Use dll dynamically in code.

  • Thread starter Thread starter Mr. X.
  • Start date Start date
How can I use dll dynamically in my code?
Click to expand...

I assume the DLL is a .NET assembly.

The simplest variant must be:

Isomeinterface o =
(Isomeinterface)Assembly.Load(dllname).CreateInstance(classname);

Arne
 
Assuming that by "dynamically" you mean that you don't want to link your
own assembly to the DLL assembly you want to use (i.e. use a DLL not
known at compile time), then the basic approach involves reflection.

There is a new plug-in framework with .NET 4.0 that is supposed to make
this easier. If you can restrict your goal to something where that is
usable, then that would probably be a better approach.
Click to expand...

Do you mean the new MAF (Managed Addin Framework) in 3.5?

That is a very powerful framework, but most likely completely
overkill, because relative complex.
Otherwise, you're
going to have to load the assembly explicitly, inspect it for relevant
types, and execute the code within all via reflection.
Click to expand...

Utilizing that the assembly contains a class implementing
a known interface to avoid reflection for calling the loaded
code is very common.

Arne
 
I meant :
I.e I want to load "System.Data.SqlClient dll" on runtime, and use some of
it's classes (such as SqlConnectionStringBuilder)

I will try the samples you gave.

Thanks :)
 
What I did for the sample you gave,
for MySql, I got the message :
=========================
Could not load file or assembly 'MySql.Data.MySqlClient' or one of its
dependencies. The system cannot find the file specified.
 
I meant :
I.e I want to load "System.Data.SqlClient dll" on runtime, and use some
of it's classes (such as SqlConnectionStringBuilder)
Click to expand...

Db provider factories exists to solve this problem using
builtin .NET code.

If you have to support .NET 1.x, then you can do it manually like
in this example:

using System;
using System.Reflection;
using System.Data;

namespace E
{
public class MainClass
{
public static void Test(string dllfnm, string conclznam, string
constr)
{
IDbConnection con =
(IDbConnection)Assembly.LoadFrom(dllfnm).CreateInstance(conclznam);
con.ConnectionString = constr;
con.Open();
IDbCommand cmd = con.CreateCommand();
cmd.CommandText = "SELECT * FROM T1";
IDataReader rdr = cmd.ExecuteReader();
while(rdr.Read()) {
int f1 = (int)rdr[0];
string f2 = (string)rdr[1];
Console.WriteLine(f1 + " " + f2);
}
con.Close();
}
public static void Main(string[] args)
{
Test(@"C:\InetPub\wwwroot\bin\MySql.Data.dll",
"MySql.Data.MySqlClient.MySqlConnection",
"Database=Test;Data Source=localhost;User Id=;Password=");
}
}
}

Arne
 
What I did for the sample you gave,
for MySql, I got the message :
=========================
Could not load file or assembly 'MySql.Data.MySqlClient' or one of its
dependencies. The system cannot find the file specified.
Click to expand...

Code?

What version of MySQL provider?

Where is your code and where is the MySQL provider?

Arne
 
Back
Top