Ctrl+Shift key combination in Python

Question

I am working on a snippet that requires user interaction: either an Esc press or a Ctrl+Shift press.

I am struggling with combining Ctrl+Shift though. The below code works fine with the Esc button. However, when pressing Ctrl+Shift initially (before pressing Esc) it doesn't print anything, while after having pressed Esc at least once, it works for Shift but not for Ctrl- which is not what I intended. How can I bind Ctrl and Shift together?

from pynput import keyboard

COMBINATIONS = [
    { keyboard.Key.shift, keyboard.Key.ctrl },
    { keyboard.Key.esc }
]

# The currently active modifiers
current = set()

def execute():
    print ("Pressed!")

def on_press(key):
    if any([key in COMBO for COMBO in COMBINATIONS]):
        current.add(key)
        if any(all(k in current for k in COMBO) for COMBO in COMBINATIONS):
            execute()

def on_release(key):
    try:
        current.remove(key)
    except KeyError:
        pass

with keyboard.Listener(on_press=on_press, on_release=on_release) as listener:
    listener.join()

Answer 1

If you put a print(key) at the start of on_press, you'll see that the CTRL key generates either a ctrl_l or ctrl_r key (depending on which one you've pressed), not a ctrl key.

So you either have to handle either of them, ending up with some monstrous any/all/any code snippet, or just translate at the top:

if key == keyboard.Key.ctrl_l or key == keyboard.Key.ctrl_r:
    key = keyboard.Key.ctrl

---

A version which handles this with a translation function xlate() (for CTRL and SHIFT keys, since the latter appear to generate shift/shift_r), as well as detecting releases of keys, can be seen below:

from pynput import keyboard

COMBINATIONS = [
    { keyboard.Key.shift, keyboard.Key.ctrl },
    { keyboard.Key.esc }
]

current = set()

def execute():
    print ("Pressed!")

def xlate(key):
    if key == keyboard.Key.ctrl_l or key == keyboard.Key.ctrl_r:
        return keyboard.Key.ctrl
    if key == keyboard.Key.shift_l or key == keyboard.Key.shift_r:
        return keyboard.Key.shift
    return key

def on_release(key):
    key = xlate(key)
    if key in current:
        current.remove(key)

def on_press(key):
    #print(key) # for debugging purposes.
    key = xlate(key)
    if any([key in COMBO for COMBO in COMBINATIONS]):
        current.add(key)
        if any(all(k in current for k in COMBO) for COMBO in COMBINATIONS):
            execute()

with keyboard.Listener(on_press=on_press, on_release=on_release) as listener:
    listener.join()