142 lines
4.9 KiB
Markdown
142 lines
4.9 KiB
Markdown
+++
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title = "dynamica"
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draft = false
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tags = [
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"code",
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"csharp",
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"dynamica"
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]
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date = "2014-11-05"
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+++
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# Dynamica
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Zie ook [code/csharp/reflectie]({{< relref "wiki/code/csharp/reflectie.md" >}})
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### Expression trees opbouwen
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##### Van een MethodInfo instantie naar een Func<>
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```csharp
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var instanceToMemoize = Activator.CreateInstance<TClassToMemoize>();
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foreach (var method in instanceToMemoize.GetType().GetMethods(BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance))
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{
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var parameters ###### method.GetParameters().Select(p > Expression.Constant("test"));
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var expr = Expression.Lambda(Expression.Call(Expression.Constant(instanceToMemoize), method, parameters)).Compile();
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_Delegates.Add(method.ToString(), expr);
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}
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```
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Argumenten stuk klopt nog niet. Refs:
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1. http://stackoverflow.com/questions/2933221/can-you-get-a-funct-or-similar-from-a-methodinfo-object
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2. http://stackoverflow.com/questions/11367830/how-to-find-full-name-of-calling-method-c-sharp
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##### Memoization
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Ook mogelijk via `Func<>` wrappers; zie
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1. http://www.jaylee.org/post/2013/04/18/Memoization-and-Immutable-data-in-CSharp-Part-1.aspx
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2. http://www.jaylee.org/post/2013/04/22/Immutable-Data-and-Memoization-in-CSharp-Part-2.aspx
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Dit is een extension die 2 type arguments aanvaard:
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```csharp
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public static Func<TArg1, TArg2, TResult> AsMemoized<TArg1, TArg2, TResult>(this Func<TArg1, TArg2, TResult> func)
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{
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var values = new Dictionary<MemoizedKey<TArg1, TArg2>, TResult>();
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return (arg1, arg2) => MemoizedValue(func, arg1, arg2, values);
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}
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public static Func<TArg, TResult> AsMemoized<TArg, TResult>(this Func<TArg, TResult> funcArg)
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{
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Func<TArg, object, TResult> func ###### (arg1, arg2) > funcArg(arg1);
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var values = new Dictionary<MemoizedKey<TArg, object>, TResult>();
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return (arg) => MemoizedValue(func, arg, null, values);
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}
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private static TResult MemoizedValue<TArg1, TArg2, TResult>(Func<TArg1, TArg2, TResult> func, TArg1 arg1, TArg2 arg2, Dictionary<MemoizedKey<TArg1, TArg2>, TResult> values)
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{
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TResult value;
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var memoizedKey = new MemoizedKey<TArg1, TArg2>(arg1, arg2);
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if (!values.TryGetValue(memoizedKey, out value))
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{
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value ###### values[memoizedKey] func(memoizedKey.Arg1, memoizedKey.Arg2);
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}
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return value;
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}
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private class MemoizedKey<TArg1, TArg2>
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{
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public MemoizedKey(TArg1 arg1, TArg2 arg2)
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{
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Arg1 = arg1;
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Arg2 = arg2;
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}
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public TArg1 Arg1 { get; private set; }
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public TArg2 Arg2 { get; private set; }
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public override bool Equals(object obj)
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{
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if (ReferenceEquals(null, obj)) return false;
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if (ReferenceEquals(this, obj)) return true;
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if (obj.GetType() != this.GetType()) return false;
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return Equals((MemoizedKey<TArg1, TArg2>)obj);
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}
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public override int GetHashCode()
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{
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unchecked
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{
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return (EqualityComparer<TArg1>.Default.GetHashCode(Arg1) * 397) ^ EqualityComparer<TArg2>.Default.GetHashCode(Arg2);
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}
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}
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private bool Equals(MemoizedKey<TArg1, TArg2> other)
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{
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return EqualityComparer<TArg1>.Default.Equals(Arg1, other.Arg1) && EqualityComparer<TArg2>.Default.Equals(Arg2, other.Arg2);
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}
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}
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```
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Equals is nodig voor de `Dictionary` (generated).
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### Aspect Oriented Programming
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**PostSharp**: [http:*www.postsharp.net](http:*www.postsharp.net)
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#### Transacties wiren
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Zie [code/csharp/persistence]({{< relref "wiki/code/csharp/persistence.md" >}})
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#### Aspects applyen op assembly level
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Q: Ik wil AOP toepassen voor alle klassen (& [publieke] methods) in een bepaald project (DLL)<br/><br/>
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A: Gebruik [Multicasting aspects](http://www.postsharp.net/aspects/multicasting).
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Bijvoorbeeld, om exceptions overal op te vangen, en dan door te delegeren, evt screenshot van de app te nemen:
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```csharp
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[assembly: ScenarioTests.ScenarioExceptionHandler]
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namespace ScenarioTests
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{
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[Serializable]
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[ScenarioExceptionHandler(AttributeExclude = true)]
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public class ScenarioExceptionHandler : OnMethodBoundaryAspect
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{
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public override void OnException(MethodExecutionArgs args)
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{
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WebDriverExceptionHandler.Handle(args.Exception);
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base.OnException(args);
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}
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}
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}
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```
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De eerste regel, `[assembly:]` is van belang, zie documentatie. Je kan ook verder filteren by visibility etc, zoals in [Spring AOP/AspectJ]({{< relref "wiki/code/java/dynamica/aspectj.md" >}}) de strings in XML gedfiniëerd zijn. |