Type.GetMethod and ref Parameters in C#

[AxlsPixel]

Hi All,

I have a class (called CTestClass) within which I have a method
(Foo). This method has the following signature:

Foo(int x, int y, ref int z)

I am attempting to use reflection to invoke this method but before
doing that I want to use Type.GetMethod to bind to it and validate
it's signature. The problem is this binding fails due to the ref
parameter. I have tried using the ParameterModifi er structure. However
I ran across the following documentation in MSDN:

=============== =
Although the default binder does not process ParameterModifi er (the
modifiers parameter), you can use the abstract
System.Reflecti on.Binder class to write a custom binder that does
process modifiers. ParameterModifi er is only used when calling through
COM interop, and only parameters that are passed by reference are
handled.

The types array and the modifiers array have the same length. A
parameter specified in the types array can have the following
attributes, which are specified in the modifiers array: pdIn, pdOut,
pdLcid, pdRetval, pdOptional, and pdHasDefault, which represent [In],
[Out], [lcid], [retval], [optional], and a value specifying whether
the parameter has a default value. A parameter's associated attributes
are stored in the metadata and are used for interoperabilit y.

===============

With this in mind I have the following question,s:

1. Can the ParameterModifi er structure be used with non-COM i.e.
..NET class methods?

2. Does the default implementation of Type.GetMethod use this
structure? The documentation suggests writing a custom binder. Where
does that come into the picture?

3. If I can simply call Type.GetMethod without any having to
implement any other interface then how would I go about invoking
Type.GetMethod in the case of my function "Foo" specifically how do I
construct the ParameterModifi er array to pass as an argument?

4. Is there a simpler way to achieve this? (This probably should
have been #1 :))

Thanks,

Rudolph

[Mattias Sjögren]

> I have a class (called CTestClass) within which I have a method

(Foo). This method has the following signature:

Foo(int x, int y, ref int z)

I am attempting to use reflection to invoke this method but before
doing that I want to use Type.GetMethod to bind to it and validate
it's signature. The problem is this binding fails due to the ref
parameter.

The following should work for that signature

Type[] paramTypes = new Type[] {typeof(int), typeof(int),
Type.GetType("S ystem.Int32&")} ;
MethodInfo mi = typeof(CTestCla ss).GetMethod( "Foo", paramTypes );

I don't think ParameterModifi er will help you here.

Mattias

--
Mattias Sjögren [MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/
Please reply only to the newsgroup.

[AxlsPixel]

Thanks that worked like a charm. What is the purpose of the
ParameterModife r sturcture though (just out of curiosity)
Mattias Sjögren <ma************ ********@mvps.o rg> wrote in message news:<eK******* *******@tk2msft ngp13.phx.gbl>. ..

I have a class (called CTestClass) within which I have a method
(Foo). This method has the following signature:

Foo(int x, int y, ref int z)

I am attempting to use reflection to invoke this method but before
doing that I want to use Type.GetMethod to bind to it and validate
it's signature. The problem is this binding fails due to the ref
parameter.

The following should work for that signature

Type[] paramTypes = new Type[] {typeof(int), typeof(int),
Type.GetType("S ystem.Int32&")} ;
MethodInfo mi = typeof(CTestCla ss).GetMethod( "Foo", paramTypes );

I don't think ParameterModifi er will help you here.

Mattias

[Mattias Sjögren]

What is the purpose of the
ParameterModif er sturcture though (just out of curiosity)

You can use it to indicate marshaling direction (what you'd normally
do with the In and Out attributes) for a parameter in a late bound
call.

Mattias

--
Mattias Sjögren [MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/
Please reply only to the newsgroup.

[phancey]

this works fine for reference integers but I am trying to do reference
strings and the same technique does not work.

can you give me an idea for a solution?

i.e
public void fn6(string p_strData, ref string p_strData2)
{
p_strData2 = "test";
}

thanks
Phil

[Jon Skeet [C# MVP]]

<ph*****@2bytes .co.uk> wrote:

this works fine for reference integers but I am trying to do reference
strings and the same technique does not work.

can you give me an idea for a solution?

i.e
public void fn6(string p_strData, ref string p_strData2)
{
p_strData2 = "test";
}

What works fine? What are you trying to do, exactly?

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[phancey]

Trying to invoke a Web Service method dynamically which has a reference
parameter (in/out). If the reference parameter is an integer (as in
example fn4 above) I can get this to work, the parameter value is
changed by the web method. But if the reference parameter is a string
as in my fn6 example, the web method does not change the parameter.

