我正在创建一个看起来有点像单元测试框架的规则集引擎。
[RuleSet(ContextA)]
public class RuleSet1
{
[Rule(TargetingA)]
public Conclusion Rule1(SubjectA subject)
{ Create conclusion }
[Rule(TargetingA)]
public Conclusion Rule2(SubjectA subject)
{ Create conclusion }
[Rule(TargetingB)]
public Conclusion Rule3(SubjectB subject)
{ Create conclusion }
}
[RuleSet(ContextB)]
public class RuleSet2
{
[Rule(TargetingB)]
public Conclusion Rule1(SubjectB subject)
{ Create conclusion }
[Rule(TargetingA)]
public Conclusion Rule2(SubjectA subject)
{ Create conclusion }
[Rule(TargetingB)]
public Conclusion Rule3(SubjectB subject)
{ Create conclusion }
}
public class Conclusion()
{
// Errorcode, Description and such
}
// contexts and targeting info are enums.
目标是创建一个可扩展的规则集,该规则集不会改变消费者POV中的API,同时在代码文件中具有良好的关注点分离。再次:像单元测试框架。
我正在尝试创建一个公开以下API的库
public static class RuleEngine
{
public static IEnumerable<IRuleSet> RuleSets(contextFlags contexts)
{
{
return from type in Assembly.GetExecutingAssembly().GetTypes()
let attribute =
type.GetCustomAttributes(typeof (RuleSetAttribute), true)
.OfType<RuleSetAttribute>()
.FirstOrDefault()
where attribute != null
select ?? I don't know how to convert the individual methods to Func's.
}
}
}
internal interface IRuleset
{
IEnumerable<Func<SubjectA, Conclusion>> SubjectARules { get; }
IEnumerable<Func<SubjectB, Conclusion>> SubjectBRules { get; }
}
...允许消费者像这样简单地使用(在本例中使用foreach代替LINQ以便于阅读)
foreach (var ruleset in RuleEgine.RuleSets(context))
{
foreach (var rule in ruleset.SubjectARules)
{
var conclusion = rule(myContextA);
//handle the conclusion
}
}
此外,如果你能告诉我如何摆脱“TargetingA”和“TargetingB”作为RuleAttribute参数,而是使用反射直接检查装饰方法的参数类型,将会非常有帮助。一直保持相同的简单外部API。
答案 0 :(得分:1)
您可以使用Delegate.CreateDelegate
和GetParameters
方法执行您想要的操作。
public class RuleSet : IRuleSet
{
public IEnumerable<Func<SubjectA, Conclusion>> SubjectARules { get; set; }
public IEnumerable<Func<SubjectB, Conclusion>> SubjectBRules { get; set; }
}
public static class RuleEngine
{
public static IEnumerable<IRuleSet> RuleSets() // removed contexts parameter for brevity
{
var result = from t in Assembly.GetExecutingAssembly().GetTypes()
where t.GetCustomAttributes(typeof(RuleSetAttribute), true).Any()
let m = t.GetMethods().Where(m => m.GetCustomAttributes(typeof(RuleAttribute)).Any()).ToArray()
select new RuleSet
{
SubjectARules = CreateFuncs<SubjectA>(m).ToList(),
SubjectBRules = CreateFuncs<SubjectB>(m).ToList()
};
return result;
}
}
// no error checking for brevity
// TODO: use better variable names
public static IEnumerable<Func<T, Conclusion>> CreateFuncs<T>(MethodInfo[] m)
{
return from x in m
where x.GetParameters()[0].ParameterType == typeof(T)
select (Func<T, Conclusion>)Delegate.CreateDelegate(typeof(Func<T, Conclusion>), null, x);
}
然后你可以像这样使用它:
var sa = new SubjectA();
foreach (var ruleset in RuleEngine.RuleSets())
{
foreach (var rule in ruleset.SubjectARules)
{
var conclusion = rule(sa);
// do something with conclusion
}
}
答案 1 :(得分:0)
在您的LINQ查询中,您直接前往RuleSetAttribute
,因此丢失了其他信息。如果您在多行代码中断查询,则可以使用GetMethods()
从类型中获取方法,然后您可以调用GetCustomAttribute<RuleAttribute>()
。