Dynamic invocation and interfaces

  • Thread starter Thread starter Chakravarthy Bollapalli \(IFIN SCC AI\)
  • Start date Start date
C

Chakravarthy Bollapalli \(IFIN SCC AI\)

Hi,
I have a .net dll (say dll assembly) which has a class implimenting an
interface defined in a application (say application assembly)
so I add the reference of the application assembly to the dll project and
compile. I have a dll available.

from the application assembly i create an instance of the class defined in
dll assembly.

When i try to typecast the instance into an interface instance I get an
exception
--
An unhandled exception of type 'System.InvalidCastException' occurred in
test.exe

Additional information: Specified cast is not valid.
--

but I am able to invoke methods on the instance using
Type.InvokeMember(......) method.

what could be wrong?

kalyan
 
Hi,

I'd declare the interface in the DLL instead. Referencing the application
assembly from a DLL is definitely not a good idea and it should be avoided.

--
Sincerely,
Dmitriy Lapshin [C# / .NET MVP]
Bring the power of unit testing to the VS .NET IDE today!
http://www.x-unity.net/teststudio.aspx

"Chakravarthy Bollapalli (IFIN SCC AI)"
 
Hi,
May be its not a good idea to declare it in the application assembly but
my requirement is that I declare it in application assembly.
Infact there is one such example in oreilly's "Programming Visual C#
..NET 2003" chapter 18.

I am not sure what I am missing some compilation option or did visual
studio screw it up.

Anticipating a response

regards
kalyan


Dmitriy Lapshin said:
Hi,

I'd declare the interface in the DLL instead. Referencing the application
assembly from a DLL is definitely not a good idea and it should be avoided.

--
Sincerely,
Dmitriy Lapshin [C# / .NET MVP]
Bring the power of unit testing to the VS .NET IDE today!
http://www.x-unity.net/teststudio.aspx

"Chakravarthy Bollapalli (IFIN SCC AI)"
Hi,
I have a .net dll (say dll assembly) which has a class implimenting an
interface defined in a application (say application assembly)
so I add the reference of the application assembly to the dll project and
compile. I have a dll available.

from the application assembly i create an instance of the class defined in
dll assembly.

When i try to typecast the instance into an interface instance I get an
exception
--
An unhandled exception of type 'System.InvalidCastException' occurred in
test.exe

Additional information: Specified cast is not valid.
--

but I am able to invoke methods on the instance using
Type.InvokeMember(......) method.

what could be wrong?

kalyan
Click to expand...
Click to expand...
 
When there is no relationship between types, you are not allowed to
typecast.

Try declaring the interface elsewhere and not in the application dll.

with regards,


J.V.Ravichandran
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qry=Ravichandran+J.V.&cob=aspnetpro
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