Trying to learn Tkinter. Want help with the menu:

[chris99]

The code won't even display the root, let alone the menus. Even when the conversion works, nothing else does, so what do I do?

from Tkinter import *
root = Tk()
def hello():
    print "Hello!"
def metres_to_centimetres(metre,cm):
    metre = input("Put in a distance in metres: ")
    cm = metre*100
    print "Distance in Centimetres = ",cm
 
menubar = Menu(root)
filemenu = Menu(menubar, tearoff=0)
filemenu.add_command(label="Hello", command=hello)
filemenu.add_command(label="M to Cm", command=metres_to_centimetres(metre,cm))
filemenu.add_separator()
filemenu.add_command(label="Exit", command=root.quit)
menubar.add_cascade(label="File", menu=filemenu)
root.config(menu=menubar)
mainloop()

Where have I gone wrong? I was altering code from a tutorial.

[chris99]

To update the problem, the "def metres_to_centimetres" runs first, then the gui displays, then the "M to cm" button does nothing while "hello" works perfectly.

[Ene Uran]

Several problems with your program, I corrected some of them:

from Tkinter import *

root = Tk()

def hello():
    print "Hello!"

# removed unneeded arguments (metre,cm)
def metres_to_centimetres():
    metre = input("Put in a distance in metres: ")
    cm = metre*100
    print "Distance in Centimetres = ",cm
 
menubar = Menu(root)
filemenu = Menu(menubar, tearoff=0)
filemenu.add_command(label="Hello", command=hello)

# command accepts a function object but not a function call
# to pass any arguments you have to wrap the object in lambda
#filemenu.add_command(label="M to Cm", command=metres_to_centimetres(metre,cm))  # gives error
# actually you don't need to pass any arguments
filemenu.add_command(label="M to Cm", command=metres_to_centimetres)

filemenu.add_separator()
filemenu.add_command(label="Exit", command=root.quit)
menubar.add_cascade(label="File", menu=filemenu)
root.config(menu=menubar)
mainloop()

Now the major problem is that you are mixing console only functions like print and input with a GUI environment. In a GUI program you use widget Label for prompts and results, and widget Entry for data entry/input or display. Actions are generally done with a button click. Here is an example:

# example of a labeled data entry, a button and a result label
# use grid to position widgets, also set cursor to focus on entry
# a rather generic Tkinter GUI template for calculations

from Tkinter import *

def calculate():
    try:
        # get the enter1 value
        # use float() for either float or integer entry
        num1 = float(enter1.get())
        # do the calculation
        result = num1 * 100
        # display the result string
        # use str() to convert numbers to string for concatination with +
        label2.config(text=str(num1) + 'meters = ' + str(result) + 'cm')
    except ValueError:
        label2.config(text='Enter a numeric value!')

root = Tk()

# data entry with a prompt label
label1 = Label(root, text='Enter distance in meters:')
label1.grid(row=0, column=0)
enter1 = Entry(root, bg='yellow')
enter1.grid(row=1, column=0)

# do the calculation by clicking the button
btn1 = Button(root, text='Calculate Result', command=calculate)
btn1.grid(row=2, column=0)

# display the result in this label
label2 = Label(root, bg='green')
label2.grid(row=3, column=0)

# start cursor in enter1
enter1.focus()

root.mainloop()

GUI/Windows programming is a mildly different world. I would get my Python basics under my belt before getting too deep into GUI.

[chris99]

It says There is no attribute Tk, even though the command is right where you put it. Here's my program for another update:

from Tkinter import *
def calculate():
    try:
        metre = float(enter1.get())
        result = metre * 100
        label2 = Label(calculate, bg="blue")
        label2.config(text=str(metre)+ 'meters = ' + str(result)+'cm')
    except ValueError:
        label2.config(text="Enter a numeric value!")
    
root = Tk()
                      
label1 = Label(root, text="Enter distance in metres: ")
label1.grid(row=0, column=0)
enter1 = Entry(root, bg="Yellow")
enter1.grid(row=1, column=0)
btnl = Button(root, text="Calculate Result", command=calculate)
btnl.grid(row=2, column=0)
mainloop()

Where is my mistake this time?

[vegaseat]

See my comments in the code ...

from Tkinter import *
def calculate():
    try:
        metre = float(enter1.get())
        result = metre * 100
        #label2 = Label(calculate, bg="blue")  # error here
        label2 = Label(root, bg="blue")        # black text on blue is hard to see!
        label2.grid(row=3, column=0)           # this was missing
        label2.config(text=str(metre)+ 'meters = ' + str(result)+'cm')
    except ValueError:
        label2.config(text="Enter a numeric value!")
    
root = Tk()
                      
label1 = Label(root, text="Enter distance in metres: ")
label1.grid(row=0, column=0)
enter1 = Entry(root, bg="Yellow")
enter1.grid(row=1, column=0)
btnl = Button(root, text="Calculate Result", command=calculate)
btnl.grid(row=2, column=0)
mainloop()

[vegaseat]

You can replace console based things like print and input with popup dialog boxes, then you can use the menu you constructed ...

from Tkinter import *
from tkMessageBox   import showinfo
from tkSimpleDialog import askfloat

root = Tk()

def hello():
    # print "Hello!"  # console only
    showinfo(None, "Hello!")
    
def meters_to_centimeters():
    # meter = input("Put in a distance in meters: ")  # console only
    meter = askfloat(None, "Put in a distance in meters:")
    cm = meter * 100
    # print "Distance in Centimeters = ",cm
    showinfo(None, "Distance in Centimeters = " + str(cm))
 
menubar = Menu(root)
filemenu = Menu(menubar,  tearoff=0)
filemenu.add_command(label="Hello", command=hello)
filemenu.add_command(label="M to Cm", command=meters_to_centimeters)
filemenu.add_separator()
filemenu.add_command(label="Exit", command=root.quit)
menubar.add_cascade(label="File", menu=filemenu)
root.config(menu=menubar)
root.mainloop()

Sorry, had to use meter instead of metre, a habit of mine.

[chris99]

Thanks everyone. I'll look out for the submissions Ene Uran submits into the Beginner programs thread.