Converting an integer to a boxed enum type only known at runtime
Posted
by Marc Gravell
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Published on 2010-04-17T21:47:35Z
Indexed on
2010/04/17
21:53 UTC
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Imagine we have an enum:
enum Foo { A=1,B=2,C=3 }
If the type is known at compile-time, a direct cast can be used to change between the enum-type and the underlying type (usually int
):
static int GetValue() { return 2; }
...
Foo foo = (Foo)GetValue(); // becomes Foo.B
And boxing this gives a box of type Foo
:
object o1 = foo;
Console.WriteLine(o1.GetType().Name); // writes Foo
(and indeed, you can box as Foo
and unbox as int
, or box as int
and unbox as Foo
quite happily)
However (the problem); if the enum type is only known at runtime things are... trickier. It is obviously trivial to box it as an int
- but can I box it as Foo
? (Ideally without using generics and MakeGenericMethod
, which would be ugly). Convert.ChangeType
throws an exception. ToString
and Enum.Parse
works, but is horribly inefficient.
I could look at the defined values (Enum.GetValues
or Type.GetFields
), but that is very hard for [Flags]
, and even without would require getting back to the underlying-type first (which isn't as hard, thankfully).
But; is there a more direct to get from a value of the correct underlying-type to a box of the enum-type, where the type is only known at runtime?
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