Python Tkinter：解析时出现意外的EOF

Question

I got the error unexpected EOF while parsing when i'm trying to create a conversion program with tkinter. Here is my code:

from tkinter import *
from tkinter.ttk import *


class conversion:

 def centi():

   def centiMet():
    meStr=a.get()
    meStrc = eval(meStr)
    con=meStrc/100
    conS=str(con)
    CenMet2=Label(root,text=conS + " Meters",font="CenturyGothic 12 bold").pack()
    return

 rootCm= Tk()
 a =  StringVar()
 rootCm.geometry("500x300")
 rootCm.title("Quick Reference Application - Version 0.1.8 [alpha] ")
 label1= Label(rootCm,text="Unit Conversions",font="CenturyGothic 17 bold").pack()
 inputCm= Entry(rootCm,textvariable=a).pack()
 convButton1= Button(rootCm,text="Convert!",command = centiMet).pack()


root= Tk()

root.geometry("500x300")
root.title("Quick Reference Application - Version 0.1.8 [alpha] ")

label1= Label(root,text="Unit Conversions",font="CenturyGothic 17 bold").pack()

CenMet1= Label(root,text="Please select the type you want!!",font="CenturyGothic 12 bold").pack()
convButton1= Button(root,text="Centimeters to Meters",command = conversion.centi).pack()

The error will show after you clicked the centimeter to meter button and try to convert. It works fine before i tried to make a button to initiate a new window for the cm to meters. Does anyone have any suggestion?

Answer 1

As you noticed, the problem seems to be with the second Tk() element. I am not 100% sure why this is the case, but it seems to work if you use a Toplevel window instead.

class conversion:
    def centi():
        def centiMet():
            meStr = a.get()
            con = float(meStr) / 100
            Label(rootCm, text="{} Meters".format(con), font="CenturyGothic 12 bold").pack()
        rootCm = Toplevel()
        rootCm.geometry("500x300")
        a =  StringVar()
        Label(rootCm, text="Unit Conversions", font="CenturyGothic 17 bold").pack()
        Entry(rootCm, textvariable=a).pack()
        Button(rootCm, text="Convert!", command=centiMet).pack()

Some more pointers:

• don't use eval if it can be avoided; use float instead
• label = Label(...).pack() will assign the result of pack() to label , not the actual label; also, you do not seem to need those variables anyway
• not sure whether this was intentional or not, but you added the result label to the original root, not to the popup-window

---

If you want to reuse the same label when converting multiple measures, use another StringVar :

class conversion:
    def centi():
        def centiMet():
            b.set("{} Meters".format(float(a.get()) / 100))
        ...
        b = StringVar()
        Label(rootCm, textvariable=b, font="CenturyGothic 12 bold").pack()