[erlang-questions] Otp.NET: It would be nice to have seamless string support

Roessner, Silvester <>
Wed Apr 29 08:11:57 CEST 2009


Hi,

(sorry for the former incomplete e-mail - I hit enter by accident)

I think it would be usefull to have a real Otp.Erlang.List object
that combines Otp.Erlang.List and Otp.Erlang.String.

This object should have a constructor String(string S)
and a methode stringValue().


The reason why I think this is sensible:

I run into a problem while I tried to send Otp.Erlang.String 
with length > 64k from a OTP.Net node to a native Erlang node.
The Erlang node only received a cut string, not the full one.

The cause of this trouble is the strong adherence of OTP.Net 
to the external term format.

The Erlang node sends a list in an external term "STRING_EXT"
when the list length < 64k and all list entries are integers 
in the range 0..255

But it sends a list as an external term "LIST_EXT" otherwise.

OTP.Net has implemented Otp.Erlang.String but this is not a 
real Erlang type only an external term.

When I use OTP.Net to receive from or send strings to another 
node I have to manually distinguish between these two cases.


Receiver:
                    ....
                    try
                    {
                        Otp.Erlang.String S =
(Otp.Erlang.String)Tuple.elementAt(1);
                        Payload = S.stringValue();
                    }
                    catch (InvalidCastException)
                    {
                        Otp.Erlang.List List =
(Otp.Erlang.List)Tuple.elementAt(1);
                        Payload = stringValue(List);
                    }
                    ....


        private string stringValue(Otp.Erlang.List L)
        {
            System.Text.StringBuilder s = new
System.Text.StringBuilder();
            int _arity = L.Length;
            Otp.Erlang.Long E_Char;
						
			for (int i = 0; i < _arity; i++)
			{
                                E_Char =
(Otp.Erlang.Long)L.elementAt(i);
				s.Append(E_Char.charValue());
			}
						
			return s.ToString();
        }



Sender:

                    ....
                    Otp.Erlang.Object[] Message = new
Otp.Erlang.Object[2];
                    Message[0] = new Otp.Erlang.Int(L);

                    if (L < 65000) 
                    {
                        Message[1] = new Otp.Erlang.String(Payload);
                    }
                    else
                    {
                        Otp.Erlang.String Test = new
Otp.Erlang.String(Payload);
                        int LL = Test.stringValue().Length;
                        new Otp.Erlang.List(
                        Message[1] = toList(Payload);
                    }
                    
                    Box.send(Other, new Tuple(Message));
                    ....


        private Otp.Erlang.List toList(string S)
        {
            int _arity = S.Length;
            Otp.Erlang.Object[] Longs = new Otp.Erlang.Object[_arity];

            for (int i = 0; i < _arity; i++)
            {
                Longs[i] = new Otp.Erlang.Long(S[i]);
            }

            return new Otp.Erlang.List(Longs);
        }
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