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https://github.com/rdbende/flake8-tkinter

A flake8 plugin that helps you write better Tkinter code
https://github.com/rdbende/flake8-tkinter

code-quality flake8 flake8-extension flake8-plugin linter linter-plugin tkinter

Last synced: 6 months ago
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A flake8 plugin that helps you write better Tkinter code

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README 

          
# flake8-tkinter



A [flake8](https://github.com/PyCQA/flake8) plugin that helps you write better Tkinter code



_Project idea by [@insolor](https://github.com/insolor)_



## Installation



```

pip install flake8-tkinter

```



## List of warnings



Common mistakes

- **`TK102`**: Using multiple mainloop calls is unnecessary. One call is perfectly enough. ([example](#tk102))

- **`TK111`**: Calling `callback_handler()` instead of passing the reference for on-click or binding callback. ([example](#tk111))

- **`TK112`**: Calling `callback_handler()` with arguments instead of passing the reference for on-click or binding callback. If you need to call `callback_handler` with arguments, use lambda or functools.partial. ([example](#tk112))

- **`TK131`**: Assigning result of geometry manager call to a variable. ([example](#tk131))



Best practices

- **`TK141`**: Using bind without `add=True` will overwrite any existing bindings to this sequence on this widget. Either overwrite them explicitly with `add=False` or use `add=True` to keep existing bindings. ([example](#tk141))

- **`TK142`**: Creating tag bindings in a loop can lead to memory leaks. Store the returned command names in a list to clean them up later. ([example](#tk142))

- **`TK201`**: Using `from tkinter import *` is generally a bad practice and discouraged. Use `import tkinter as tk` or simply `import tkinter` instead. ([example](#tk201))

- **`TK202`**: Using `from tkinter.ttk import *` is generally a bad practice and discouraged. Use `from tkinter import ttk` instead. ([example](#tk202))

- **`TK211`**: Using `import tkinter.ttk as ttk` is pointless. Use `from tkinter import ttk` instead. ([example](#tk211))

- **`TK221`**: Using tkinter.TRUE, tkinter.FALSE, etc. is pointless. Use an appropriate Python boolean instead. ([example](#tk221))

- **`TK251`**: Using `tkinter.Message` widget. It's redundant since `tkinter.Label` provides the same functionality. ([example](#tk251))



Code quality

- **`TK304`**: Value for `add` in bind methods should be a boolean. ([example](#tk304))



Opinionated warnings

- **`TK504`**: Using a tkinter constant. Use a string literal instead (disabled by default). ([example](#tk504))



## Examples



### TK102

```python

# Bad

def foo():

    top = tk.Toplevel()

    ...

    top.mainloop()



root.mainloop()



# Good

def foo():

    top = tk.Toplevel()

    ...

    

root.mainloop()

```



### TK111

```python

# Bad

tk.Button(..., command=foo())

button.config(command=bar())

button.bind("", baz())



# Good

tk.Button(..., command=foo)

button.config(command=bar)

button.bind("", baz)

```



### TK112

```python

# Bad

tk.Button(..., command=foo(arg, kwarg=...))

button.config(command=bar(arg, kwarg=...))

button.bind("", baz(arg, kwarg=...))



# Good

tk.Button(..., command=lambda: foo(arg, kwarg=...))

button.config(command=lambda: bar(arg, kwarg=...))

button.bind("", lambda e: baz(arg, kwarg=...))

```



### TK131

```python

# Bad

btn = tk.Button().grid()



# Good

btn = tk.Button()

btn.grid()

```



### TK201

```python

# Bad

from tkinter import *



# Good

import tkinter

# OR

import tkinter as tk

```



### TK202

```python

# Bad

from tkinter.ttk import *



# Good

from tkinter import ttk

```



### TK211

```python

# Bad

import tkinter.ttk as ttk



# Good

from tkinter import ttk

```



### TK221

```python

# Bad

w.pack(expand=tk.TRUE)

w.pack(expand=tk.FALSE)

w.pack(expand=tk.YES)

w.pack(expand=tk.NO)

w.pack(expand=tk.ON)

w.pack(expand=tk.OFF)



# Good

w.pack(expand=True)

w.pack(expand=False)

