Question

我想将类型数组传递给属性，我尝试这样做

class CustomAttribute: Attribute 
{
   Type[] included;
   Type[] excluded;
}

[CustomAttribute{included = new Type[] {typeof(ComponentA)}, 
                 excluded = new Type[] {typeof(ComponentB)} }]//dont work  
class Processor 
{
   // something here
}

但VS显示不能传递属性中的类型。

有人知道如何解决此问题或最终的解决方法吗？

Answer 1

看起来这与数组无关，而是与你的一般语法有关。您使用{ }作为属性参数而不是( )，并且您的属性没有公共属性，属性中的命名参数需要这些属性。此外，您的属性类不使用[AttributeUsage(...)]。

以下是编译的完整示例：

using System;

[AttributeUsage(AttributeTargets.All)]
class CustomAttribute : Attribute 
{
    public Type[] Included { get; set; }
    public Type[] Excluded { get; set; }
}

[CustomAttribute(Included = new Type[] { typeof(string) },
                 Excluded = new Type[] { typeof(int), typeof(bool) })]
class Processor 
{
}

让事情更简洁：

您可以提供带参数的构造函数
您可以使用new[]代替new Type[]

所以：

using System;

[AttributeUsage(AttributeTargets.All)]
class CustomAttribute : Attribute 
{
    public Type[] Included { get; set; }
    public Type[] Excluded { get; set; }

    // Keep a parameterless constructor to allow for
    // named attribute arguments
    public CustomAttribute()
    {
    }

    public CustomAttribute(Type[] included, Type[] excluded)
    {
        Included = included;
        Excluded = excluded;
    }
}

[CustomAttribute(new[] { typeof(string) }, new[] { typeof(int), typeof(bool) })]
class Processor 
{
    // Provide the named version still works
    [CustomAttribute(Included = new[] { typeof(string) },
                     Excluded = new[] { typeof(int), typeof(bool) })]
    public void Method()
    {
    }
}

Answer 2

缺少一些访问修饰符，并且您没有正确使用该属性。

您需要在`CustomAttribute```类中公开included和exluded属性：

class CustomAttribute: Attribute 
{
   public Type[] Included { get; set; }
   public Type[] Excluded { get; set; }
}

为属性成员指定值时，需要使用()而不是{}

你的专栏是：

[CustomAttribute{included = new Type[] {typeof(ComponentA)},excluded = new Type[] {typeof(ComponentB)} }]

应该是：

[CustomAttribute(Included = new Type[] {typeof(ComponentA)}, Excluded = new Type[] {typeof(ComponentB)} )]

请注意(之后的CustomAttribute和)之前的]。

Answer 3

您的In [39]: %timeit (dark1(df)) 1 loop, best of 3: 15.4 s per loop In [40]: %timeit (dark2(df)) 10 loops, best of 3: 52.7 ms per loop In [41]: %timeit (jez1(df)) 10 loops, best of 3: 38.8 ms per loop In [42]: %timeit (jez2(df)) 10 loops, best of 3: 44.9 ms per loop字段是私密的。考虑使用公共属性而不是公开字段。 "Why it is preferable to use public properties instead of public fields"

由于您将参数传递给属性的语法不正确，因此您的代码无法编译。你需要：

Type

在将参数（而不是class CustomAttribute: Attribute { public Type[] Included { get; set; } public Type[] Excluded { get; set; } } [CustomAttribute(Included = new Type[] {typeof(ComponentA)}, Excluded = new Type[] {typeof(ComponentB)} )] class Processor { // something here }）传递给{}构造函数时，请注意括号。

属性中的类型数组

3 个答案: