这非常容易做到。我构建了以下方便的包装器。它们的结构使得您可以从定义方法或表达式的源代码片段构建程序集，并使用 DynamicCodeManager 的帮助器方法按名称调用它们。
该代码是根据调用而按需编译的。添加更多方法将导致下次调用时自动重新编译。
您仅提供一个方法体。如果您不想返回值，则返回 null，并且不必费心使用 InvokeMethod 返回的对象。
如果您在商业代码中使用它，请帮我一个忙并相信我的工作。这个库中真正的瑰宝是调用支持。编译代码不是问题，而是调用。当您有可变长度的参数列表时，让反射正确匹配方法签名是相当棘手的。这就是 DynamicBase 存在的原因：编译器解析绑定到这个显式声明的基类的方法，使我们能够访问正确的 VMT。从那时起，一切都会水落石出。
我还应该指出，此功能使您的桌面应用程序容易受到脚本注入攻击。您应该非常小心地审查脚本的来源，或者降低生成的程序集运行时的信任级别。
动态库.cs
using System.Reflection;
namespace Dynamo
{
public abstract class DynamicBase
{
public bool EvaluateCondition(string methodName, params object[] p)
{
methodName = string.Format("__dm_{0}", methodName);
BindingFlags flags = BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.NonPublic;
return (bool)GetType().InvokeMember(methodName, flags, null, this, p);
}
public object InvokeMethod(string methodName, params object[] p)
{
BindingFlags flags = BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.NonPublic;
return GetType().InvokeMember(methodName, flags, null, this, p);
}
public double Transform(string functionName, params object[] p)
{
functionName = string.Format("__dm_{0}", functionName);
BindingFlags flags = BindingFlags.InvokeMethod | BindingFlags.Instance | BindingFlags.NonPublic;
return (double)GetType().InvokeMember(functionName, flags, null, this, p);
}
}
}
动态代码管理器.cs
using System;
using System.CodeDom.Compiler;
using System.Collections.Generic;
using System.Diagnostics;
using System.Reflection;
using System.Text;
using Microsoft.CSharp;
namespace Dynamo
{
public static class DynamicCodeManager
{
#region internal statics and constants
static Dictionary<string, string> _conditionSnippet = new Dictionary<string, string>();
static Dictionary<string, string> _methodSnippet = new Dictionary<string, string>();
static string CodeStart = "using System;\r\nusing System.Collections.Generic;\r\n//using System.Linq;\r\nusing System.Text;\r\nusing System.Data;\r\nusing System.Reflection;\r\nusing System.CodeDom.Compiler;\r\nusing Microsoft.CSharp;\r\nnamespace Dynamo\r\n{\r\n public class Dynamic : DynamicBase\r\n {\r\n";
static string DynamicConditionPrefix = "__dm_";
static string ConditionTemplate = " bool {0}{1}(params object[] p) {{ return {2}; }}\r\n";
static string MethodTemplate = " object {0}(params object[] p) {{\r\n{1}\r\n }}\r\n";
static string CodeEnd = " }\r\n}";
static List<string> _references = new List<string>("System.dll,System.dll,System.Data.dll,System.Xml.dll,mscorlib.dll,System.Windows.Forms.dll".Split(new char[] { ',' }));
static Assembly _assembly = null;
#endregion
public static Assembly Assembly { get { return DynamicCodeManager._assembly; } }
#region manage snippets
public static void Clear()
{
_methodSnippet.Clear();
_conditionSnippet.Clear();
_assembly = null;
}
public static void Clear(string name)
{
if (_conditionSnippet.ContainsKey(name))
{
_assembly = null;
_conditionSnippet.Remove(name);
}
else if (_methodSnippet.ContainsKey(name))
{
_assembly = null;
_methodSnippet.Remove(name);
}
}
public static void AddCondition(string conditionName, string booleanExpression)
{
if (_conditionSnippet.ContainsKey(conditionName))
throw new InvalidOperationException(string.Format("There is already a condition called '{0}'", conditionName));
StringBuilder src = new StringBuilder(CodeStart);
src.AppendFormat(ConditionTemplate, DynamicConditionPrefix, conditionName, booleanExpression);
