CODEWITHSUNDEEP
c#genericsreflectioncasting
Sam
Sam

Reputation: 4339

How to dynamically call Cast<T>

I have a List<object> that I want to cast to a strongly typed array. The problem is that I don't know the list type at compile time, as it can be one of many objects.

Essentially if I have Type objectType = list[0].GetType() I want to be able to call list.Cast<objectType>().ToArray().

How can I do this? I tried using Reflection as follows:

Type listType = list[0].GetType();
MethodInfo castMethod = typeof(Enumerable).GetMethod("Cast", BindingFlags.Static | BindingFlags.Public);
castMethod = castMethod.MakeGenericMethod(new Type[] { listType });
castMethod.Invoke(null, new object[] { list});

The invocation returns a CastIterator which appears to have no public methods.

Upvotes: 2

Views: 129

Answers (1)

Reed Copsey
Reed Copsey

Reputation: 564891

You could use:

MethodInfo castMethod = typeof(Enumerable).GetMethod("Cast", BindingFlags.Static | BindingFlags.Public);
castMethod = castMethod.MakeGenericMethod(new Type[] { listType });
object castIterator = castMethod.Invoke(null, new object[] { list});
var toArrayMethod = typeof(Enumerable).GetMethod("ToArray", BindingFlags.Static | BindingFlags.Public);
toArrayMethod = toArrayMethod.MakeGenericMethod(new Type[] { listType });
object theArray = toArrayMethod.Invoke(null, new[] {castIterator});

At the end of this, theArray will be an array that's strongly typed.

Upvotes: 4

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