返回嵌套的通用表达式<Func <T,bool >>

Question

错误消息"找不到类型或命名空间名称'T'."

???

public static Expression<Func<T, bool>> MakeFilter(string prop, object val)
{
    ParameterExpression pe = Expression.Parameter(typeof(T), "p");
    PropertyInfo pi = typeof(T).GetProperty(prop);
    MemberExpression me = Expression.MakeMemberAccess(pe, pi);
    ConstantExpression ce = Expression.Constant(val);
    BinaryExpression be = Expression.Equal(me, ce);
    return Expression.Lambda<Func<T, bool>>(be, pe);
}

相关链接:

使用反射来解决Linqed属性

http://social.msdn.microsoft.com/forums/en-US/linqprojectgeneral/thread/df9dba6e-4615-478d-9d8a-9fd80c941ea2/

通用Func <T>的运行时创建

Answer 1

您需要使方法本身通用:

public static Expression<Func<T, bool>> MakeFilter<T>(string prop, object val)
                                                  -+-
                                                   ^
                                                   +- this