So my parameter array consists of 2 string objects in this case. Now in
the integer case which works I do not need to set the type of parameter
to Int& to get it to be changed by the function, just assigning the
value 20 sets it to an integer and the fact that it is a reference
parameter in the Web method means that it gets changed. Why won't the
same thing work for my string and what is my alternative solution?
Thanks for any help.
Phil

[Jon Skeet [C# MVP]]

<ph*****@2bytes .co.uk> wrote:

Trying to invoke a Web Service method dynamically which has a reference
parameter (in/out). If the reference parameter is an integer (as in
example fn4 above)
There *is* no example function above, because you haven't quoted
anything.

It would help greatly if you'd quote what you're replying to.
I can get this to work, the parameter value is
changed by the web method. But if the reference parameter is a string
as in my fn6 example, the web method does not change the parameter.

Could you post a short but complete program which demonstrates the
problem?

See http://www.pobox.com/~skeet/csharp/complete.html for details of
what I mean by that.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[phancey]

sorry Jon, I guess you may not be seeing the whole thread. I was
referring to the example function as posted by SR on July 16 2003.

Anyway.

Using the example below, if I debug it and go into the DynWSLib
function InvokeCall, I can see that, just after the ...mi.Invoke... '
line, methodparams have not been changed.

However if I use
wsp.MethodName = "RefInt";
object paramValue = 20;

instead in my client code, the same debugging will show that
methodparams have changed from 20 to 4.

Here is my Web Service with it's web methods (minus standard Component
Designer generated code):

using System;
using System.Collecti ons;
using System.Componen tModel;
using System.Data;
using System.Diagnost ics;
using System.Web;
using System.Web.Serv ices;

namespace WebService1
{
[WebService(Name ="Phil's Service", Description="Te st Service
Application developed by Phil Hancey", Namespace="Land Sec")]

public class Service1 : System.Web.Serv ices.WebService
{
public Service1()
{
InitializeCompo nent();
}

[WebMethod]
public bool RefString(ref string Errmess)
{
Errmess = "error";
return true;
}
[WebMethod]
public bool RefInt(ref int Errmess)
{
Errmess = 4;
return true;
}
}
}

My client code is this:

using System;
using System.Collecti ons;
using System.Componen tModel;
using System.Drawing;
using System.IO;
using System.Reflecti on;
using System.Windows. Forms;
using AxSHDocVw;
using Thinktecture.To ols.Web.Service s.DynamicProxy;
using Thinktecture.To ols.Web.Service s.Extensions;

namespace Thinktecture.To ols.Web.Service s.TestClient
{
public class TesterForm : Form
{

private DynamicWebServi ceProxy wsp = null;
private Container components = null;

public TesterForm()
{
InitializeCompo nent();
wsp = new DynamicWebServi ceProxy();
}

protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Disp ose();
}
}
base.Dispose( disposing );
}

[STAThread]
static void Main()
{
Application.Run (new TesterForm());
}

private void Form1_Load(obje ct sender, EventArgs e)
{
this.Cursor = Cursors.WaitCur sor;
try
{
wsp.EnableMessa geAccess = true;
wsp.Wsdl = "http://localhost/WebService1/Service1.asmx?w sdl";
wsp.TypeName = "PhilsServi ce";
wsp.Url = new Uri("http://localhost/WebService1/Service1.asmx") ;
wsp.MethodName = "RefString" ;
object paramValue = "start";
wsp.AddParamete r(paramValue);
object result = wsp.InvokeCall( );
}
catch(Exception ex)
{
MessageBox.Show (ex.Message);
}
this.Cursor = Cursors.Default ;
}
}
}

I am using the DynWSLib version 1.5 downloaded from
http://www.thinktecture.com/Resource...b/default.html
which is a bit big to copy here but it basically creates a proxy of the
web service using Reflection. Let me know if you want me to post all
their code too.
thanks for your continued interest despite my obvious naivety!

Phil

[Jon Skeet [C# MVP]]

<ph*****@2bytes .co.uk> wrote:

sorry Jon, I guess you may not be seeing the whole thread. I was
referring to the example function as posted by SR on July 16 2003.
And unsurprisingly, servers don't always carry posts from 18 months ago
:)

<snip>
I am using the DynWSLib version 1.5 downloaded from
http://www.thinktecture.com/Resource...b/default.html
which is a bit big to copy here but it basically creates a proxy of the
web service using Reflection. Let me know if you want me to post all
their code too.

It's quite possible the problem is in DynWSLib, of course :(

I'll try to have a look, but I'm afraid I won't have any time until
next week as I'm going away for the weekend. I may be able to test it
on Monday night.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too