Member Avatar for zagrijs

Hi I am new to the forums and to Python!

I am having trouble displaying a text menu in the following format
1: Name
2: Name
3: Name

It displays it correctly but then it gives an error message: Below is the code with output and error message.

#CreateMenu.py
#Create a standard text menu

#Create class menu

class TextMenu:
def __init__(self, listMenu):
self.listMenu = listMenu

#print menu
def __str__(self):
self.i = 1
self.index = len(self.listMenu)
while self.i < self.index:
print str(self.i) + ': ' + self.listMenu[self.i]
self.i = self.i + 1

#Test menu
list =
Menu = TextMenu(list)
print Menu

# Here is the output - with the error message
Evaluating CreateMenu.py
1: one
2: two
3: three
4: four
TypeError: __str__ returned non-string (type NoneType)

Any help would be appreciated.

PS: My code was indented - the indentation was removed when I posted

  • 3 Contributors
  • 4 Replies
  • 108 Views
  • 1 Day Discussion Span
  • Latest Post Latest Post by zagrijs
Member Avatar for zagrijs

I have worked on the program some more, added a few things and updated the TextMenu class - however after all text that I print it prints "none". I have attached the code.
Here is the output:

Calculator ver.0.1
Help!
Enter a number corresponding to the action you want.

Created by Zagrijs Venter

None # It prints none after the help method is run
1: one
2: two
3: three
4: four
None # it prints none after the TextMenu method is run

#CreateMenu.py
#Create a standard text menu

#Create class menu

class TextMenu:
    def __init__(self):
        pass
#print menu
    def __str__(self, listMenu):
        self.i = 1
        self.index = len(listMenu)
        for self.i in range(1, self.index):
            print str(self.i) + ': ' + listMenu[self.i]
                
#Create an inherited class for the submenus
class SubMenu(TextMenu):
    def __init__(self, listMenu):
        self.listMenu = listMenu
    def Menu1(self):
        pass
    
#Create a class for TextFiles:
class TextFileOpen:
    def __init__(self):
       pass
    def printTextFile(self, Name):
        self.textf = open(Name, 'r')
        self.strl = self.textf.read()
        self.textf.close()
        print self.strl
        
#Test TextFile
Help = TextFileOpen()
print Help.printTextFile('help.txt')

#Test menu
list = ['narf', 'one', 'two', 'three', 'four']
Menu = TextMenu()
print Menu.__str__(list)
Member Avatar for jrcagle

The indentation problem is frustrating, but is solved by use of the [ code="Python"] and [/code] tags.

The problem with the original TextMenu was that __str__ methods are not supposed to print things, but instead return a printable string. Like this:

class Thingy(object):
   def __init__(self):
        self.items = [0,1,2,3]

   def __str__(self):
        s = ""
        for x in self.items:
            s += str(x)
        return s

so, what you want to do is build up the return string and then pass it back to the caller (which may be a print statement, or a str() function, or whatever).

Jeff

Edited by mike_2000_17 because: Fixed formatting
Member Avatar for vegaseat

For posting Python code on Daniweb:
Please use the [code=python] and [/code] tag pair to enclose your python code.

Another note: Also make sure that the thread's title has something to do with your problem.

Member Avatar for zagrijs

Thanks

I have managed to fix the code now.

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.