Dynamically create a delegate signature - C# Discussion Boards

MicealG6-Sep-07 5:25

6-Sep-07 5:25

I didn't ask for your life story or even a slight insight into it, lol, but now that you have I must admit it does sound pretty depressing, you have my sympathy.

I'm sure your probably the "big cheese" when it comes to posting and congratulations on that I'm sure your mother is very proud.

Freedom is the right to say that 2+2=5 if this is so everything else will follow.

Re: Cash for Help!

J4amieC6-Sep-07 12:17

J4amieC

6-Sep-07 12:17

The votes speak for themselves kiddo.

---

How to get answers to your questions[^]

Web Service returning DateTime one hour out

funkymint6-Sep-07 1:08

funkymint

6-Sep-07 1:08

Hi,

I've built a web service with an ASPX page as a test harness. My web service has a method which gets a DateTime object from an external application and displays it correctly.

I have a console application which makes a call to the same web service. When it calls the same web method as the test harness, the DateTime object is one hour out.

Can anyone suggest what the problem might be? Is it something to do with summer time?

Thanks Smile | :)

Really simple question on Drop Down List Boxes

Infernojericho6-Sep-07 0:42

Infernojericho

6-Sep-07 0:42

Just a quick question...Have been trying to figure this out for the past 30 minutes but with no luck. Figured I'll just post in here for help.

How exactly do you get the contents of the item selected in the Drop Down List? Here's the code:

lblResult.Text = ddlBackgroundColor.SelectedItem.Text;

However I am getting a blank lblResult everytime. I am just baffled where did I miss. Grrr....

Anyway advice is greatly appreciated. Thank you.

Re: Really simple question on Drop Down List Boxes

Sandeep Akhare6-Sep-07 0:54

Sandeep Akhare

6-Sep-07 0:54

Where are you populating the Drop downlist ?
the items are static one or dynamically you are adding ?
try to debug the application

Thanks and Regards
Sandeep

If If you look at what you do not have in life, you don't have anything,
If you look at what you have in life, you have everything... "

Re: Really simple question on Drop Down List Boxes

Infernojericho6-Sep-07 1:03

Infernojericho

6-Sep-07 1:03

Hi, thanks for the reply.

I am not sure what does populating mean, but all I did was open a form, dragged the Drop Down List, Button, and Label to the form.

I added a few items to the DDL, via the "items" properties. They were all hard coded beforehand, so I would assume they are static.

I am just trying to get the label to show what was chosen by the click of the button.

Thanks

Re: Really simple question on Drop Down List Boxes

Sandeep Akhare6-Sep-07 1:25

Sandeep Akhare

6-Sep-07 1:25

ok try to debug(F5) your application by putting debug point where you have written the code ...... and see dropdown list contains all the values
Assuming that you know how to debug and the code that you have written is in button click event

Thanks and Regards
Sandeep

If If you look at what you do not have in life, you don't have anything,
If you look at what you have in life, you have everything... "

Dynamically create a delegate signature

Leonardo Pelisoli6-Sep-07 0:42

Leonardo Pelisoli

6-Sep-07 0:42

Hello,

I'm new to C#, so please bear with me if the question is obvious and/or stupid.

I have a C# (.NET Framework 2.0) application that needs to call functions in an unmanaged C/C++ DLL. The name of the DLL is unknown at compile time (so I can't use the DllImportAttribute directly). The solution I adopted uses the native LoadLibrary/GetProcAddress combination, as seen in the code snippet below.

using System;
using System.Runtime.InteropServices;

namespace Simple
{
    class DLLPlugin
    {        
        [DllImport("kernel32", EntryPoint = "LoadLibrary")]
        private static extern IntPtr LoadLibrary(string lpLibFileName);
        [DllImport("kernel32", EntryPoint = "GetProcAddress", SetLastError = true)]
        private static extern IntPtr GetProcAddress(IntPtr hModule, string lpProcName);
        [DllImport("kernel32", EntryPoint = "FreeLibrary", SetLastError = true)]
        private static extern bool FreeLibrary(IntPtr hModule);

        public delegate void VoidVoidDelegate();
        
        private VoidVoidDelegate RunDelegate;
        private IntPtr moduleRef;

        public DLLPlugin(string dllName)
        {
            moduleRef = LoadLibrary(dllName);
            IntPtr pfn = GetProcAddress(moduleRef, "Run");
            RunDelegate = (VoidVoidDelegate)
                Marshal.GetDelegateForFunctionPointer(pfn, typeof(VoidVoidDelegate));
        }

        ~DLLPlugin()
        {
            FreeLibrary(moduleRef);
        }

        public void Run()
        {
            RunDelegate();
        }
    }
}

In the code you'll see that I declared a delegate,

public delegate void VoidVoidDelegate();
private VoidVoidDelegate RunDelegate;

and then used it in the constructor to store the function I'm going to call in the DLL. In order to do that, I had to use the delegate type twice: once as a parameter for GetDelegateForFunctionPointer and then again to cast the return value.