src.Append(CodeEnd);
Compile(src.ToString()); //if the condition is invalid an exception will occur here
_conditionSnippet[conditionName] = booleanExpression;
_assembly = null;
}
public static void AddMethod(string methodName, string methodSource)
{
if (_methodSnippet.ContainsKey(methodName))
throw new InvalidOperationException(string.Format("There is already a method called '{0}'", methodName));
if (methodName.StartsWith(DynamicConditionPrefix))
throw new InvalidOperationException(string.Format("'{0}' is not a valid method name because the '{1}' prefix is reserved for internal use with conditions", methodName, DynamicConditionPrefix));
StringBuilder src = new StringBuilder(CodeStart);
src.AppendFormat(MethodTemplate, methodName, methodSource);
src.Append(CodeEnd);
Trace.TraceError("SOURCE\r\n{0}", src);
Compile(src.ToString()); //if the condition is invalid an exception will occur here
_methodSnippet[methodName] = methodSource;
_assembly = null;
}
#endregion
#region use snippets
public static object InvokeMethod(string methodName, params object[] p)
{
DynamicBase _dynamicMethod = null;
if (_assembly == null)
{
Compile();
_dynamicMethod = _assembly.CreateInstance("Dynamo.Dynamic") as DynamicBase;
}
return _dynamicMethod.InvokeMethod(methodName, p);
}
public static bool Evaluate(string conditionName, params object[] p)
{
DynamicBase _dynamicCondition = null;
if (_assembly == null)
{
Compile();
_dynamicCondition = _assembly.CreateInstance("Dynamo.Dynamic") as DynamicBase;
}
return _dynamicCondition.EvaluateCondition(conditionName, p);
}
public static double Transform(string functionName, params object[] p)
{
DynamicBase _dynamicCondition = null;
if (_assembly == null)
{
Compile();
_dynamicCondition = _assembly.CreateInstance("Dynamo.Dynamic") as DynamicBase;
}
return _dynamicCondition.Transform(functionName, p);
}
#endregion
#region support routines
public static string ProduceConditionName(Guid conditionId)
{
StringBuilder cn = new StringBuilder();
foreach (char c in conditionId.ToString().ToCharArray()) if (char.IsLetterOrDigit(c)) cn.Append(c);
string conditionName = cn.ToString();
return string.Format("_dm_{0}",cn);
}
private static void Compile()
{
if (_assembly == null)
{
StringBuilder src = new StringBuilder(CodeStart);
foreach (KeyValuePair<string, string> kvp in _conditionSnippet)
src.AppendFormat(ConditionTemplate, DynamicConditionPrefix, kvp.Key, kvp.Value);
foreach (KeyValuePair<string, string> kvp in _methodSnippet)
src.AppendFormat(MethodTemplate, kvp.Key, kvp.Value);
src.Append(CodeEnd);
Trace.TraceError("SOURCE\r\n{0}", src);
_assembly = Compile(src.ToString());
}
}
private static Assembly Compile(string sourceCode)
{
CompilerParameters cp = new CompilerParameters();
cp.ReferencedAssemblies.AddRange(_references.ToArray());
cp.ReferencedAssemblies.Add(Assembly.GetExecutingAssembly().ManifestModule.FullyQualifiedName);
cp.CompilerOptions = "/target:library /optimize";
cp.GenerateExecutable = false;
cp.GenerateInMemory = true;
CompilerResults cr = (new CSharpCodeProvider()).CompileAssemblyFromSource(cp, sourceCode);
if (cr.Errors.Count > 0) throw new CompilerException(cr.Errors);
return cr.CompiledAssembly;
}
#endregion
public static bool HasItem(string methodName)
{
return _conditionSnippet.ContainsKey(methodName) || _methodSnippet.ContainsKey(methodName);
}
}
}
