Le portail francophone de la géomatique

#aprés l'elaboration du plugin j'ai essaye de modifier le code pour que l'extension me permet d'afficher les couches actives mais je pense que il y a une erreur
#voila le code :

# Import the PyQt and QGIS libraries
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from qgis.core import *
from qgis.mapcanvas import*
# Initialize Qt resources from file resources.py
import resources_rc
# Import the code for the dialog
from izisse_testdialog import izisse_testDialog
import os.path


class izisse_test:

    def __init__(self, iface):
        # Save reference to the QGIS interface
        self.iface = iface
        # initialize plugin directory
        self.plugin_dir = os.path.dirname(__file__)
        # initialize locale
        locale = QSettings().value("locale/userLocale")[0:2]
        localePath = os.path.join(self.plugin_dir, 'i18n', 'izisse_test_{}.qm'.format(locale))

        if os.path.exists(localePath):
            self.translator = QTranslator()
            self.translator.load(localePath)

            if qVersion() > '4.3.3':
                QCoreApplication.installTranslator(self.translator)

        # Create the dialog (after translation) and keep reference
        self.dlg = izisse_testDialog()

    def initGui(self):
        # Create action that will start plugin configuration
        self.action = QAction(
            QIcon(":/plugins/izisse_test/icon.png"),
            u"izisse.....", self.iface.mainWindow())
        # connect the action to the run method
        self.action.triggered.connect(self.run)

        # Add toolbar button and menu item
        self.iface.addToolBarIcon(self.action)
        self.iface.addPluginToMenu(u"&izisse", self.action)

    def unload(self):
        # Remove the plugin menu item and icon
        self.iface.removePluginMenu(u"&izisse", self.action)
        self.iface.removeToolBarIcon(self.action)

    # run method that performs all the real work
    def run(self):
        # show the dialog
        self.dlg.show()
        # Run the dialog event loop
        result = self.dlg.exec_()
        # See if OK was pressed
        if result == 1:
        # show the active layers
     mapCanvas = self.iface.mapCanvas()
     if mapCanvas.layerCount() == 0: QMessageBox.warning(self.iface.mainWindow(), "izisse_test Plugin" , ("No active layer found"), QMessageBox.Ok) return layerName = ""
     for i in range(mapCanvas.layerCount()-1,-1,-1): layer = mapCanvas.layer(i) layerName += layer.name()+"\n"
     # create and show the dialog
     dlg = showActiveLayerDialog() dlg.ui.plainTextEdit.appendPlainText(layerName) dlg.show() result = dlg.exec_()
     # See if OK was pressed
     if result == 1: QMessageBox.warning(self.iface.mainWindow(), "izisse_test Plugin", ("Voulez allez quitter le plugin !"), QMessageBox.Ok)