C# 4.0: casting dynamic to static
- by Kevin Won
This is an offshoot question that's related to another I asked here. I'm splitting it off because it's really a sub-question:
I'm having difficulties casting an object of type dynamic to another (known) static type.
I have an ironPython script that is doing this:
import clr
clr.AddReference("System")
from System import *
def GetBclUri():
return Uri("http://google.com")
note that it's simply newing up a BCL System.Uri type and returning it. So I know the static type of the returned object.
now over in C# land, I'm newing up the script hosting stuff and calling this getter to return the Uri object:
dynamic uri = scriptEngine.GetBclUri();
System.Uri u = uri as System.Uri; // casts the dynamic to static fine
Works no problem. I now can use the strongly typed Uri object as if it was originally instantiated statically.
however....
Now I want to define my own C# class that will be newed up in dynamic-land just like I did with the Uri. My simple C# class:
namespace Entity
{
public class TestPy // stupid simple test class of my own
{
public string DoSomething(string something)
{
return something;
}
}
}
Now in Python, new up an object of this type and return it:
sys.path.append(r'C:..path here...')
clr.AddReferenceToFile("entity.dll")
import Entity.TestPy
def GetTest():
return Entity.TestPy(); // the C# class
then in C# call the getter:
dynamic test = scriptEngine.GetTest();
Entity.TestPy t = test as Entity.TestPy; // t==null!!!
here, the cast does not work. Note that the 'test' object (dynamic) is valid--I can call the DoSomething()--it just won't cast to the known static type
string s = test.DoSomething("asdf"); // dynamic object works fine
so I'm perplexed. the BCL type System.Uri will cast from a dynamic type to the correct static one, but my own type won't. There's obviously something I'm not getting about this...
