为什么 C# 中没有“fieldof”或“methodof”运算符？ [关闭]

它们可以如下使用：

FieldInfo field = fieldof(string.Empty);
MethodInfo method1 = methodof(int.ToString);
MethodInfo method2 = methodof(int.ToString(IFormatProvider));

fieldof可以编译为 IL：

ldtoken <field>
call FieldInfo.GetFieldFromHandle

methodof可以编译为 IL：

ldtoken <method>
call MethodBase.GetMethodFromHandle

每当typeof使用运算符，您将获得完美的“查找所有引用”结果。不幸的是，一旦你进入字段或方法，你就会遇到令人讨厌的黑客攻击。我认为您可以执行以下操作...或者您可以返回按名称获取字段。

public static FieldInfo fieldof<T>(Expression<Func<T>> expression)
{
    MemberExpression body = (MemberExpression)expression.Body;
    return (FieldInfo)body.Member;
}

public static MethodInfo methodof<T>(Expression<Func<T>> expression)
{
    MethodCallExpression body = (MethodCallExpression)expression.Body;
    return body.Method;
}

public static MethodInfo methodof(Expression<Action> expression)
{
    MethodCallExpression body = (MethodCallExpression)expression.Body;
    return body.Method;
}

public static void Test()
{
    FieldInfo field = fieldof(() => string.Empty);
    MethodInfo method1 = methodof(() => default(string).ToString());
    MethodInfo method2 = methodof(() => default(string).ToString(default(IFormatProvider)));
    MethodInfo method3 = methodof(() => default(List<int>).Add(default(int)));
}

实际上，您可以避免同时使用反射和 lambda (.NET Framework 2.0)。考虑下面的类：

public class methodof<T>
{
    private MethodInfo method;

    public methodof(T func)
    {
        Delegate del = (Delegate)(object)func;
        this.method = del.Method;
    }

    public static implicit operator methodof<T>(T methodof)
    {
        return new methodof<T>(methodof);
    }

    public static implicit operator MethodInfo(methodof<T> methodof)
    {
        return methodof.method;
    }
}

它的用法：

MethodInfo writeln = (methodof<Action>)Console.WriteLine;
MethodInfo parse = (methodof<Func<string, int>>)int.Parse;