

using System.Collections.Generic;

using System.Dynamic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace DynamicDemo

{

    class Program

    {

        static void Main(string[] args)

        {

            var retList = new List<dynamic>();

            dynamic expObj=new ExpandoObject();

            ((IDictionary<string, object>)expObj).Add("john", 10);

            retList.Add(expObj);

            dynamic expObj1 = new ExpandoObject();

            ((IDictionary<string, object>)expObj1).Add("yang", DateTime.Now);

            retList.Add(expObj1);

            foreach(var dy in retList)

            {

                var tempDic = (IDictionary<string, object>)dy;

                foreach(var kv in tempDic)

                {

                    Console.WriteLine(kv.Key);

                    Console.WriteLine(kv.Value);

                }

            }

        }

    }

}

output

john

10

yang

2022/2/4 23:35:21