将多个属性合并为一个属性-合并属性 [英] Combining multiple Attributes to a single Attribute - Merge Attributes
问题描述
在控件上，我使用了多个属性属性：
On a control I am using multiple attribute properties:
[Browsable(false)]
[Bindable(false)]
[EditorBrowsable(EditorBrowsableState.Never)]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
[Obsolete("", true)]
public new Boolean AllowDrop;
我也在许多其他控件属性上使用了这些属性。
I am using those properties on a lot of the other control properties as well.
我想知道是否有一种方法可以减少每次编写的代码量。
I am wondering if there is a way to reduce the amount of code to write each time.
可以像这样组合多个属性：
It would be nice if I could combine multiple attributes like this:
[Hidden(true)]
public new Boolean AllowDrop;
其中 Hidden 属性将包含所有以上属性。因此，只有一行代码。
Where the Hidden Property would include all the attributes above. So there is only 1 single line of code.
也许还有一种方法可以在宏或其他东西中组合属性？
Maybe there is also a way to combine the attributes in a macro or something?
我知道还有其他隐藏属性的方法，但是我选择了使用属性的方法。
I am aware that there are other ways of hiding properties but I chose the way of using attributes.
谢谢
推荐答案
这取决于使用该属性的框架。
It depends to the framework which is using the attribute.
按顺序组合属性是有意义的使用和解释属性的上下文。例如，对于使用.Net类型描述机制的上下文，您可以自定义类型描述。
Combining attributes can be meaningful in order to the context which uses and interprets attributes. For example for those contexts which use .Net Type Description mechanisms you can customize the type description which .Net returns to consumers.
可以为为此，可以使用标准.Net机制来输入类型，并为对象注册自定义类型描述符。
It's possible to provide custom metadata for types using the standard .Net mechanism for that purpose, registering a custom type descriptor for your object.
这种想法将以这种方式起作用，您可以为自己的对象创建自定义类型描述符类型。在自定义类型描述符中，您将为类型的属性返回自定义属性描述符，在属性描述符中，将为属性返回一组自定义属性。
The idea will work this way, you create a custom type descriptor for your type. In the custom type descriptor, you return custom property descriptors for the properties of your type and in the property descriptor, you return a custom set of attributes for the property.
该方法需要更多代码，但这确实很有趣，并且分享了一些有关如何为您的类型提供自定义元数据的好主意：
The approach requires more code, but it's really interesting and shares some good idea about how to provide custom metadata for your types:
IMetedataAttribute接口
此用法提供了创建MetaDataAttributes的标准方法。实现此接口的每个属性都将用作元数据，并且将使用在 Process 方法中返回的属性代替该属性：
The usage is providing an standard way to create MetaDataAttributes. Each attribute which implements this interface will be used as metadata and instead of the attribute, those one which it returns in Process method will be used:
public interface IMetadatAttribute
{
Attribute[] Process();
}
样本元数据属性
这是一个示例元数据属性，在处理该属性时会返回某些属性：
It's a sample metadata attribute which returns some attribute instead when processing the attribute:
public class MySampleMetadataAttribute : Attribute, IMetadatAttribute
{
public Attribute[] Process()
{
var attributes = new Attribute[]{
new BrowsableAttribute(false),
new EditorBrowsableAttribute(EditorBrowsableState.Never),
new BindableAttribute(false),
new DesignerSerializationVisibilityAttribute(
DesignerSerializationVisibility.Hidden),
new ObsoleteAttribute("", true)
};
return attributes;
}
}
属性描述符
自定义类型描述符将使用该类为属性提供自定义属性列表：
This class will be used by the custom type descriptor to provide a custom list of attributes for the property:
public class MyPropertyDescriptor : PropertyDescriptor
{
PropertyDescriptor original;
public MyPropertyDescriptor(PropertyDescriptor originalProperty)
: base(originalProperty) { original = originalProperty;}
public override AttributeCollection Attributes
{
get
{
var attributes = base.Attributes.Cast<Attribute>();
var result = new List<Attribute>();
foreach (var item in attributes)
{
if(item is IMetadatAttribute)
{
var attrs = ((IMetadatAttribute)item).Process();
if(attrs !=null )
{
foreach (var a in attrs)
result.Add(a);
}
}
else
result.Add(item);
}
return new AttributeCollection(result.ToArray());
}
}
// Implement other properties and methods simply using return original
// The implementation is trivial like this one:
// public override Type ComponentType
// {
// get { return original.ComponentType; }
// }
}
类型描述符
这是类型描述符，为您的类型提供自定义描述。在此示例中，它使用自定义属性描述符为类的属性提供自定义属性集：
This is the type descriptor which provides a custom description for your type. In this example it uses custom property descriptors to provide custom attributes set for the properties of your class:
public class MyTypeDescriptor : CustomTypeDescriptor
{
ICustomTypeDescriptor original;
public MyTypeDescriptor(ICustomTypeDescriptor originalDescriptor)
: base(originalDescriptor)
{
original = originalDescriptor;
}
public override PropertyDescriptorCollection GetProperties()
{
return this.GetProperties(new Attribute[] { });
}
public override PropertyDescriptorCollection GetProperties(Attribute[] attributes)
{
var properties = base.GetProperties(attributes).Cast<PropertyDescriptor>()
.Select(p => new MyPropertyDescriptor(p))
.ToArray();
return new PropertyDescriptorCollection(properties);
}
}
类型描述符提供程序
此类将在您的类型上方的属性中使用，以介绍我们作为该类型的元数据引擎创建的自定义类型描述符：
This class will be used in the attribute above your type to introduce the custom type descriptor which we created as the metadata engine for the type:
public class MyTypeDescriptionProvider : TypeDescriptionProvider
{
public MyTypeDescriptionProvider()
: base(TypeDescriptor.GetProvider(typeof(object))) { }
public override ICustomTypeDescriptor GetTypeDescriptor(Type objectType,
object instance)
{
ICustomTypeDescriptor baseDescriptor = base.GetTypeDescriptor(objectType, instance);
return new MyTypeDescriptor(baseDescriptor);
}
}
样本类
这是我的示例类，其 Name 属性使用 MySampleMetadataAttribute 并且该类本身已注册为使用我们的自定义类型描述符提供程序：
Here is my sample class which its Name property is decorated using MySampleMetadataAttribute and the class itself is registered to use our custom type descriptor provider:
[TypeDescriptionProvider(typeof(MyTypeDescriptionProvider))]
public class MySampleClass
{
public int Id { get; set; }
[MySampleMetadataAttribue]
[DisplayName("My Name")]
public string Name { get; set; }
}
要查看结果，足以创建该类的实例并查看 PropertyGrid 中的结果：
To see the result it's enough to create an instance of the class and see the result in PropertyGrid:
var o = new MySampleClass();
this.propertyGrid1.SelectedObject = o;
一些注意事项
- 可能不像您期望的那样简单。
- 这是一个冗长的答案，但其中包含一个完整的工作示例，说明如何将类型描述符应用于类型以提供自定义元数据。
- 该方法不适用于使用反射而不是类型描述的引擎。但这完全可以与例如
PropertyGrid控件一起使用，该控件可用于类型描述。
- Probably it's not as simple as you expected for such task. But it's working.
- It's a lengthy answer, but contains a complete working example of how you can apply type descriptors to your types to provide custom metadata.
- The approach will not work for engines which use reflection instead of type description. But it's completely working with for example
PropertyGridcontrol which works with type description.
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