Getting coordinates from mouse click in QGIS3 in a plugin

Question

I'm trying to grab the coordinates from a click. If I type this code (obtained from Getting coordinates from mouse click in QGIS 3 (python plugin)):

def display_point(pointTool):
 try:
 print(pointTool.x(), pointTool.y())
 except AttributeError:
 pass
# a reference to our map canvas
canvas = iface.mapCanvas()
# this QGIS tool emits as QgsPoint after each click on the map canvas
pointTool = QgsMapToolEmitPoint(canvas)
pointTool.canvasClicked.connect(display_point)
canvas.setMapTool(pointTool)
display_point(pointTool)

in the python console it works perfectly. But if I place it inside my plugin class it does not work, don't even get the cross mouse pointer and I have no idea why is not working:

...
 def display_point(self, pt, bt):
 try:
 print(pt.x(), pt.y(), bt)
 except AttributeError:
 print("No attribute")
 def on_create_ignition_point(self):
 print("IN")
 canvas = self.iface.mapCanvas()
 pointTool = QgsMapToolEmitPoint(canvas)
 pointTool.canvasClicked.connect(self.display_point)
 canvas.setMapTool(pointTool)
 print('OUT')
...

the function on_create_ignition_point gets called from a toolbar button and the IN and OUT messages are printed. Also created a class like is explained in Getting coordinates of point on mouse click using PyQGIS with the same results.

Any hints on what I'm doing wrong?

• Ben W: In a plugin, should create instance attributes for canvas: self.canvas = self.iface.mapCanvas() and pointTool: self.pointTool = QgsMapToolEmitPoint(self.canvas) in the __init__ method of the main plugin class. Then create the signal/slot connection in the initGui method: self.pointTool.canvasClicked.connect(self.display_point). Finally, in your on_create_ignition_point() method, just set the canvas map tool: self.canvas.setMapTool(self.pointTool).
• Ben W: I answered a similar question here: gis.stackexchange.com/questions/403628/… Maybe you will find it useful.
• Jaume Figueras: Thank you for your answers, moving the variables to instance attributes solved the problem. Of course letting the point tool be a local variable was not a good idea.
• Matt: Perhaps you could create an answer with your working code and explanation of the changes you made. It will help future readers of this question.

Answer 1

Following the comments provided did the trick. Moving the local variables to instance attributes solved the problem.

The final code is this:

 if not (self._pointTool is None):
 self._pointTool.canvasClicked.disconnect()
 del self._pointTool
 self._previousTool = None
 self._pointTool = None
 # Store the previous tool in use b the user
 canvas = self._iface.mapCanvas()
 self._previousTool = canvas.mapTool()
 # Set the tool and onClick callback
 self._pointTool = QgsMapToolEmitPoint(canvas)
 self._pointTool.canvasClicked.connect(self.on_point_callback)
 canvas.setMapTool(self._pointTool)