On 5/10/2018 2:12 PM, charmingold...@gmail.com wrote:
I'm learning to use TkInter in Python and came across this example program from
'Thinking in TkInter' (http://thinkingtkinter.sourceforge.net) - see below.
Two buttons 'button1' and 'button2' are defined. The bug is that event.widget
returns '.!frame.!button' from a button1 event.
The internal pathname of a widget is generated by tkinter for
interaction with tk. '.' is the name given to the root Tk widget.
Before a couple of years ago, children were given random 8(I
believe)-digit names. So you might have seen something like
.88023535.29038503. Now, the path component for a widget is '!' +
widgetName (+ number suffix if needed). A number suffix is only needed
to avoid duplication after the first widget of a given class for a
particular parent.
i.e. it somehow drops the '1' from the widget name.
There never was a '1' to be dropped.
Events on button2 are correctly reported.
Is this a bug or a feature?
<code>
from tkinter import *
class MyApp:
def __init__(self, parent):
self.myParent = parent
self.myContainer1 = Frame(parent)
self.myContainer1.pack()
button_name = "OK"
self.button1 = Button(self.myContainer1,
command=self.buttonHandler(button_name, 1, "Good
stuff!"))
This calls self.buttonHandler and binds the return value, None, to
command. Functions bound to 'command' must not require arguments. Add
'lambda:' before 'self' and the above will work. Nothing is printed
until you click the button and the printing is repeated each time you click.
# self.button1.bind("<Return>", self.buttonHandler_a(event, button_name,
1, "Good stuff!"))
Functions bound to events must take one argument, the event. Add
'lambda event:' before 'self' and the above works when the focus is on
button1 and you hit return.
Repeat both fixes for button 2.
self.button1.configure(text=button_name, background="green")
self.button1.pack(side=LEFT)
self.button1.focus_force() # Put keyboard focus on button1
button_name = "Cancel"
self.button2 = Button(self.myContainer1,
command=self.buttonHandler(button_name, 2, "Bad
stuff!"))
# self.button2.bind("<Return>", self.buttonHandler_a(event, button_name,
2, "Bad stuff!"))
self.button2.configure(text=button_name, background="red")
self.button2.pack(side=LEFT)
def buttonHandler(self, arg1, arg2, arg3):
print(" buttonHandler routine received arguments:",
arg1.ljust(8), arg2, arg3)
def buttonHandler_a(self, event, arg1, arg2, arg3):
print("buttonHandler_a received event", event)
self.buttonHandler(arg1, arg2, arg3)
print("\n"*100) # clear the screen
print("Starting program tt077.")
root = Tk()
myapp = MyApp(root)
print("Ready to start executing the event loop.")
root.mainloop()
print("Finished executing the event loop.")
</code>
--
Terry Jan Reedy
--
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