Now, this example calls a function named Run that receives no arguments and returns nothing (void), as specified by the delegate signature.

Now, my problem is that I don't know this signature at compile time. Maybe the first time it runs, the Run function will receive two strings and return a bool. Or maybe it will receive a string, two bools, an int and return a double. Or maybe something else.

What I need is to supply the return and argument types, and then create at runtime the right kind of delegate to use. I would then use this delegate created at runtime to supply the correct signature to the GetDelegateForFunctionPointer method and to correctly cast the return value. Not to mention to call my function in the DLL, of course.

If someone has any suggestions, I'd greatly appreciate the help. Code examples as well to illustrate, since I'm not at all familiar with using Reflection.Emit (I'm assuming it's going to go that way?).

Re: Dynamically create a delegate signature

TJoe6-Sep-07 8:55

TJoe

6-Sep-07 8:55

The code below should do what you want, but I have not tested it. The core code comes from here[^].

<br />
AssemblyName assembly = new AssemblyName();<br />
assembly.Version = new Version(1, 0, 0, 0);<br />
assembly.Name = "ReflectionEmitDelegateTest";<br />
<br />
AssemblyBuilder assemblyBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(assembly,<br />
    AssemblyBuilderAccess.Run);<br />
<br />
ModuleBuilder modbuilder = assemblyBuilder.DefineDynamicModule("MyModule", true);<br />
<br />
TypeBuilder typeBuilder = modbuilder.DefineType("MyDelegateType",<br />
    TypeAttributes.Class | TypeAttributes.Public | TypeAttributes.Sealed |<br />
    TypeAttributes.AnsiClass | TypeAttributes.AutoClass,<br />
    typeof(MulticastDelegate));<br />
<br />
ConstructorBuilder constructorBuilder = typeBuilder.DefineConstructor(MethodAttributes.RTSpecialName |<br />
    MethodAttributes.HideBySig | MethodAttributes.Public,<br />
    CallingConventions.Standard,<br />
    new Type[] { typeof(object), typeof(System.IntPtr) });<br />
constructorBuilder.SetImplementationFlags(MethodImplAttributes.Runtime | MethodImplAttributes.Managed);<br />
<br />
// Build the parameters<br />
Type[] paramTypes = new Type[2];<br />
paramTypes[0] = typeof(Int32);<br />
paramTypes[1] = typeof(String);<br />
<br />
// Define the Invoke method for the delegate<br />
MethodBuilder methodBuilder = typeBuilder.DefineMethod("Invoke",<br />
    MethodAttributes.Public | MethodAttributes.HideBySig |<br />
    MethodAttributes.NewSlot | MethodAttributes.Virtual,<br />
    typeof(Int32),<br />
    paramTypes);<br />
methodBuilder.SetImplementationFlags(MethodImplAttributes.Runtime | MethodImplAttributes.Managed);<br />
<br />
// Get the type<br />
Type type = typeBuilder.CreateType();<br />
<br />
// Create an instance<br />
Delegate del = Marshal.GetDelegateForFunctionPointer(pfn, type);<br />
del.DynamicInvoke(1, "2");<br />

Take care,
Tom

-----------------------------------------------
Check out my blog at http://tjoe.wordpress.com

Re: Dynamically create a delegate signature

Leonardo Pelisoli6-Sep-07 22:23

Leonardo Pelisoli

6-Sep-07 22:23

It works! It's exactly what I needed. Thanks a lot for your help, I greatly appreciate it.

UPnP InvokeAction

MicealG6-Sep-07 0:27

MicealG

6-Sep-07 0:27

Help!

I have been using the dotNet Framework to create an UPnP Control Point application, this application makes use of the Microsoft UPNPLib.

The problem I have is when I "Invoke an Action", because the UPnP device that I am invoking the action on is building up a big response that could take a while to be received by my application the action keeps timing out (at around 36 seconds) is there anyway to extend the timeout period?

