Tkinter is the standard GUI (Graphical User Interface) package that comes bundled with most Python installations. However, if you are working on a codebase that needs to support both Python 2 and Python 3, or if you are porting an older project, you will quickly run into a common stumbling block: the import naming change.

In this guide, we’ll look at why this change happened and how to write code that works seamlessly across both versions of Python.

The Naming Shift

The main difference between the two versions is a simple case change:

• In Python 2, the module is named Tkinter (capital ‘T’).
• In Python 3, the module was renamed to tkinter (lowercase ‘t’) as part of a larger effort to standardize module naming conventions (PEP 8).

Python 2 Syntax

import Tkinter
root = Tkinter.Tk()

Python 3 Syntax

import tkinter
root = tkinter.Tk()

This tiny difference is enough to cause an ImportError that crashes your program if you try to run Python 2 code in a Python 3 environment.

The Universal Fix: Try/Except Block

The most robust way to handle this without requiring external libraries is to use a try...except block. This allows your script to attempt the Python 3 import first and fall back to Python 2 if it fails.

try:
    # Attempt Python 3 import
    import tkinter as tk
except ImportError:
    # Fallback for Python 2
    import Tkinter as tk

# Now you can use 'tk' regardless of the Python version
root = tk.Tk()
root.title("Cross-Platform Tkinter")
root.mainloop()

Why use as tk?

By aliasing the module to tk, you ensure that the rest of your code remains identical. You don’t have to keep checking which version of the module you are using; you just call tk.Button(), tk.Label(), etc.

Handling Submodules (Advanced)

Sometimes you need specific submodules like messagebox or filedialog. These also changed significantly in Python 3. In Python 2, they were often separate modules like tkMessageBox.

Here is how you handle them for cross-compatibility:

try:
    # Python 3
    from tkinter import messagebox
    from tkinter import filedialog
except ImportError:
    # Python 2
    import tkMessageBox as messagebox
    import tkFileDialog as filedialog

# Example usage
messagebox.showinfo("Hello", "This works in both versions!")

Conclusion

Tackling the Python 2 and 3 divide in Tkinter is easy once you know the try/except pattern. By using this approach, you can write modern GUI applications that are accessible to users on older systems while remaining fully compatible with the latest Python releases.

If you’re starting a brand new project, we highly recommend sticking exclusively to Python 3, as Python 2 has reached its end-of-life (EOL). However, for maintenance and porting, these tips are essential tools in your Python developer toolkit.