Re: Array Marshalling different between VB6 & Script to an interop C#

I think you need to be declaring a Variant which contains an array or
strings, as opposed to an array of strings.

The scripts require all data types to be Variants.

Tom

KirkViehland wrote:
I have a very simple C# library that demonstrates a problem that I am trying
to figure out right now. I could post a full example, if this forum allowed
posting attachments.

Anyway, like I said, I have a very simple C# class...

namespace ScriptMarshalTester
{
using System;
using System.Reflection;
using System.Runtime.InteropServices;

[ComVisible(true)]
[Guid("AD07359C-D5D6-4A22-89D7-7DA80D3C4973")]
[ProgId("ScriptMarshalTester.StringTester")]
[ClassInterface(ClassInterfaceType.None)]
public class StringTester
: ScriptMarshalTester.IStringTester
{
public StringTester(){}

public void TestString
(
[In, MarshalAs(UnmanagedType.BStr)]
string value
)
{
Console.WriteLine( "\r\n" + MethodInfo.GetCurrentMethod().Name +
"\r\n" );
Console.WriteLine( new String('-',20) );
Console.WriteLine( "value=" + value );
}

public void TestStringArray
(
[MarshalAs(UnmanagedType.SafeArray,
SafeArraySubType=VarEnum.VT_BSTR)]
ref string[] values
)
{
Console.WriteLine( "\r\n" + MethodInfo.GetCurrentMethod().Name +
"\r\n" );
Console.WriteLine( new String('-',20) );

for ( int i = 0; i < values.Length; i++ )
Console.WriteLine( "values[" + i.ToString() + "]=" +
values[i]);
}

public void TestStringAndStringArray
(
[In, MarshalAs(UnmanagedType.BStr)]
string value,

[In, Out, MarshalAs(UnmanagedType.SafeArray,
SafeArraySubType=VarEnum.VT_BSTR)]
ref string[] values
)
{
Console.WriteLine( "\r\n" + MethodInfo.GetCurrentMethod().Name +
"\r\n" );
Console.WriteLine( new String('-',20) );

Console.WriteLine( "value=" + value );

for ( int i = 0; i < values.Length; i++ )
Console.WriteLine( "values[" + i.ToString() + "]=" +
values[i]);
}
}
}

And its interface definition is as follows...

namespace ScriptMarshalTester
{
using System;
using System.Runtime.InteropServices;

[ComVisible(true)]
[Guid("10F83921-A0EA-4270-8574-5D7577EB72EA")]
[InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]
public interface IStringTester
{
[DispId(1)]
void TestString
(
[In, MarshalAs(UnmanagedType.BStr)]
string value
);

[DispId(2)]
void TestStringArray
(
[In, MarshalAs(UnmanagedType.SafeArray,
SafeArraySubType=VarEnum.VT_BSTR)]
ref string[] values
);

[DispId(3)]
void TestStringAndStringArray
(
[In, MarshalAs(UnmanagedType.BStr)]
string value,

[In, MarshalAs(UnmanagedType.SafeArray,
SafeArraySubType=VarEnum.VT_BSTR)]
ref string[] values
);
}
}

Now, if I compile this and try to execute it with the following VB6 code
everything works as expected, ** Meaning no exceptions are thrown **. Here is
some sample VB6 code. You will notice in this snippet that the original
library has been compiled and registered with COM as ScriptMarshalTester. The
ProgId for the class that we will be interacting with is
ScriptMarshalTester.StringTester. Here is the VB6 subroutine...

Private Sub TestStrings()
Dim tester As ScriptMarshalTester.StringTester
Dim testValue As String
Dim testValues() As String

ReDim testValues(1)

Set tester = New ScriptMarshalTester.StringTester

testValue = "Hello World"
testValues(0) = "Hello"
testValues(1) = "World"

Call tester.TestString(testValue)
Call tester.TestStringArray(testValues())
Call tester.TestStringAndStringArray(testValue, testValues())
End Sub

At this point, everything behaves as expected. Once we introduce the script
client into the mix things start to take a quick downhill. I have 2 script
clients which both exhibit the same behavior, a VBScript client and a JScript
client. Here is the same method as the TestStrings method above in VBScript...

private sub TestStrings()

dim tester
dim testValue
dim testValues()

ReDim testValues(1)

set tester = WSCript.CreateObject("ScriptMarshalTester.StringTester")
testValue = "Hello World"
testValues(0) = "Hello"
testValues(1) = "World"

call tester.TestString(testValue)
call tester.TestStringArray(testValues)
call tester.TestStringAndStringArray(testValue,testValues)

end sub

And also in the following JScript...

function testStrings()
{
var tester = new ActiveXObject("ScriptMarshalTester.StringTester");

var testValue = new String("Hello World");
var testValues = new Array();

testValues[0] = "Hello";
testValues[1] = "World";

try
{
tester.TestString(testValue);
tester.TestStringArray
(
CreateSafeArray(testValues)
);
tester.TestStringAndStringArray
(
testValue,
CreateSafeArray(testValues)
);
}
catch(e)
{
WScript.StdOut.WriteLine(e);
WScript.StdOut.WriteLine(e.number & 0xFFFF);
WScript.StdOut.WriteLine(e.description);
}
}

// Converts a JScript Array to a SAFEARRAY
function CreateSafeArray( jsArray )
{
var dictionary = new ActiveXObject("Scripting.Dictionary");

for ( var i = 0; i < jsArray.length; i++ )
dictionary.add( i, jsArray[i] );

return(new VBArray(dictionary.Items()));
}

The problem surfaces in that the tester.TestStringArray method gets an
"Invalid procedure call or argument" while trying to pass the array of
strings to the TestStringArray method. Likewise, if the same script is coded
in JScript and the argument is converted to a SAFEARRAY the executing script
gets an "Invalid Procedure call or argument" while trying to marshall the
array parameter to the managed code.

Unless I have missed something in the documentation, I think that I have
declared these interfaces correctly. I know that it is something very simple,
but I can't seem to make this work. One requirement however is that the same
.Net component should be useable from both VB6 as well as script components.

Any help would be appreciated.

Thanks,
Kirk A. Viehland

.

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