Reflection and Plugins

Reflection and Plugins

• JCesar

  To add to the information

  interface_name is the actual class name of an interface

      Public Interface ICell

          Property Data() As Object
          Property X() As Integer
          Property Y() As Integer
          Property Style() As String

          Sub ProcessCell()

      End Interface

  interface_name = "YourNamespace.ICell"

  Because each plugin must inherit from an interface to have the same basic signature.

  This also help the developper of the plugin, cause he will know what function you will call.

  
  
  

• Binayak67839

  you got it.. here is the code I use, it's VB and can be easely converted to C++
  -------------
  
  Imports System.IO
  Imports System.Reflection

  Public Class PluginEngine

      Public Shared Function FindPlugins(ByVal path As String, ByVal interface_name As String) As ArrayList

          Dim plugins As ArrayList
          Dim dll_list() As String
          Dim index As Integer
          Dim cur_dll As [Assembly]

          plugins = New ArrayList
          dll_list = Directory.GetFileSystemEntries(path, "*.dll")

          For index = 0 To dll_list.Length - 1
              Try
                  cur_dll = [Assembly].LoadFrom(dll_list(index))
                  ExamineAssembly(cur_dll, interface_name, plugins)
              Catch e As Exception
              End Try
          Next

          Return plugins
      End Function

      Private Shared Sub ExamineAssembly(ByVal cur_dll As [Assembly], ByVal interface_name As String, ByVal plugins As ArrayList)

          Dim cur_type As Type
          Dim cur_interface As Type
          Dim plugin As AvailablePlugin

          For Each cur_type In cur_dll.GetTypes
              If cur_type.IsPublic = True Then
                  If Not ((cur_type.Attributes And TypeAttributes.Abstract) = TypeAttributes.Abstract) Then
                      cur_interface = cur_type.GetInterface(interface_name, True)

                      If Not (cur_interface Is Nothing) Then
                          plugin = New AvailablePlugin
                          plugin.AssemblyPath = cur_dll.Location
                          plugin.FullClassName = cur_type.FullName

                          plugins.Add(plugin)
                      End If
                  End If
              End If
          Next

      End Sub

      Public Shared Function CreateInstance(ByVal plugin As AvailablePlugin) As Object

          Dim cur_dll As [Assembly]
          Dim cur_plugin As Object

          Try
              cur_dll = [Assembly].LoadFrom(plugin.AssemblyPath)
              cur_plugin = cur_dll.CreateInstance(plugin.FullClassName)
          Catch e As Exception
              Throw e ''Return Nothing
          End Try

          Return cur_plugin
      End Function

  End Class
  
  --------------
  
  Public Class AvailablePlugin

      Private _assembly_path As String
      Private _class_name As String

      Public Property AssemblyPath() As String
          Get
              Return _assembly_path
          End Get
          Set(ByVal Value As String)
              _assembly_path = Value
          End Set
      End Property

      Public Property FullClassName() As String
          Get
              Return _class_name
          End Get
          Set(ByVal Value As String)
              _class_name = Value
          End Set
      End Property

      Public ReadOnly Property ClassName() As String
          Get
              Dim index As Integer

              index = _class_name.LastIndexOf(".")

              If index > 0 Then
                  Return _class_name.Substring(index + 1)
              End If

              Return _class_name
          End Get
      End Property

  End Class
  

  
  
  

• Ice Romeo

  I got this code from a fiew source on the net.

  http://divil.co.uk/net/articles/plugins/plugins.asp

  http://wwww.developerfusion.com/show/4371/1/

  
  
  

• btrefonas

  I already posted the code for my plugin engine.
  
  

• Martin Maierhofer

  I got that and I understand all of it but the interface part....it makes no sence how I impliment it into the plugin. I have been trying to get a plugin program working for nearly 2 months and I am just.....lost beyond belief. Your code is the first code that is making at least a little since.

  Thanks

  Marc

  
  

• Jan_B-K

  Thanks much. I will study this over.
  

• Utkarsh Shigihalli

  That is something that I am concerned about, making function calls. It seems like the code will not be as readable, self-documenting, as when not using plug-ins. More like making calls via an array index.
  Jeff
  

• jirikraus

  Hey ThE_lOtUs can you post an example code for the plugin

  Thanks

  Marc

  
  

• Trebormac

  I am going to be loosing internet here in about 10 min and I dont know when Ill be on again, so thanks ahead of time.

  Marc

  
  
• Reflection and Plugins