perhaps a bug in pather.cs

[OrNot]

In current 3.0.0 version, it seems that null object can not be returned from peer endpoints. If not intentionally, this seems a bug.

public override void patch(Ice.Object v)
{
Debug.Assert(type_ != null);

if (v!=null) // necessary?
{
if(!type_.IsInstanceOfType(v))
{
throw new System.InvalidCastException("expected element of type " + type()
+ " but received " + v.GetType().FullName);
}
}

value = v;

}


Best regards
OrNot

[michi]

I'm not sure I understand why this might cause a problem. Do you have test case to show where this would cause incorrect behavior?

Cheers,

Michi.

[OrNot]

hi, Michi,
It is easy to reproduce this error if you add ,say, HelloI ,in server ,

public class HelloI: Demo.helloDisp_
{
public override Demo.TestClass get(Ice.Current current__)

{
return null;
}


};

That is, return a null reference to a object.



Here are the original codes:

public override void patch(Ice.Object v)
{
Debug.Assert(type_ != null);
if(!type_.IsInstanceOfType(v))
{
throw new System.InvalidCastException("expected element of type " + type()
+ " but received " + v.GetType().FullName);
}

value = v;

}

When v is undefined, an exception is thrown.

[michi]

Thanks for that, I'll have a look at this next week.

Cheers,

Michi.

[michi]

Thanks muchly for the bug report! I've posted a patch here.

Cheers,

Michi.

[OrNot]

Considering the fellowing slice definition:

// ************************************************** ********************
//
// Copyright (c) 2003-2005 ZeroC, Inc. All rights reserved.
//
// This copy of Ice is licensed to you under the terms described in the
// ICE_LICENSE file included in this distribution.
//
// ************************************************** ********************

#ifndef HELLO_ICE
#define HELLO_ICE
module Demo
{
class Node;
["clr:collection"]sequence<Node> NodeList;

class Node
{
NodeList subNode;
};
interface Hello
{
nonmutating void sayHello();
Node getNode();
};

};
#endif


In the HelloI (say,Java sample codes):

public class HelloI extends _HelloDisp
{
public void
sayHello(Ice.Current current)
{
System.out.println("Hello World!");
}

public Node getNode(Current __current)
{
Node fatherNode = new Node();
Node[] subNodes = new Node[2];
fatherNode.subNode = subNodes;
return fatherNode;
}
}


That's, return some objects with null in a sequence.;


This can result in an exception from Patcher.cs in client when the v==null,


public override void patch(Ice.Object v)
{
try
{
if(_seq is IList)
{
if(_index >= _seq.Count)
{
for(int i = _seq.Count; i <= _index; i++)
{
((IList)_seq).Add(dummyObject); // IList implementation does not permit adding null :-(
}
}

////////////////////////Exception from here////////////////////////////////
/// ((IList)_seq)[_index] = v;
////////////////////////////////////////////////////////


}
else
{
((System.Array)_seq).SetValue(v, _index);
}
}
catch(System.Exception)
{
throw new System.InvalidCastException("expected element of type " + type()
+ " but received " + v.GetType().FullName);
}
}


I am not very sure about this bug and maybe it is my useage mistake.


OS: win2000;
Vistual Studio 2003;
Ice: 3.0.0;




Cheers
OrNot

[michi]

Thanks for the bug report.

The problem is caused by the IList methods of CollectionBase. Unfortunately, it does not permit null to be inserted into a list (God only knows why... ) and, to make things worse, the Add method and the indexer of the implementation of CollectionBase appear to be non-virtual, so the call isn't dispatched into the NodeList implementation

I'm still investigating possible workarounds.

Michi.

[michi]

I've posted a patch for this problem. Thanks for reporting this!

Cheers,

Michi.