给定一个类型、一个名称和一个签名,我如何查找名称为名称的成员 和签名 signature 使用 7.4 的 C# 规则(7.4 是 C# 语言规范中的章节号)(或者至少是其中的一部分……假设我可以接受完全匹配,没有转换/转换)在运行时?我需要得到一个 MethodInfo
/PropertyInfo
/... 因为那时我必须将它与反射一起使用(更准确地说,我正在尝试构建一个 Expression.ForEach
构建器(一个能够创建表示 foreach
语句的表达式树的工厂),并且与我拥有的 C# foreach
完美像素能够进行 duck-typing 并搜索 GetEnumerator
方法(在集合中)、Current
属性和 MoveNext
方法(在集合中枚举器),如 8.8.4 中所写)
问题(问题的一个例子)
class C1
{
public int Current { get; set; }
public object MoveNext()
{
return null;
}
}
class C2 : C1
{
public new long Current { get; set; }
public new bool MoveNext()
{
return true;
}
}
class C3 : C2
{
}
var m = typeof(C3).GetMethods(); // I get both versions of MoveNext()
var p = typeof(C3).GetProperties(); // I get both versions of Current
很明显,如果我尝试 typeof(C3).GetProperty("Current")
,我会得到一个 AmbiguousMatchException
异常。
接口(interface)存在类似但不同的问题:
interface I0
{
int Current { get; set; }
}
interface I1 : I0
{
new long Current { get; set; }
}
interface I2 : I1, I0
{
new object Current { get; set; }
}
interface I3 : I2
{
}
在这里,如果我尝试执行 typeof(I3).GetProperties()
,我不会获得 Current
属性(这是已知的,参见示例GetProperties() to return all properties for an interface inheritance hierarchy ),但我不能简单地扁平化接口(interface),因为那样我就不知道谁在隐藏谁。
我知道这个问题可能在 Microsoft.CSharp.RuntimeBinder
命名空间(在 Microsoft.CSharp
程序集中声明)的某处得到解决。这是因为我正在尝试使用 C# 规则,当你有动态方法调用时,成员查找是必要的,但我找不到任何东西(然后我会得到一个 Expression
或者直接调用)。
经过一番思考,很明显 Microsoft.VisualBasic
程序集中有类似的东西。 VB.NET 支持后期绑定(bind)。它在 Microsoft.VisualBasic.CompilerServices.NewLateBinding
中,但它不公开后期有界方法。
最佳答案
(注意:隐藏 = 隐藏 = C# 中的方法/属性/事件定义中的新内容)
没有人回应,所以我将在此期间发布我编写的代码。我讨厌发布 400 行代码,但我想完整。主要有两种方法:GetVisibleMethods
和 GetVisibleProperties
.它们是 Type
的扩展方法类(class)。它们将返回类型的公共(public)可见(非阴影/非覆盖)方法/属性。他们甚至应该处理 VB.NET 程序集(VB.NET 通常使用 hide-by-name
阴影而不是像 C# 那样使用 hidebysig
)。他们将结果缓存在两个静态集合中(Methods
和 Properties
)。该代码适用于 C# 4.0,所以我使用 ConcurrentDictionary<T, U>
.如果您使用的是 C# 3.5,则可以将其替换为 Dictionary<T, U>
但你必须用 lock
来保护它() { } 当您从中读取和写入时。
它是如何工作的?它通过递归工作(我知道递归通常是不好的,但我希望没有人会创建 1.000 级继承链)。
对于“真正的”类型(非接口(interface)),它向上走一层(使用递归,所以这一层向上可以向上一层等等)并且,从返回的方法/属性列表中,它删除了重载/隐藏的方法/属性。
对于接口(interface),它有点复杂。 Type.GetInterfaces()
返回所有被继承的接口(interface),忽略是直接继承还是间接继承。对于这些接口(interface)中的每一个,都会计算(通过递归)声明的方法/属性的列表。此列表与接口(interface)隐藏的方法/属性列表配对(HashSet<MethodInfo>
/HashSet<PropertyInfo>
)。这些被一个接口(interface)或另一个接口(interface)隐藏的方法/属性将从接口(interface)返回的所有其他方法/属性中删除(因此,如果您有 I1
和 Method1(int)
, I2
继承自 I1
重新声明 Method1(int)
和这样做会隐藏 I1.Method1
和 I3
继承自 I1
和 I2
,I2
隐藏 I1.Method1
的事实将应用于从探索 I1
返回的方法,因此删除 I1.Method1(int)
(发生这种情况是因为我没有为接口(interface)生成继承映射,我只是看看隐藏了什么))。
从返回的方法/属性集合中,可以使用 Linq 找到要查找的方法/属性。请注意,对于接口(interface),您可以找到多个具有给定签名的方法/属性。一个例子:
interface I1
{
void Method1();
}
interface I2
{
void Method1();
}
interface I3 : I1, I2
{
}
I3
将返回两个 Method1()
.
