Question

让我们假设以下界面

interface Foo {
    void Bar();
    void Bar(string str);
    int Bar(int i);
    IEnumerable<string> Bar1();
    void Bar1(string str);
    void Bar1(int i);
    //...
}

let假定一个方法接收方法信息。如何检查此方法信息是否与界面上的特定方法有关？

void DoStuff(MethodInfo method){
     //basically in pseudo code
     if(method is Foo.Bar(string)){
         //dostuff
     }
}

离我最近的是类似的东西

if(method.ReflectedType.IsAssignableFrom(typeof(Foo))
   && method.Name == nameof(Foo.Bar) 
   && method.GetParameters().Length == 1
   && method.GetParameters()[0].ParameterType == typeof(string))

但是，这很冗长，不能重构。

在下一步中，我想要一个可以检查MethodInfo列表的方法。像

bool IsIn(this MethodInfo self, IEnumerable<??> methods){
     //again, pseudo code
     return methods.Any(m => m is self);
}

可以很容易地使用

bool b = methodInfo.IsIn(new [] {
    Foo.Bar(str),
    Foo.Bar1(int)
});

Answer 1

我想到了这个

    public static bool Is<T>(this MethodInfo self, Expression<Action<T>> selector, bool strict = false)
    {
        var body = (selector.Body as MethodCallExpression);
        if (body == null) return false;
        var methodName = body.Method.Name;
        if (self.Name != methodName) return false;
        if (strict && self.ReflectedType != body.Method.ReflectedType) return false;
        var parameterInfos = body.Method.GetParameters();
        var parameterCount = parameterInfos.Length;
        var parameters = self.GetParameters();
        if (parameters.Length != parameterCount) return false;
        return !parameters.Where((t, i) =>
            t.ParameterType != parameterInfos[i].ParameterType).Any();
    }

完成对某些不同方案的单元测试。感谢@thehennyy链接文章。我意识到我没有涵盖所有极端情况。就我所需要的就足够了。

   public class IsTests
{
    [Fact]
    public void IsTheBarMethodWithOneIntParameterFromInterface()
    {
        var method = typeof(IFoo).GetMethod(nameof(IFoo.Bar), new []{typeof(int)});

        method.Is<IFoo>(m => m.Bar(default(int)))
            .Should().BeTrue("This is the method I intended");

        method.Is<IFoo>(m => m.Bar(default(int)), strict: true)
            .Should().BeTrue("This is the method I intended");
    }

    [Fact]
    public void IsTheBarMethodWithOneIntParameterFromImplementingClass()
    {
        var method = typeof(Foo).GetMethod(nameof(Foo.Bar), new[] { typeof(int) });

        method.Is<IFoo>(m => m.Bar(default(int)))
            .Should().BeTrue("This is the method I intended");

        method.Is<IFoo>(m => m.Bar(default(int)), strict: true)
            .Should().BeFalse("In strict mode the reference of the interface can not be used to identify the concrete implementation.");
    }

    [Fact]
    public void IsNotTheBarMethodWithOneStringParameter()
    {
        var method = typeof(Foo).GetMethod(nameof(Foo.Bar), new[] { typeof(int) });

        method.Is<IFoo>(m => m.Bar(default(string)))
            .Should().BeFalse("This is not the method I intended");


        method.Is<IFoo>(m => m.Bar(default(string)), strict:true)
            .Should().BeFalse("This is not the method I intended");
    }

    [Fact]
    public void IsTheBarMethodWithAnInterfaceParameter()
    {
        var method = typeof(Foo).GetMethod(nameof(Foo.Bar), new[] { typeof(IFoo) });

        method.Is<Foo>(m => m.Bar(default(IFoo)))
            .Should().BeTrue("This is the method I intended");


        method.Is<Foo>(m => m.Bar(default(IFoo)), strict:true)
            .Should().BeTrue("This is the method I intended");
    }

    [Fact]
    public void IsTheOnlyMethodWithTwoParamters()
    {
        var method = typeof(Foo).GetMethod(nameof(Foo.Bar), new[] { typeof(int), typeof(int) });

        method.Is<Foo>(m => m.Bar(default, default))
            .Should().BeTrue("This is the method I intended");

        method.Is<Foo>(m => m.Bar(default, default), strict: true)
            .Should().BeTrue("This is the method I intended");

        method.Is<IFoo>(m => m.Bar(default, default))
            .Should().BeTrue("This is the method I intended");

        method.Is<IFoo>(m => m.Bar(default, default), strict: true)
            .Should().BeFalse("In strict mode a interface reference can not be used on a concrete method");
    }