Freedom is the right to say that 2+2=5 if this is so everything else will follow.

compare MS Word Documents

Nitin.raj6-Sep-07 0:05

Nitin.raj

6-Sep-07 0:05

Hi,
I have to compare MS Word Documents ie., the original document is to be compared with the same document after some editing and the process should be able to show the changes made. Please help me. The code should be in C#

thanx,

Nitin.

Nitin Raj Bidkikar

Nitin Raj Bidkikar

Re: compare MS Word Documents

originSH6-Sep-07 0:08

originSH

6-Sep-07 0:08

You already posted this 12 minutes ago. Why repost so soon?

Re: compare MS Word Documents

Nitin.raj6-Sep-07 0:11

Nitin.raj

6-Sep-07 0:11

i made the question more clear...........your answer didnt help.....got any other solution

Nitin Raj Bidkikar

Re: compare MS Word Documents

originSH6-Sep-07 0:22

originSH

6-Sep-07 0:22

Well there are probably libraries around that you can buy that will do this. There possibly code around for free, have you even tried searching? When you post here you should have atleast had a look around for something.

Assuming that you had searched I was fairly sure there wasn't going to be any free libraries which leaves you with the option of making your own ... which is why I gave the reply I did.

Re: compare MS Word Documents

mav.northwind6-Sep-07 0:26

mav.northwind

6-Sep-07 0:26

You can change your question after posting it, if you think you didn't make yourself clear the first time... No need to create a new question everytime.

Here's an article about a Diff engine you could use:
http://www.codeproject.com/cs/algorithms/diffengine.asp[^]

Regards,
mav

--
Black holes are the places where God divided by 0...

Method to set time

iet20005-Sep-07 23:59

iet2000

5-Sep-07 23:59

Hi all,
I want to download a file for every one minute from ftp server to client in .net(c#).
I got all the remaining code to download the file but could not find the method to include this timespan.
Please suggest me at the earliest.

Priya

Re: Method to set time

Vikram A Punathambekar6-Sep-07 0:14

Vikram A Punathambekar

6-Sep-07 0:14

You will need a Timer control for this. There are lots of examples on Google.

Cheers,
विक्रम

Be yourself, no matter what they say.
- Sting, Englishman in New York.

Re: Method to set time

iet20006-Sep-07 1:19

iet2000

6-Sep-07 1:19

It worked.
Thanks and Regards,

Priya

Compare Word docs

Nitin.raj5-Sep-07 23:53

Nitin.raj

5-Sep-07 23:53

i have to compare a word document which has been edited with the original ie., document before editing. how do i do this in c#.

Nitin Raj Bidkikar

Re: Compare Word docs

originSH6-Sep-07 0:05

originSH

6-Sep-07 0:05

You haven't specified the version on word so I'm going to assume you don't mean 2007.

Older versions of word use Structured Storage aka DocFile.

These files are accessed via the windows api ... heres an article covering that api:

http://www.codeproject.com/file/structstor.asp[^]

There are lots of hits on google for using Strucutred Storage[^] and DocFile[^] from C#.

crystal report export problem

sakthi dasan5-Sep-07 23:38

sakthi dasan

5-Sep-07 23:38

Hi All

I am using crystal Report in C# 2005 asp.net
I want to export the crystal report to image (like Jpeg,Gif)
Any one please help me

it is very urgent Rose | [Rose]

Sakti

Licencing Problem urgent

Nishad855-Sep-07 23:34

Nishad85

5-Sep-07 23:34

I have an application in C# which should be installed on 10 machines.. I would like a way to make sure that they do not install on more than that. I would like to give them a way to activate each terminal. Since all terminals will be sharing a DataBase ,maybe we can have a verification process that asks them to input an activation code.Can any one help me regarding this?

Re: Licencing Problem urgent

MicealG6-Sep-07 1:27

MicealG

6-Sep-07 1:27

If you don't mind spending the money you can use www.copyminder.com but if I were you I would request the names of the 10 computers and their IP Addresses that the application will be running on this way you can check if a computer is one of these 10 and if so allow the application to run otherwise not.

I know it's messy and probably not the best idea, but it will work.

Freedom is the right to say that 2+2=5 if this is so everything else will follow.

String.IsNullOrEmpty

nasambur5-Sep-07 23:31

nasambur

5-Sep-07 23:31

Hi,
Which one gives better performance, checking a string against null & empty.

string s = "something";

for(int i=0; i<100; i++) {
  if(s != null) {
    if(s.Length > 0) {
      // do something
    }
  }
}

for(int i=0; i<100; i++) {
  if(!String.IsNullOrEmpty(s)) {
    // do something
  }
}

plz help,
nas

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