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
Disc Based on Cost
Disc Based on No of Items
Total No of Items:
Total Amount
Discounted Amount:
Amount with Tax:
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
{
///
/// MainWindow.xaml 的交互逻辑
///
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" ?>
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 GetTomo = today => today.AddDays(1).ToShortDateString();
wroxDyn.GetTomorrow = GetTomo;
Console.WriteLine("Tomorrow is {0}", wroxDyn.GetTomorrow(DateTime.Now));
}
}
class WroxDynamicObject : DynamicObject
{
Dictionary _dynamicData = new Dictionary();
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 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 expObj=new ExpandoObject();
((IDictionary)expObj).Add("john", 10);
retList.Add(expObj);
dynamic expObj1 = new ExpandoObject();
((IDictionary)expObj1).Add("yang", DateTime.Now);
retList.Add(expObj1);
foreach(var dy in retList)
{
var tempDic = (IDictionary)dy;
foreach(var kv in tempDic)
{
Console.WriteLine(kv.Key);
Console.WriteLine(kv.Value);
}
}
}
}
}
output
john
10
yang
2022/2/4 23:35:21