代码:
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
public static class TypeEx
{
/// <summary>
/// Type, Tuple<Methods of type, (for interfaces)methods of base interfaces shadowed>
/// </summary>
public static readonly ConcurrentDictionary<Type, Tuple<MethodInfo[], HashSet<MethodInfo>>> Methods = new ConcurrentDictionary<Type, Tuple<MethodInfo[], HashSet<MethodInfo>>>();
/// <summary>
/// Type, Tuple<Properties of type, (for interfaces)properties of base interfaces shadowed>
/// </summary>
public static readonly ConcurrentDictionary<Type, Tuple<PropertyInfo[], HashSet<PropertyInfo>>> Properties = new ConcurrentDictionary<Type, Tuple<PropertyInfo[], HashSet<PropertyInfo>>>();
public static MethodInfo[] GetVisibleMethods(this Type type)
{
if (type.IsInterface)
{
return (MethodInfo[])type.GetVisibleMethodsInterfaceImpl().Item1.Clone();
}
return (MethodInfo[])type.GetVisibleMethodsImpl().Clone();
}
public static PropertyInfo[] GetVisibleProperties(this Type type)
{
if (type.IsInterface)
{
return (PropertyInfo[])type.GetVisiblePropertiesInterfaceImpl().Item1.Clone();
}
return (PropertyInfo[])type.GetVisiblePropertiesImpl().Clone();
}
private static MethodInfo[] GetVisibleMethodsImpl(this Type type)
{
Tuple<MethodInfo[], HashSet<MethodInfo>> tuple;
if (Methods.TryGetValue(type, out tuple))
{
return tuple.Item1;
}
var methods = type.GetMethods(BindingFlags.DeclaredOnly | BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public);
if (type.BaseType == null)
{
Methods.TryAdd(type, Tuple.Create(methods, (HashSet<MethodInfo>)null));
return methods;
}
var baseMethods = type.BaseType.GetVisibleMethodsImpl().ToList();
foreach (var method in methods)
{
if (method.IsHideByName())
{
baseMethods.RemoveAll(p => p.Name == method.Name);
}
else
{
int numGenericArguments = method.GetGenericArguments().Length;
var parameters = method.GetParameters();
baseMethods.RemoveAll(p =>
{
if (!method.EqualSignature(numGenericArguments, parameters, p))
{
return false;
}
return true;
});
}
}
if (baseMethods.Count == 0)
{
Methods.TryAdd(type, Tuple.Create(methods, (HashSet<MethodInfo>)null));
return methods;
}
var methods3 = new MethodInfo[methods.Length + baseMethods.Count];
Array.Copy(methods, 0, methods3, 0, methods.Length);
baseMethods.CopyTo(methods3, methods.Length);
Methods.TryAdd(type, Tuple.Create(methods3, (HashSet<MethodInfo>)null));
return methods3;
}
private static Tuple<MethodInfo[], HashSet<MethodInfo>> GetVisibleMethodsInterfaceImpl(this Type type)
{
Tuple<MethodInfo[], HashSet<MethodInfo>> tuple;
if (Methods.TryGetValue(type, out tuple))
{
return tuple;
}
var methods = type.GetMethods(BindingFlags.DeclaredOnly | BindingFlags.Instance | BindingFlags.Public);
var baseInterfaces = type.GetInterfaces();
if (baseInterfaces.Length == 0)
{
tuple = Tuple.Create(methods, new HashSet<MethodInfo>());
Methods.TryAdd(type, tuple);
return tuple;
}
var baseMethods = new List<MethodInfo>();
var baseMethodsTemp = new MethodInfo[baseInterfaces.Length][];
var shadowedMethods = new HashSet<MethodInfo>();
for (int i = 0; i < baseInterfaces.Length; i++)
{
var tuple2 = baseInterfaces[i].GetVisibleMethodsInterfaceImpl();
baseMethodsTemp[i] = tuple2.Item1;
