[英]How to activate a generic method that takes an action as its parameter
當只能在運行時推斷類型時,您將如何使用反射來執行以下方法?
MainObject.TheMethod<T>(Action<OtherObject<T>>)
在日常使用中,通常:
mainObject.Method<Message>(m => m.Do("Something"))
因此,給定一個類型列表,我需要在上面的方法中將它們替換為T並調用。
這是我在變成膩子之前得到的地方:
var mapped = typeof(Action<OtherObject<>>).MakeGenericType(t.GetType());
Activator.CreateInstance(mapped, new object[] { erm do something?});
typeof(OtherObject)
.GetMethod("TheMethod")
.MakeGenericMethod(t.GetType())
.Invoke(model, new object[] { new mapped(m => m.Do("Something")) });
更新:為了澄清,我有一個類型列表,我希望為每個類型執行相同的已知方法。 偽代碼:
foreach(var t in types)
{
mainObject.TheMethod<t>(mo => mo.Do("Something"))
}
(TheMethod()的參數類型是Action<OtherObject<T>>
,如上所述)
FluentNHibernate.Automapping.AutoPersistenceModel Override<T>(System.Action<AutoMapping<T>> populateMap)
動作與AutoMapping<T>.Where("something")
相同。在AutoMapping<T>.Where("something")
model.Override<Message>(m => m.Where("DeletedById is null"))
現在,為一堆類型做到這一點:)
您可以使用表達式解決此問題:
foreach(var t in types)
{
var mapped = typeof(AutoMapping<>).MakeGenericType(t);
var p = Expression.Parameter(mapped, "m");
var expression = Expression.Lambda(Expression.GetActionType(mapped),
Expression.Call(p, mapped.GetMethod("Do"),
Expression.Constant("Something")), p);
typeof(SomeOtherObject).GetMethod("TheMethod").MakeGenericMethod(t)
.Invoke(model, new object[] { expression.Compile() });
}
更新:完整的工作示例(粘貼到LINQPad並運行它):
void Main()
{
var types = new []{typeof(string), typeof(Guid)};
SomeOtherObject model = new SomeOtherObject();
foreach(var t in types)
{
var mapped = typeof(AutoMapping<>).MakeGenericType(t);
var p = Expression.Parameter(mapped, "m");
var expression = Expression.Lambda(
Expression.GetActionType(mapped),
Expression.Call(p, mapped.GetMethod("Do"),
Expression.Constant("Something")), p);
typeof(SomeOtherObject).GetMethod("TheMethod")
.MakeGenericMethod(t)
.Invoke(model,
new object[] { expression.Compile() });
}
}
class AutoMapping<T>
{
public void Do(string p)
{
Console.WriteLine(typeof(T).ToString());
Console.WriteLine(p);
}
}
class SomeOtherObject
{
public void TheMethod<T>(Action<AutoMapping<T>> action)
{
var x = new AutoMapping<T>();
action(x);
}
}
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