Click here to Skip to main content
14,025,259 members
Click here to Skip to main content
Add your own
alternative version


40 bookmarked
Posted 24 Mar 2008
Licenced CPOL

Dynamic Loading Made Simple

, 24 Mar 2008
Rate this:
Please Sign up or sign in to vote.
An article demonstrating quite how easy dynamic loading it (and why you should use it).


Dynamic Loading is the process of loading code and using it at run time rather than at compile time. Why use it? Simple, dynamic loading makes the process of modifying a program and adding extra functionality later on easier (especially by third-party vendors). Furthermore it makes larger projects far more managable since each section of code functionality is seperate from each other. Many applications use this technique for implementation of plugins, e.g. Visual Studio and CIRIP (see demo link).

The included source shows how to load classes from dll files (dynamical link libraries) at runtime based upon a particular interface.

The Code

public static List<object> LoadAssemblies(String path, String interfaceName, bool recursive)
    List<object> output = new List<object>();

    String[] files = new String[0];
    if (recursive)
        files = Directory.GetFiles(path, "*.dll", SearchOption.AllDirectories);
        files = Directory.GetFiles(path, "*.dll", SearchOption.TopDirectoryOnly);

    foreach (String filename in files)
        Console.WriteLine("Loading " + filename);
            Assembly assembly = Assembly.LoadFrom(filename);

            foreach (Type t in assembly.GetTypes())
                if (t.IsClass && !t.IsAbstract && t.GetInterface(interfaceName) != null)
        catch (Exception err)
            Console.WriteLine("Loading fail:" + err.ToString());
            Console.WriteLine("Loading complete");

    return output;

The LoadAssemblies method loads in a single instance of each class implementing interfaceName in dll files found at the path (or in deeper folders if recursive = true is specified).

Using the Code

To use the code the following steps must be taken;

  1. Create an application where dynamic loading support is required
  2. Create a new class library (dll) with a copy of the interface all plugins will support
  3. Create an explit link from the application to the interface library
  4. Create new class libraries (dlls) containing classes which implement the interface
  5. Add the included code into the application
  6. During the load in period of the application call LoadAssemblies; using the path to the dlls & the fully qualified name of the interface (e.g. DNBSoft.InterfaceA).
  7. Foreach of the returned objects (cast to the interface once returned as the List<object>) call the relevant methods to link the plugin to the application.

Points of Interest

Did you learn anything interesting/fun/annoying while writing the code? Did you do anything particularly clever or wild or zany? No and no, however plugin support is VERY useful, and once you get the hang of it you'll use it alot.

It's the way forward!!!


Version - The one and only release


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Derek Bartram
Software Developer Rail Research UK
United Kingdom United Kingdom
I originally studied for a masters in engineering of software engineering at The University of Birmingham during 2000-2004, of which I received a 2:1. I continued at Birmingham University working with Civil Engineering and Rail Research UK where I am currently in my final year of a 3 year PhD project developing a Computational Intelligent Approach to Railway Intervention Planning. Although my work has a significant focus on railway engineering and associated practices much of my work is with data mining (on SQL Server 2008) and computational intelligence (CI) techniques. My key areas of expertise in CI are clustering algorithms (including Rival Penalised Competitive Learning) and evolutionary algorithms.

Outside of my formal work I enjoy testing the latest technologies such as .NET 3.5 and the many frameworks of which it comprises (mainly WPF). I have several projects on the go including a .NET and DirectX port of Quake 3 and many utility libraries. I also maintain an extensive website coded in Cold Fusion which is regularly updated; more information is available about me there.

You may also be interested in...

Comments and Discussions

GeneralMy vote of 5 Pin
eduMolaMazo21-Oct-11 0:55
membereduMolaMazo21-Oct-11 0:55 
GeneralUse AppDomain Pin
Yitzhak Gootvilig10-Apr-08 3:25
memberYitzhak Gootvilig10-Apr-08 3:25 
NewsAll DLL's get locked when loaded and it's clasess get instantiated, so no DLL can be dropped while the system is running! Pin
AndyHo7-Apr-08 14:55
professionalAndyHo7-Apr-08 14:55 
QuestionWhat about security? Pin
mght7-Apr-08 4:47
membermght7-Apr-08 4:47 
AnswerRe: What about security? Pin
Derek Bartram7-Apr-08 8:28
memberDerek Bartram7-Apr-08 8:28 
Generaldirections to #5 Pin
BillWoodruff25-Mar-08 6:53
mveBillWoodruff25-Mar-08 6:53 
GeneralRe: directions to #5 Pin
Derek Bartram25-Mar-08 9:29
memberDerek Bartram25-Mar-08 9:29 
GeneralRe: directions to #5 Pin
BillWoodruff25-Mar-08 14:24
mveBillWoodruff25-Mar-08 14:24 
GeneralVote of less than 5 Pin
Derek Bartram24-Mar-08 22:40
memberDerek Bartram24-Mar-08 22:40 
QuestionWhat about generics??? Pin
datenkabel24-Mar-08 19:36
memberdatenkabel24-Mar-08 19:36 
AnswerRe: What about generics??? Pin
Derek Bartram24-Mar-08 22:31
memberDerek Bartram24-Mar-08 22:31 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

Permalink | Advertise | Privacy | Cookies | Terms of Use | Mobile
Web06 | 2.8.190419.4 | Last Updated 24 Mar 2008
Article Copyright 2008 by Derek Bartram
Everything else Copyright © CodeProject, 1999-2019
Layout: fixed | fluid