What is the difference between parent.Bind and widget.Bind in wxPython

Question

import wx

class MyPanel(wx.Panel):

    def __init__(self, parent):
        super().__init__(parent)
        btn = wx.Button(self, label="Press me")
        btn.Bind(wx.EVT_BUTTON, self.on_button_press)

    def on_button_press(self, event):
        print("You pressed the button")

class MyFrame(wx.Frame):

    def __init__(self):
        super().__init__(parent=None, title="Hello wxPython")
        panel = MyPanel(self)
        self.Show()

if __name__ == "__main__":
    app = wx.App(redirect=False)
    frame = MyFrame()
    app.MainLoop()

In the code above we used btn.Bind for binding wx.Button to wx.EVT_BUTTON.
if instead, we use this way: self.Bind(wx.EVT_BUTTON, self.on_button_press, btn)
The result will be the same as above. Now my question is the difference between self.Bind and btn.Bind.

Answer 1

Each widget has an Id.
Events when triggered, pass the Id of the triggering widget, in this case a button.
Binding an event to a function can be specific or generic i.e. a specific widget or any widget that fires that event type.
In short, in this case, the self.Bind binds any button event unless you specify a widget ID.
See: https://docs.wxpython.org/events_overview.html
Hopefully, the code below will help explain.
N.B. event.Skip() says don't stop at this event, see if there are more events to process.

import wx

class MyPanel(wx.Panel):

    def __init__(self, parent):
        super().__init__(parent)
        btn1 = wx.Button(self, label="Press me 1", pos=(10,10))
        btn2 = wx.Button(self, label="Press me 2", pos=(10,50))
        Abtn = wx.Button(self, label="Press me", pos=(10,90))

    # Bind btn1 to a specific callback routine
        btn1.Bind(wx.EVT_BUTTON, self.on_button1_press)
    # Bind btn2 to a specific callback routine specifying its Id
    # Note the order of precedence in the callback routines
        self.Bind(wx.EVT_BUTTON, self.on_button2_press, btn2)
    # or identify the widget via its number
    #    self.Bind(wx.EVT_BUTTON, self.on_button2_press, id=btn2.GetId())
    # Bind any button event to a callback routine
        self.Bind(wx.EVT_BUTTON, self.on_a_button_press)

    # button 1 pressed
    def on_button1_press(self, event):
        print("You pressed button 1")
        event.Skip()

    # button  2 pressed
    def on_button2_press(self, event):
        print("You pressed button 2")
        event.Skip()

    # Any button pressed
    def on_a_button_press(self, event):
        print("You pressed a button")
        event.Skip()

class MyFrame(wx.Frame):

    def __init__(self):
        super().__init__(parent=None, title="Hello wxPython")
        panel = MyPanel(self)
        self.Show()

if __name__ == "__main__":
    app = wx.App(redirect=False)
    frame = MyFrame()
    app.MainLoop()