    [Fact]
    public void IsTheMethodThatHasUnreachableOverloads()
    {
        //the next line would give a AmbiguousMatchException at run time 
        //var method = typeof(Quux).GetMethod(nameof(Qux<int>.Bar), new[] {typeof(int), typeof(int) });

        //so, I used some helper function I found on 
        //http://blog.functionalfun.net/2009/10/getting-methodinfo-of-generic-method.html
        var method = MethodInfoExtension.GetMethodInfo(() => new Quux().Bar(1, 1));

        method.Is<Qux<int>>(m => m.Bar(default, default))
            .Should().BeTrue("This is the method I intended");
    }

    [Fact]
    public void IsTheMethodThatHasUnreachableOverloads_2()
    {
        var method = MethodInfoExtension.GetMethodInfo(() => new Quux().Bar(1, 1));

        //on could also specify a instance directly instead of default(type),
        method.Is<Qux<int>>(m => m.Bar(0, 0))
            .Should().BeTrue("This is the method I intended");
    }

    [Fact]
    public void IsTheMethodFromTheSpecificInterface()
    {
        var method = MethodInfoExtension.GetMethodInfo(() => (new Corge() as Grault).DoStuff());

        method.Is<Grault>(m => m.DoStuff(), strict: true)
            .Should().BeTrue("This is the method I intended");

        method.Is<Garply>(m => m.DoStuff(), strict: true)
            .Should().BeFalse("It is not the method I intended");
    }
}

public static class MethodInfoExtension
{
    public static bool Is<T>(this MethodInfo self, Expression<Action<T>> selector, bool strict = false)
    {
        var body = (selector.Body as MethodCallExpression);
        if (body == null) return false;
        var methodName = body.Method.Name;
        if (self.Name != methodName) return false;
        if (strict && self.ReflectedType != body.Method.ReflectedType) return false;
        var parameterInfos = body.Method.GetParameters();
        var parameterCount = parameterInfos.Length;
        var parameters = self.GetParameters();
        if (parameters.Length != parameterCount) return false;
        return !parameters.Where((t, i) =>
            t.ParameterType != parameterInfos[i].ParameterType).Any();
    }

    public static MethodInfo GetMethodInfo(Expression<Action> expression)
    {
        return GetMethodInfo((LambdaExpression)expression);
    }

    #region GetMethodInfo
    //Helper methods found on //http://blog.functionalfun.net/2009/10/getting-methodinfo-of-generic-method.html
    public static MethodInfo GetMethodInfo<T>(Expression<Action<T>> expression)
    {
        return GetMethodInfo((LambdaExpression)expression);
    }

    public static MethodInfo GetMethodInfo<T, TResult>(Expression<Func<T, TResult>> expression)
    {
        return GetMethodInfo((LambdaExpression)expression);
    }

    public static MethodInfo GetMethodInfo(LambdaExpression expression)
    {
        MethodCallExpression outermostExpression = expression.Body as MethodCallExpression;

        if (outermostExpression == null)
        {
            throw new ArgumentException("Invalid Expression. Expression should consist of a Method call only.");
        }

        return outermostExpression.Method;
    }
    #endregion
}

interface IFoo
{
    void Bar();
    void Bar(string str);
    int Bar(int i);
    void Bar(int i1, int i2);
    void Bar(IFoo foo);
    IEnumerable<string> Bar1();
    void Bar1(string str);
    void Bar1(int i);
}

class Foo : IFoo
{
    public void Bar() { }
    public void Bar(string str) { }
    public int Bar(int i) => default;
    public void Bar(int i1, int i2) { }
    public void Bar(IFoo foo) { }
    public IEnumerable<string> Bar1() => default;
    public void Bar1(string str) { }
    public void Bar1(int i) { }
}

class Qux<T> 
{
    public void Bar(int x, T y) { }
    public void Bar(T x, int y) { }
    public void Bar(int x, int y) { }
}

class Quux : Qux<int>
{
}

interface Grault
{
    void DoStuff();
}

interface Garply
{
    void DoStuff();
}

class Corge : Grault, Garply
{
    void Grault.DoStuff() { }
    void Garply.DoStuff() { }
}

如何检查MethodInfo是否为特定的接口方法

1 个答案: