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Body-less method declaration

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Join Date: Oct 2009

Posts: 3

Reputation: serban is an unknown quantity at this point

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serban

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Newbie Poster

Body-less method declaration

Oct 23rd, 2009

Hello

I have seen the following method syntax and I am trying to understand how this works/or doesn't:

public class MyClass
{

public MyClass();

public MyClass(string param);
}

There is no implementation of the methods (constructors) and class is not declared virtual either...
Is this something new in C# 3.0 ???

Any ideas???

Thank you

•

Join Date: Feb 2009

Posts: 3,210

Reputation: sknake has much to be proud of

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sknake

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.NET Enthusiast

Oct 23rd, 2009

That doesn't compile in 3.5 and I think the error message answers your question:

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text Syntax (Toggle Plain Text)

'daniweb.MyClass.MyClass()' must declare a body because it is not marked abstract, extern, or partial
'daniweb.MyClass.MyClass(string)' must declare a body because it is not marked abstract, extern, or partial

Interfaces allow you to declare methods similarly but the method must have a return type:

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 C# Syntax (Toggle Plain Text) 
  public interface ITest
  {
    void ITest();
  }
  public interface ITest
  {
    void ITest();
  }

I suspect you were looking at partial class definitions.

Scott Knake
Custom Software Development
Apex Software, Inc.

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Join Date: Jun 2005

Posts: 2,039

Reputation: Rashakil Fol is just really nice

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Rashakil Fol Rashakil Fol is offline

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-1

Oct 23rd, 2009

Either that or the methods were abstract.

All my posts may be redistributed under the GNU Free Documentation License.

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Join Date: Feb 2009

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sknake

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Oct 23rd, 2009

•

Originally Posted by Rashakil Fol

Either that or the methods were abstract.

You can't have abstract constructors since the child classes cannot implement constructors from an inherited class...

None of these are valid:

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 C# Syntax (Toggle Plain Text) 
  public abstract class AbstractClass
  {
    abstract AbstractClass();
  }
  public abstract class AbstractClass2
  {
    AbstractClass2();
  }
  public class AbstractClass3
  {
    abstract AbstractClass3();
  }
  public abstract class AbstractClass
  {
    abstract AbstractClass();
  }
  public abstract class AbstractClass2
  {
    AbstractClass2();
  }
  public class AbstractClass3
  {
    abstract AbstractClass3();
  }

Scott Knake
Custom Software Development
Apex Software, Inc.

•

Join Date: Jun 2005

Posts: 2,039

Reputation: Rashakil Fol is just really nice

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Rashakil Fol Rashakil Fol is offline

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Oct 23rd, 2009

•

Originally Posted by sknake

You can't have abstract constructors since the child classes cannot implement constructors from an inherited class...

Obviously I wasn't talking about his code example because the methods there were not marked abstract.

All my posts may be redistributed under the GNU Free Documentation License.

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DdoubleD

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Note to self: why is this title field here?

Oct 24th, 2009

•

Originally Posted by serban

Hello

I have seen the following method syntax and I am trying to understand how this works/or doesn't:

public class MyClass
{

public MyClass();

public MyClass(string param);
}

There is no implementation of the methods (constructors) and class is not declared virtual either...
Is this something new in C# 3.0 ???

Any ideas???

Thank you

Perhaps you saw some C++ code that looks like this, which in its simplest form, is very similar in appearance. In C++, this is called forward declaration. C# does not allow forward declarations.