c# - 如果使用自定义属性注入本机 PostSharp 属性将被忽略
问题描述
考虑以下代码:
[AttributeUsage(validOn: AttributeTargets.Property)]
public sealed class ExcludeAttribute : Attribute
{
}
[PSerializable]
public sealed class PsDependencyPropertyAttribute : TypeLevelAspect, IAspectProvider
{
public PsDependencyPropertyAttribute()
{
}
public IEnumerable<AspectInstance> ProvideAspects(object targetElement)
{
var targetType = (Type)targetElement;
//---
var introduceObfuscationAspect =
new CustomAttributeIntroductionAspect(
new ObjectConstruction(constructor: typeof(ObfuscationAttribute).GetConstructor(types: Type.EmptyTypes)));
introduceObfuscationAspect.CustomAttribute.NamedArguments.Add(key: "Feature", value: "renaming");
introduceObfuscationAspect.CustomAttribute.NamedArguments.Add(key: "Exclude", value: true);
introduceObfuscationAspect.CustomAttribute.NamedArguments.Add(key: "StripAfterObfuscation", value: true);
// add a Obfuscation attribute to every relevant property
foreach (var property
in targetType.GetProperties(
bindingAttr: BindingFlags.Public | BindingFlags.Static | BindingFlags.DeclaredOnly | BindingFlags.Instance)
.Where(
predicate: property =>
property.CanWrite &&
!property.IsDefined(attributeType: typeof(ExcludeAttribute), inherit: false)))
yield return new AspectInstance(targetElement: property, aspect: introduceObfuscationAspect);
//---
//! NATIVE PostSharp ATTRIBUTES DON'T GET PROCESSED IF THEY'RE INJECTED AT COMPILE TIME
var introduceDependencyPropertyAspect =
new CustomAttributeIntroductionAspect(
new ObjectConstruction(constructor: typeof(DependencyPropertyAttribute).GetConstructor(types: Type.EmptyTypes)));
// add a DependencyPropertyA attribute to every relevant property
foreach (var property
in targetType.GetProperties(
bindingAttr: BindingFlags.Public | BindingFlags.DeclaredOnly | BindingFlags.Instance)
.Where(
predicate: property =>
property.CanWrite &&
!property.IsDefined(attributeType: typeof(ExcludeAttribute), inherit: false)))
yield return new AspectInstance(targetElement: property, aspect: introduceDependencyPropertyAspect);
}
}
使用这个自定义属性确实注入了 2 个属性[DependencyProperty, Obfuscation(Feature = "renaming", Exclude = true, StripAfterObfuscation = true)]
,唯一的问题是这DependencyProperty
是一个 PostSharp 属性并且没有得到处理,只是注入了。这是合理的,因为自定义属性告诉 PS 只注入这两个属性,但是有没有办法在DependencyProperty
使用自定义属性注入 PS 时对其进行处理?
解决方案
您可以DependencyPropertyAttribute
直接提供作为目标属性的一个方面,而不是通过CustomAttributeIntroductionAspect
. 例如:
yield return new AspectInstance(targetElement: property, aspect: new DependencyPropertyAttribute());
这就是为什么DependencyPropertyAttribute
在作为属性引入时不处理的原因:
PostSharp 管道分几个阶段处理程序集。首先执行属性的处理,然后执行方面编织器。如果任何方面在此阶段发出新的自定义属性,则 PostSharp 将不再处理该属性,因为属性处理阶段已经完成。
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