2020-11-28 - Keypresses in Python 
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For my work i was building a simple data logger in Python. And the 
first version consisted of a fairly fancy application built using 
the Tkinter and matplotlib libraries. And while this was fun to do, 
i also wanted to create a simpler, more basic version of the logger 
that was independent on any external libraries.

So the fancy GUI and live plotting capabilities were dumped in 
order to write a simple CLI application. I wanted the program to be 
a bit interactive, showing a menu from where datalogging could be 
started. Once the datalogging is started, a keypress should stop 
the logging and return to the main menu.

Funnily enough, i found out vanilla python on Windows is unable to 
detect keypresses without importing some external libary such as 
Pyinput or (Py)Keyboard. I believe on Linux the Curses library is 
built into Python by default, but this is not the case on Windows 
(which is the target for my little script).

As i did not need very fancy keypress handling, i didn't want to 
use an external library just to abort datalogging with a press.

So therefore i opted to catch Python's KeyboardInterrupt and build 
my little program around this as follows:

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import time

def print_menu():
    print("-----------------------------------")
    print("1: Start Recording (Ctrl-C to stop)")
    print("0: Quit")
    print("-----------------------------------")
    c = input("Choice: ")
    if c == '1':
        while 1==1:
            print ("Recording...")
            time.sleep(1)
    elif c=='0':
        exit()

if __name__ == '__main__':
    while 1==1:
        try:
            print_menu()
        except KeyboardInterrupt as e:
            pass           
            e.__traceback__ = None
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So the main program keeps looping to show the print_menu, and once 
the user chooses to start Recording, the Recording loop runs, until 
Ctrl-C is pressed,and the print_menu is shown again.

This works pretty nicely, and this way i can interrupt the logging 
with a keypress (Ctrl-C) without needing an external library.

But as i'm writing this, i am starting to think this program is not 
good practice at all for a proper Unix-way of working. Instead of 
writing the script as outlined above, i should change the program 
to use command line arguments, and use std. in/output.

So instead of an "interactive" program with a menu, the program 
should just start recording directly after it has been started with 
a certain commandline argument. And it should output its data 
directly over stdout. 

This would perhaps be a more unix-like way of doing this, and will 
make it more useful on the commandline. I think it is time to 
re-read "The Art of Unix Programming" by Eric S Raymond again.