Override Default Constructor of Partial Class with Another Partial Class

Asked 2008-10-29T18:02:36.677

I don't think this is possible, but if is then I need it :)

I have a auto-generated proxy file from the wsdl.exe command line tool by Visual Studio 2008.

The proxy output is partial classes. I want to override the default constructor that is generated. I would rather not modify the code since it is auto-generated.

I tried making another partial class and redefining the default constructor, but that doesn't work. I then tried using the override and new keywords, but that doesn't work.

I know I could inherit from the partial class, but that would mean I'd have to change all of our source code to point to the new parent class. I would rather not have to do this.

Any ideas, work arounds, or hacks?

//Auto-generated class
namespace MyNamespace {
   public partial class MyWebService : System.Web.Services.Protocols.SoapHttpClientProtocol {
      public MyWebService() {
         string myString = "auto-generated constructor";
         //other code...
      }
   }
}

//Manually created class in order to override the default constructor
namespace MyNamespace {
   public partial class MyWebService : System.Web.Services.Protocols.SoapHttpClientProtocol {
      public override MyWebService() { //this doesn't work
         string myString = "overridden constructor";
         //other code...
      }
   }
}

Edit Report

3 Answers

This is not possible. Partial classes are essentially parts of the same class; no method can be defined twice or overridden, and that includes the constructor.

You could call a method in the constructor, and only implement it in the other part file.

answered 2008-10-29T18:08:00.987

Hmmm, I think one elegant solution would be the following:

//* AutogenCls.cs file
//* Let say the file is auto-generated ==> it will be overridden each time when
//* auto-generation will be triggered.
//*
//* Auto-generated class, let say via xsd.exe
//*
partial class AutogenCls
{
    public AutogenCls(...)
    {
    }
}



//* AutogenCls_Cunstomization.cs file
//* The file keeps customization code completely separated from 
//* auto-generated AutogenCls.cs file.
//*
partial class AutogenCls
{
    //* The following line ensures execution at the construction time
    MyCustomization m_MyCustomizationInstance = new MyCustomization ();

    //* The following inner&private implementation class implements customization.
    class MyCustomization
    {
        MyCustomization ()
        {
            //* IMPLEMENT HERE WHATEVER YOU WANT TO EXECUTE DURING CONSTRUCTION TIME
        }
    }
}

This approach has some drawbacks (as everything):

It is not clear when exactly will be executed the constructor of the MyCustomization inner class during whole construction procedure of the AutogenCls class.
If there will be necessary to implement IDiposable interface for the MyCustomization class to correctly handle disposing of unmanaged resources of the MyCustomization class, I don't know (yet) how to trigger the MyCustomization.Dispose() method without touching the AutogenCls.cs file ... (but as I told 'yet' :)

But this approach offers great separation from auto-generated code - whole customization is separated in different src code file.

enjoy :)

answered 2010-04-02T20:57:23.660

Sometimes you don't have access or it's not allowed to change the default constructor, for this reason you cannot have the default constructor to call any methods.

In this case you can create another constructor with a dummy parameter, and make this new constructor to call the default constructor using ": this()"

public SomeClass(int x) : this()
{
    //Your extra initialization here
}

And when you create a new instance of this class you just pass dummy parameter like this:

SomeClass objSomeClass = new SomeClass(0);

answered 2012-02-14T09:49:03.997

Override Default Constructor of Partial Class with Another Partial Class

3 Answers

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