shadowedMethods.UnionWith(tuple2.Item2);
}
for (int i = 0; i < baseInterfaces.Length; i++)
{
baseMethods.AddRange(baseMethodsTemp[i].Where(p => !shadowedMethods.Contains(p)));
}
foreach (var method in methods)
{
if (method.IsHideByName())
{
baseMethods.RemoveAll(p =>
{
if (p.Name == method.Name)
{
shadowedMethods.Add(p);
return true;
}
return false;
});
}
else
{
int numGenericArguments = method.GetGenericArguments().Length;
var parameters = method.GetParameters();
baseMethods.RemoveAll(p =>
{
if (!method.EqualSignature(numGenericArguments, parameters, p))
{
return false;
}
shadowedMethods.Add(p);
return true;
});
}
}
if (baseMethods.Count == 0)
{
tuple = Tuple.Create(methods, shadowedMethods);
Methods.TryAdd(type, tuple);
return tuple;
}
var methods3 = new MethodInfo[methods.Length + baseMethods.Count];
Array.Copy(methods, 0, methods3, 0, methods.Length);
baseMethods.CopyTo(methods3, methods.Length);
tuple = Tuple.Create(methods3, shadowedMethods);
Methods.TryAdd(type, tuple);
return tuple;
}
private static PropertyInfo[] GetVisiblePropertiesImpl(this Type type)
{
Tuple<PropertyInfo[], HashSet<PropertyInfo>> tuple;
if (Properties.TryGetValue(type, out tuple))
{
return tuple.Item1;
}
var properties = type.GetProperties(BindingFlags.DeclaredOnly | BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public);
if (type.BaseType == null)
{
Properties.TryAdd(type, Tuple.Create(properties, (HashSet<PropertyInfo>)null));
return properties;
}
var baseProperties = type.BaseType.GetVisiblePropertiesImpl().ToList();
foreach (var property in properties)
{
if (property.IsHideByName())
{
baseProperties.RemoveAll(p => p.Name == property.Name);
}
else
{
var indexers = property.GetIndexParameters();
baseProperties.RemoveAll(p =>
{
if (!property.EqualSignature(indexers, p))
{
return false;
}
return true;
});
}
}
if (baseProperties.Count == 0)
{
Properties.TryAdd(type, Tuple.Create(properties, (HashSet<PropertyInfo>)null));
return properties;
}
var properties3 = new PropertyInfo[properties.Length + baseProperties.Count];
Array.Copy(properties, 0, properties3, 0, properties.Length);
baseProperties.CopyTo(properties3, properties.Length);
Properties.TryAdd(type, Tuple.Create(properties3, (HashSet<PropertyInfo>)null));
return properties3;
}
private static Tuple<PropertyInfo[], HashSet<PropertyInfo>> GetVisiblePropertiesInterfaceImpl(this Type type)
{
Tuple<PropertyInfo[], HashSet<PropertyInfo>> tuple;
if (Properties.TryGetValue(type, out tuple))
{
return tuple;
}
var properties = type.GetProperties(BindingFlags.DeclaredOnly | BindingFlags.Instance | BindingFlags.Public);
var baseInterfaces = type.GetInterfaces();
if (baseInterfaces.Length == 0)
{
tuple = Tuple.Create(properties, new HashSet<PropertyInfo>());
Properties.TryAdd(type, tuple);
return tuple;
}
var baseProperties = new List<PropertyInfo>();
var basePropertiesTemp = new PropertyInfo[baseInterfaces.Length][];
var shadowedProperties = new HashSet<PropertyInfo>();
for (int i = 0; i < baseInterfaces.Length; i++)
{
var tuple2 = baseInterfaces[i].GetVisiblePropertiesInterfaceImpl();
basePropertiesTemp[i] = tuple2.Item1;
shadowedProperties.UnionWith(tuple2.Item2);
}
