Nuevos Programadores

Private Sub CargarPropiedades()
	Dim propiedades1 As New List(Of String)
	Dim propiedades2 As New List(Of String)
 
	' Recorremos todos los miembros de la clase
	For Each propiedad As System.Reflection.MemberInfo In System.Reflection.Assembly.GetExecutingAssembly.GetType("Objeto").GetMembers()
		' Filtramos para seleccionar solamente las propiedades
		If propiedad.MemberType = System.Reflection.MemberTypes.Property Then
			propiedades1.Add(propiedad.Name)
			propiedades2.Add(propiedad.Name)
		End If
	Next
 
	Me.cmbField1.DataSource = propiedades1 'Asignamos el DataSource a nuestros ComboBox
	Me.cmbField2.DataSource = propiedades2
End Sub

Private Sub btnSelect_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSelect.Click
	If ValidarEntrada() Then ' Chequeaar que el usuario haya ingresado todos los valores necesarios
		Try
			' LINQ To Objects
			Dim resSelect = From obj In mObjetos _
				Select obj _
				Where obj.GetType().GetProperty(Me.cmbField1.SelectedItem.ToString()).GetValue(obj, Nothing) = Me.txtCond1.Text _
				And (IIf(cmbJoin.SelectedItem = "AND", obj.GetType().GetProperty(Me.cmbField2.SelectedItem.ToString()).GetValue(obj, Nothing) = Me.txtCond2.Text, True)) _
				Or (IIf(cmbJoin.SelectedItem = "OR", obj.GetType().GetProperty(Me.cmbField2.SelectedItem.ToString()).GetValue(obj, Nothing) = Me.txtCond2.Text, False))
 
			Me.lstSelect.Items.Clear() ' Limpiar la lista antes de mostrar el resultado de la consulta
			For Each item In resSelect
				Me.lstSelect.Items.Add(item)
			Next
		Catch ex As Exception
			If MessageBox.Show(String.Format("Error: {0}{1}Desea ver más información acerca de este error?", ex.Message.ToString(), Environment.NewLine), "Error", MessageBoxButtons.YesNo, MessageBoxIcon.Asterisk) = Windows.Forms.DialogResult.Yes Then
				MessageBox.Show(ex.ToString(), "Detalle del error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
			End If
		End Try
	End If
End Sub

    Private Sub bgwCargaPlugins_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bgwCargaPlugins.DoWork
        Dim DirectorioPlugins As String = String.Format("{0}{1}", Threading.Thread.GetDomain().BaseDirectory, "plugins")
        If Directory.Exists(DirectorioPlugins) Then
            For Each _dir As String In Directory.GetDirectories(DirectorioPlugins)
                Try
                    Dim aux As System.Collections.Generic.KeyValuePair(Of String, String) = PluginLoader.CargarPluginDesdeDirectorio(_dir)
                    _pluginsEncontrados.Add(aux.Key, aux.Value)
                Catch ex As Exception
                    Trace.WriteLine(ex.ToString())
                End Try
            Next
        Else
            Trace.WriteLine("El directorio de plugins no existe.")
        End If
    End Sub
 
    Private Sub bgwCargaPlugins_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles bgwCargaPlugins.RunWorkerCompleted
        If _pluginsEncontrados.Count > 0 Then
            mostrarMenuDePlugins()
        End If
    End Sub

    ' Método que carga los items en el menú
    Public Sub mostrarMenuDePlugins()
        For Each p As System.Collections.Generic.KeyValuePair(Of String, String) In _pluginsEncontrados
            Dim aux As System.Windows.Forms.ToolStripMenuItem = Me.PluginsToolStripMenuItem.DropDownItems.Add(p.Key)
            AddHandler aux.Click, AddressOf PluginMenuClick
        Next
        Me.PluginsToolStripMenuItem.Enabled = True
    End Sub
 
    ' handler para el evento click de cada item del menú plugins
    Public Sub PluginMenuClick(ByVal sender As Object, ByVal e As System.EventArgs)
        Try
            Dim plugin As Form = PluginLoader.InstanciarPlugin(_pluginsEncontrados.Item(sender.ToString()), sender.ToString())
            plugin.MdiParent = Me
            plugin.Show()
        Catch ex As Exception
 
        End Try
    End Sub

Imports System.IO
 
Public Class PluginLoader
    Public Shared Function CargarPluginDesdeDirectorio(ByVal Directorio As String) As System.Collections.Generic.KeyValuePair(Of String, String)
        Dim aux As System.Collections.Generic.KeyValuePair(Of String, String) = Nothing
 
        'Busco solo los archivos .dll en el directorio especificado
        Dim archivos() As String = Directory.GetFiles(Directorio, "*.dll")
        If archivos.Length > 0 Then
            For Each dll As String In archivos
                Try
                    Dim assembly As System.Reflection.Assembly = System.Reflection.Assembly.LoadFrom(dll)
                    'Recorro los tipos que se encuentran en la dll cargada
                    For Each t As Type In assembly.GetTypes()
                        Try
                            'cargo solo los que son derivados de Form
                            If t.BaseType Is GetType(Form) Then
                                aux = New System.Collections.Generic.KeyValuePair(Of String, String)(t.Name, assembly.Location)
                            End If
                        Catch ex As Exception
                            Trace.WriteLine(ex.ToString())
                        End Try
                    Next
                Catch ex As Exception
                    Trace.WriteLine(ex.ToString())
                End Try
            Next
        End If
        Return aux
    End Function
 
    Public Shared Function InstanciarPlugin(ByVal RutaDll As String, ByVal PluginName As String, Optional ByVal ExtraData As Object = Nothing) As Form
        Dim TipoPlugin As Type
        Dim frm As Form
 
        Dim PluginAssembly As System.Reflection.[Assembly] = System.Reflection.[Assembly].LoadFrom(RutaDll)
        TipoPlugin = PluginAssembly.GetType(PluginName, False, True)
 
        If Not TipoPlugin Is Nothing Then
            Dim Instancia As Object
            'ExtraData se puede utilizar para pasar argumentos al constructor
            If ExtraData Is Nothing Then
                Instancia = Activator.CreateInstance(TipoPlugin)
            Else
                Dim arg() As Object = {ExtraData}
                Instancia = Activator.CreateInstance(TipoPlugin, arg)
            End If
 
            frm = CType(Instancia, Form)
        Else
            'En caso de error devuelvo un form cualquiera con el texto de error
            frm = New Form()
            frm.Text = "Error cargando el plugin"
        End If
 
        Return frm
    End Function
End Class