Practical example of Dynamic method?
I want to learn dynamic method and its practical example using c#.
Is there any relation between dynamic method and Reflection?
Please help me.
Answer
We are using Dynamic methods for speed up Reflection. Here is code of our reflection optimizer. it is only 10% slower than direct call and 2000 times faster that reflection call
public class ReflectionEmitPropertyAccessor
{
private readonly bool canRead;
private readonly bool canWrite;
private IPropertyAccessor emittedPropertyAccessor;
private readonly string propertyName;
private readonly Type propertyType;
private readonly Type targetType;
private Dictionary<Type,OpCode> typeOpCodes;
public ReflectionEmitPropertyAccessor(Type targetType, string property)
{
this.targetType = targetType;
propertyName = property;
var propertyInfo = targetType.GetProperty(property);
if (propertyInfo == null)
{
throw new ReflectionOptimizerException(string.Format("Property \"{0}\" is not found in type "+ "{1}.", property, targetType));
}
canRead = propertyInfo.CanRead;
canWrite = propertyInfo.CanWrite;
propertyType = propertyInfo.PropertyType;
}
public bool CanRead
{
get { return canRead; }
}
public bool CanWrite
{
get { return canWrite; }
}
public Type TargetType
{
get { return targetType; }
}
public Type PropertyType
{
get { return propertyType; }
}
#region IPropertyAccessor Members
public object Get(object target)
{
if (canRead)
{
if (emittedPropertyAccessor == null)
{
Init();
}
if (emittedPropertyAccessor != null) return emittedPropertyAccessor.Get(target);
}
else
{
throw new ReflectionOptimizerException(string.Format("У свойства \"{0}\" нет метода get.", propertyName));
}
throw new ReflectionOptimizerException("Fail initialize of " + GetType().FullName);
}
public void Set(object target, object value)
{
if (canWrite)
{
if (emittedPropertyAccessor == null)
{
Init();
}
if (emittedPropertyAccessor != null) emittedPropertyAccessor.Set(target, value);
}
else
{
throw new ReflectionOptimizerException(string.Format("Property \"{0}\" does not have method set.", propertyName));
}
throw new ReflectionOptimizerException("Fail initialize of " + GetType().FullName);
}
#endregion
private void Init()
{
InitTypeOpCodes();
var assembly = EmitAssembly();
emittedPropertyAccessor = assembly.CreateInstance("Property") as IPropertyAccessor;
if (emittedPropertyAccessor == null)
{
throw new ReflectionOptimizerException("Shit happense in PropertyAccessor.");
}
}
private void InitTypeOpCodes()
{
typeOpCodes = new Dictionary<Type, OpCode>
{
{typeof (sbyte), OpCodes.Ldind_I1},
{typeof (byte), OpCodes.Ldind_U1},
{typeof (char), OpCodes.Ldind_U2},
{typeof (short), OpCodes.Ldind_I2},
{typeof (ushort), OpCodes.Ldind_U2},
{typeof (int), OpCodes.Ldind_I4},
{typeof (uint), OpCodes.Ldind_U4},
{typeof (long), OpCodes.Ldind_I8},
{typeof (ulong), OpCodes.Ldind_I8},
{typeof (bool), OpCodes.Ldind_I1},
{typeof (double), OpCodes.Ldind_R8},
{typeof (float), OpCodes.Ldind_R4}
};
}
private Assembly EmitAssembly()
{
var assemblyName = new AssemblyName {Name = "PropertyAccessorAssembly"};
var newAssembly = Thread.GetDomain().DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run);
var newModule = newAssembly.DefineDynamicModule("Module");
var dynamicType = newModule.DefineType("Property", TypeAttributes.Public);
dynamicType.AddInterfaceImplementation(typeof(IPropertyAccessor));
dynamicType.DefineDefaultConstructor(MethodAttributes.Public);
var getParamTypes = new[] { typeof(object) };
var getReturnType = typeof(object);
var getMethod = dynamicType.DefineMethod("Get",
MethodAttributes.Public | MethodAttributes.Virtual,
getReturnType,
getParamTypes);
var getIL = getMethod.GetILGenerator();
var targetGetMethod = targetType.GetMethod("get_" + propertyName);
if (targetGetMethod != null)
{
getIL.DeclareLocal(typeof(object));
getIL.Emit(OpCodes.Ldarg_1); //Load the first argument
getIL.Emit(OpCodes.Castclass, targetType); //Cast to the source type
getIL.EmitCall(OpCodes.Call, targetGetMethod, null); //Get the property value
if (targetGetMethod.ReturnType.IsValueType)
{
getIL.Emit(OpCodes.Box, targetGetMethod.ReturnType); //Box
}
getIL.Emit(OpCodes.Stloc_0); //Store it
getIL.Emit(OpCodes.Ldloc_0);
}
else
{
getIL.ThrowException(typeof(MissingMethodException));
}
getIL.Emit(OpCodes.Ret);
var setParamTypes = new[] { typeof(object), typeof(object) };
const Type setReturnType = null;
var setMethod = dynamicType.DefineMethod("Set",
MethodAttributes.Public | MethodAttributes.Virtual,
setReturnType,
setParamTypes);
var setIL = setMethod.GetILGenerator();
var targetSetMethod = targetType.GetMethod("set_" + propertyName);
if (targetSetMethod != null)
{
Type paramType = targetSetMethod.GetParameters()[0].ParameterType;
setIL.DeclareLocal(paramType);
setIL.Emit(OpCodes.Ldarg_1); //Load the first argument //(target object)
setIL.Emit(OpCodes.Castclass, targetType); //Cast to the source type
setIL.Emit(OpCodes.Ldarg_2); //Load the second argument
//(value object)
if (paramType.IsValueType)
{
setIL.Emit(OpCodes.Unbox, paramType); //Unbox it
if (typeOpCodes.ContainsKey(paramType)) //and load
{
var load = typeOpCodes[paramType];
setIL.Emit(load);
}
else
{
setIL.Emit(OpCodes.Ldobj, paramType);
}
}
else
{
setIL.Emit(OpCodes.Castclass, paramType); //Cast class
}
setIL.EmitCall(OpCodes.Callvirt,targetSetMethod, null); //Set the property value
}
else
{
setIL.ThrowException(typeof(MissingMethodException));
}
setIL.Emit(OpCodes.Ret);
// Load the type
dynamicType.CreateType();
return newAssembly;
}
}
implementation is aggregated from different sources and main is this CodeProject article.