Reflection and Plugins

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

ThE_lOtUs at 2007-9-8 >

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.

ThE_lOtUs at 2007-9-8 >

Hey ThE_lOtUs can you post an example code for the plugin?

Thanks

Marc

mdooley at 2007-9-8 >

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

mdooley at 2007-9-8 >

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/

ThE_lOtUs at 2007-9-8 >