```



### TK141

```python

# Bad

w.bind("", foo)



# Good

w.bind("", foo, add=True)

# OR

w.bind("", foo, add=False)

```



### TK142

```python

# Bad

for index, foo in enumerate(foos):

    w.tag_bind(f"bar_{index}", "", baz)

    

# Good

for index, foo in enumerate(foos):

    tcl_command = w.tag_bind(f"bar_{index}", "", baz)

    bindings.append(tcl_command)  # Clean them up later with `.deletecommand()`

```



### TK251

_Yes, there's some minor diffrence in text wrapping, but that can be easily fixed

```python

# Bad

w = tkinter.Message()



# Good

w = tkinter.Label()

```



### TK304

```python

# Bad

w.bind("", foo, add="+")



# Good

w.bind("", foo, add=True)

```



### TK504

```python

# Bad

w.pack(side=tkinter.BOTTOM, fill=tkinter.BOTH)



# Good

w.pack(side="bottom", fill="both")

```



## Planned warnings



- Common mistakes (TK101-TK179)

    - `TK101`: Using multiple `tkinter.Tk` instances. Child windows must be created from `tkinter.Toplevel`.

    - `TK103`: Suggest refactoring code that uses `.update()`, as it's usually pointless, [potentially harmful](https://wiki.tcl-lang.org/page/Update+considered+harmful), and considered a code smell.

    - `TK113`: Callback handler should be a callable

    - `TK121`: Using `time.sleep()` in tkinter code. Use `.after()` in some form instead.

    - `TK122`: Using an infinite loop in callback handler. Propose to use recursive function with `.after()`.

    - `TK???`: Suggest keeping reference of local `PhotoImage` instance to avoid GC.

    - `TK151`: Don't use `w.setup()` directly. Use init args, or `w.configure()`.

    - Extend `TK111` and `Tk112` to check in `w.after()` calls.



- Cross platform (TK181-TK199)

    - `TK181`: Using `` binding. It doesn't work on Linux with Tk 8.6 (use button4-5 instead)

    - `TK182`: Using `` binding. It doesn't work on Linux (use `` instead)

    - `TK183`: Using `` binding. It doesn't work on Windows (use `` instead)

    - `TK184`: Binding to control or alt with constant values. It probably won't work on macOS.

    - `TK191`: Not calling `wait_visibility` before `wm_attributes("-alpha")`.

    - `TK192`: Using `w.state("zoomed")`. It throws an error on Linux (and on mac too?). Use `wm_attributes("-zoomed", True)`



- Best practices (TK201-TK299)

    - `TK222`: Using `tk.N+tk.S+tk.E+tk.W` and combinations like that. Use `tk.NSEW`, or some other constant instead.

    - `TK241`: Creating a widget without parent specified, and there is a container in the same scope.

    - `TK252`: Using `tkinter.Menu` without `tearoff=False`

    - `TK261`: Using subsequent `wm_attributes` calls. It can take value pairs.



- Code quality (TK301-TK399)

    - `TK301`: Suggest using more clear binding sequences, like `` instead of `<1>` and `` instead of ``.

    - `TK302`: Suggest using more clear `tkinter.Text` indexes, like `end - 1 chars` instead of `end-1c`.

    - `TK303`: Using a float as `tkinter.Text` index. It works because how Tkinter translates Python objects to Tcl, but it shouldn't.



- OO (TK401-TK499)

    - `TK401`: Consider refactoring a huge app with OOP.

    - `TK402`: Consider refactoring widget into separate class.

    

- Opinionated rules (TK501-TK599)

    - `TK501`: Calling `mainloop()` on something other than the root window.

    - `TK502`: Using things like `root.wm_title()`. Use `root.title()`. (But there should be exceptions, like `wm_attributes`, and instead warn on plain `attributes`)

    - `TK503`: Using subscripting for widget cget and configure. Use `.cget()` and `.configure()` instead.



## Development

1. Clone the repo

2. Set up a virtual environment, activate, and install `flake8` and `pytest` in it

3. Run `pip install -e .` to install `flake8-tkinter` in editable format

4. Run `python3 -m pytest` to test your changes