Correctly go through property setter when init'ing Timer interval.

anntzer · anntzer · commit 5e3498f26e1c · 2020-04-17T00:20:42.000+02:00
The setter casts the interval to an int, which is required at least by
the tk backend.
diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
@@ -1059,8 +1059,9 @@ def __init__(self, interval=None, callbacks=None):
             `remove_callback` can be used.
         """
         self.callbacks = [] if callbacks is None else callbacks.copy()
-        self._interval = 1000 if interval is None else interval
-        self._single = False
+        # Set .interval and not ._interval to go through the property setter.
+        self.interval = 1000 if interval is None else interval
+        self.single_shot = False
         # Default attribute for holding the GUI-specific timer object
         self._timer = None
 
diff --git a/lib/matplotlib/tests/test_backends_interactive.py b/lib/matplotlib/tests/test_backends_interactive.py
@@ -114,7 +114,7 @@ def check_alt_backend(alt_backend):
 
 ax.plot([0, 1], [2, 3])
 
-timer = fig.canvas.new_timer(1)
+timer = fig.canvas.new_timer(1.)  # Test that floats are cast to int as needed.
 timer.add_callback(FigureCanvasBase.key_press_event, fig.canvas, "q")
 # Trigger quitting upon draw.
 fig.canvas.mpl_connect("draw_event", lambda event: timer.start())