for (int i = 0; i < baseInterfaces.Length; i++)
{
baseProperties.AddRange(basePropertiesTemp[i].Where(p => !shadowedProperties.Contains(p)));
}
foreach (var property in properties)
{
if (property.IsHideByName())
{
baseProperties.RemoveAll(p =>
{
if (p.Name == property.Name)
{
shadowedProperties.Add(p);
return true;
}
return false;
});
}
else
{
var indexers = property.GetIndexParameters();
baseProperties.RemoveAll(p =>
{
if (!property.EqualSignature(indexers, p))
{
return false;
}
shadowedProperties.Add(p);
return true;
});
}
}
if (baseProperties.Count == 0)
{
tuple = Tuple.Create(properties, shadowedProperties);
Properties.TryAdd(type, tuple);
return tuple;
}
var properties3 = new PropertyInfo[properties.Length + baseProperties.Count];
Array.Copy(properties, 0, properties3, 0, properties.Length);
baseProperties.CopyTo(properties3, properties.Length);
tuple = Tuple.Create(properties3, shadowedProperties);
Properties.TryAdd(type, tuple);
return tuple;
}
private static bool EqualSignature(this MethodInfo method1, int numGenericArguments1, ParameterInfo[] parameters1, MethodInfo method2)
{
// To shadow by signature a method must have same name, same number of
// generic arguments, same number of parameters and same parameters' type
if (method1.Name != method2.Name)
{
return false;
}
if (numGenericArguments1 != method2.GetGenericArguments().Length)
{
return false;
}
var parameters2 = method2.GetParameters();
if (!parameters1.EqualParameterTypes(parameters2))
{
return false;
}
return true;
}
private static bool EqualSignature(this PropertyInfo property1, ParameterInfo[] indexers1, PropertyInfo property2)
{
// To shadow by signature a property must have same name,
// same number of indexers and same indexers' type
if (property1.Name != property2.Name)
{
return false;
}
var parameters2 = property1.GetIndexParameters();
if (!indexers1.EqualParameterTypes(parameters2))
{
return false;
}
return true;
}
private static bool EqualParameterTypes(this ParameterInfo[] parameters1, ParameterInfo[] parameters2)
{
if (parameters1.Length != parameters2.Length)
{
return false;
}
for (int i = 0; i < parameters1.Length; i++)
{
if (parameters1[i].IsOut != parameters2[i].IsOut)
{
return false;
}
if (parameters1[i].ParameterType.IsGenericParameter)
{
if (!parameters2[i].ParameterType.IsGenericParameter)
{
return false;
}
if (parameters1[i].ParameterType.GenericParameterPosition != parameters2[i].ParameterType.GenericParameterPosition)
{
return false;
}
}
else if (parameters1[i].ParameterType != parameters2[i].ParameterType)
{
return false;
}
}
return true;
}
private static bool IsHideByName(this MethodInfo method)
{
if (!method.Attributes.HasFlag(MethodAttributes.HideBySig) && (!method.Attributes.HasFlag(MethodAttributes.Virtual) || method.Attributes.HasFlag(MethodAttributes.NewSlot)))
{
return true;
}
return false;
}
private static bool IsHideByName(this PropertyInfo property)
{
var get = property.GetGetMethod();
if (get != null && get.IsHideByName())
{
return true;
}
var set = property.GetSetMethod();
if (set != null && set.IsHideByName())
{
return true;
}
return false;
}
}
关于c# - 在运行时解析成员名称,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/11413313/