I have an interface Collection that defines a few methods:

int size();
bool contains(Object foo);
bool equals(Object foo);
etc.

Now I have a class, AbstractCollection that almost implements the Collection interface:

class AbstractCollection : Collection {

//implement everything but equals()

}

Now, I run DMD, and get:

util.d(111): class AbstractCollection 1interface function Collection.equals is not implemented

Fair enough.  Off topic, is that 1 supposed to be there in the error message before 'interface'?

So, I change the class to be abstract:

abstract class AbstractCollection : Collection {...

Still no dice.  What I found with tinkering is that I either have to

1. add a 'bool equals(Object foo);' to the class

or

2. Not call the class abstract and add a:
  abstract bool equals(Object foo);

inside the body of the class.

Since I am doing source level Java translation, this is an issue for me to find out all the methods that I have not implemented and stub them out without implementation.  Shouldn't the 'abstract class Foo' tell the compiler that the contract is not going to be fulfilled?

Walter, is this a bug or intended behavior?

Thanks
Scott Sanders

stonecobra wrote:
> class AbstractCollection : Collection {
> 
> //implement everything but equals()
> 
> }
> 
> Now, I run DMD, and get:
> 
> util.d(111): class AbstractCollection 1interface function Collection.equals is not implemented
> 

How did DWT deal with this?  Does SWT have any abstract classes?

Scott

stonecobra wrote:
> I have an interface Collection that defines a few methods:
> 
> int size();
> bool contains(Object foo);
> bool equals(Object foo);
> etc.
> 
> Now I have a class, AbstractCollection that almost implements the Collection interface:
> 
> class AbstractCollection : Collection {
> 
> //implement everything but equals()
> 
> }
> 
> Now, I run DMD, and get:
> 
> util.d(111): class AbstractCollection 1interface function Collection.equals is not implemented
> 
What's even more confusing (to me) is if I add:

bool equals();

The compiler stops complaining.  Note the lack of a parameter there?

Can someone explain this to me?

Scott Sanders

This is not a bug. For a long answer your should look for the thread "Three notable problems with method name resolution."

What is happening here is the compiler will not accept the inherited function .equals(Object) as satisfying the Interface as Java does. So you have to add a stub function:
================================================================
    class AbstractCollection : Collection {
        bit equals( Object obj ) { return super(obj); }
================================================================



stonecobra wrote:

> I have an interface Collection that defines a few methods:
> 
> int size();
> bool contains(Object foo);
> bool equals(Object foo);
> etc.
> 
> Now I have a class, AbstractCollection that almost implements the Collection interface:
> 
> class AbstractCollection : Collection {
> 
> //implement everything but equals()
> 
> }
> 
> Now, I run DMD, and get:
> 
> util.d(111): class AbstractCollection 1interface function Collection.equals is not implemented
> 
> Fair enough.  Off topic, is that 1 supposed to be there in the error message before 'interface'?
> 
> So, I change the class to be abstract:
> 
> abstract class AbstractCollection : Collection {...
> 
> Still no dice.  What I found with tinkering is that I either have to
> 
> 1. add a 'bool equals(Object foo);' to the class
> 
> or
> 
> 2. Not call the class abstract and add a:
>   abstract bool equals(Object foo);
> 
> inside the body of the class.
> 
> Since I am doing source level Java translation, this is an issue for me to find out all the methods that I have not implemented and stub them out without implementation.  Shouldn't the 'abstract class Foo' tell the compiler that the contract is not going to be fulfilled?
> 
> Walter, is this a bug or intended behavior?
> 
> Thanks
> Scott Sanders