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pythonkeyboard
Gary I
Gary I

Reputation: 55

Detecting keyboard input

I'm pretty new to Python and I am trying to detect when the f key is pressed using the keyboard library. This is the code I am trying to run

import keyboard

keyboard.on_press_key('f',here())

def here():
    print('a')

However when specifying here() as the callback, I get a name not defined error on building

Upvotes: 3

Views: 15221

Answers (3)

MarcusDev
MarcusDev

Reputation: 54

import keyboard
IsPressed = False

# once you press the button('f') the function happens once
# when you release the button('f') the loop resets

def here():
    print('a')

while True:
    if not keyboard.is_pressed('f'):
        IsPressed = False
    while not IsPressed:
        if keyboard.is_pressed('f'):
            here()
            IsPressed = True

# or if you want to detect every frame it loops then:

def here():
    print('a')

while True:
    if keyboard.is_pressed('f'):
        here()

Upvotes: 1

iz_
iz_

Reputation: 16633

When you are calling here(), it is not defined yet, so move the declaration of here() above your code.

Also, because here is supposed to be the callback, you need to pass it to on_press_key as a function reference.

import keyboard

def here():
    print('a')

keyboard.on_press_key('f', here)

Upvotes: 3

Raoslaw Szamszur
Raoslaw Szamszur

Reputation: 1740

Just move up you function here() declaration like so:

import keyboard

def here():
    print('a')

keyboard.on_press_key('f', here())

otherwise here() is not yet declared hence your error.

NameError: global name '---' is not defined Python knows the purposes of certain names (such as names of built-in functions like print). Other names are defined within the program (such as variables). If Python encounters a name that it doesn't recognize, you'll probably get this error. Some common causes of this error include:

Forgetting to give a variable a value before using it in another statement Misspelling the name of a built-in function (e.g., typing "inpit" instead of "input")

For python interpreter in your case when it's on line:

keyboard.on_press_key('f',here())

it doesn't know what here() is because it's not yet in memory.

Example:

$ cat test.py 
dummy_call()

def dummy_call():
    print("Foo bar")
$ python test.py 
Traceback (most recent call last):
  File "test.py", line 1, in <module>
    dummy_call()
NameError: name 'dummy_call' is not defined



$ cat test.py 
def dummy_call():
    print("Foo bar")

dummy_call()
$ python test.py 
Foo bar

Upvotes: 1

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