C# Interface Implementation Question

[Soon]

Hi,

I am new to C# and have a question regarding interface implementation in C#. In the COM days, we can have multiple COM objects implementing the same interface and instantiating one of them depending on the business requirements. For instance:

public function GetSavingAccountBalance(str_AcctNo as string, int_BankID as Integer) as double

Dim objSavingAcct as IBankAccount

if ( ID_BANK_1 = int_BankID ) then

set objSavingAcct = CreateObject ("Bank1.SavingAccount.1")

elseif ( ID_BANK_2 = int_BankID ) then

set objSavingAcct = CreateObject ("Bank2.SavingAccount.1")

end if

GetSavingAccountBalance = objSavingAcct.Balance( str_AcctNo )

set objSavingAcct = nothing

End Sub

In this case, both Bank1.SavingAccount.1 and Bank2.SavingAccount.1 are ProgIDs for 2 COM objects, and they both implement IBankAccount interface. If there are changes in the business logic, all I need to do is to instantiate another object with a different ProgID (which can be retrieved from a configuration file). This way I do not have to recompile the client again and makes the architecture very flexible.

How do I do this in C#? Any help will be appreciated. Thanks in advance.

Cheers,
Soon

[Ignacio Machin]

Hi,

You could define an interface, then have several classes to implement it, doing this you will get the same functionality.
But you can go a step further, though. You can declare in the app configuration file the class to be instantiate and the dll location and at runtime you can use it instead of using a multiple if construction ( in this way you do not have to hard code the different possibilities) , take a look at the code below:

Assembly ass = Assembly.LoadFile( Config.DataTransformatorLocation);

dataStrategic = (BaseTransformation) ass.CreateInstance( Config.DataTransformatorFQN);

Here I load an assembly and then instantiate a class declare in it that I know implement a defined interface. Config is a class that provide static properties to access configuration settings, DataTransformatorLocation return the path of the dll and DataTransformatorFQN return the Fully qualified name of the type.

Hope this help,
--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation
"Soon" <ys*******@yahoo.com> wrote in message news:%2****************@TK2MSFTNGP10.phx.gbl...
Hi,

I am new to C# and have a question regarding interface implementation in C#. In the COM days, we can have multiple COM objects implementing the same interface and instantiating one of them depending on the business requirements. For instance:

public function GetSavingAccountBalance(str_AcctNo as string, int_BankID as Integer) as double

Dim objSavingAcct as IBankAccount

if ( ID_BANK_1 = int_BankID ) then

set objSavingAcct = CreateObject ("Bank1.SavingAccount.1")

elseif ( ID_BANK_2 = int_BankID ) then

set objSavingAcct = CreateObject ("Bank2.SavingAccount.1")

end if

GetSavingAccountBalance = objSavingAcct.Balance( str_AcctNo )

set objSavingAcct = nothing

End Sub

In this case, both Bank1.SavingAccount.1 and Bank2.SavingAccount.1 are ProgIDs for 2 COM objects, and they both implement IBankAccount interface. If there are changes in the business logic, all I need to do is to instantiate another object with a different ProgID (which can be retrieved from a configuration file). This way I do not have to recompile the client again and makes the architecture very flexible.

How do I do this in C#? Any help will be appreciated. Thanks in advance.

Cheers,
Soon