PySnooper

Looks interesting I will definitely try this. For those that find this interesting, you might also like pysnooper - I use it all the time. https://github.com/cool-RR/PySnooper https://python.plainenglish.io/pysnooper-stop-debugging-pyth...

Shameless plug: PySnooper is a debugging tool for Python that lets you debug in a way that's as easy as adding print statements, but gives you a lot more information automatically. https://github.com/cool-RR/PySnooper/ HN thread: https://news.ycombinator.com/item?id=19717786

The Python package PySnooper is pretty good for "fancy" print debug statements: https://github.com/cool-RR/pysnooper I've caught quite a few bugs using this show-me-all-locals() approach...

Funny, a few months back I added this sentence to PySnooper's readme: "PySnooper is a poor man's debugger. If you've used Bash, it's like set -x for Python, except it's fancier." https://github.com/cool-RR/PySnooper

I use PySnooper[1] when code behavior deviates inscrutably from my mental model. Like Icecream, PySnooper exhorts, "Never use print for debugging again." A simple example: import pysnooper @pysnooper.snoop() def add_up(numbers): total = 0 for number in numbers: total += number return total add_up([123, 456]) When run, PySnooper prints the activity of the decorated function or method: $ python example.py Source path:... /home/joel/example.py Starting var:.. numbers = [123, 456] 08:46:58.742543 call 4 def add_up(numbers): 08:46:58.742692 line 5 total = 0 New var:....... total = 0 08:46:58.742722 line 6 for number in numbers: New var:....... number = 123 08:46:58.742755 line 7

Nice article. In particular the -i flag seems really useful. I'd like to add two packages I learned about recently that I like A LOT: pyrasite and PySnooper. Use pyrasite to "attach" to an existing running Python process (i.e. you forgot to instrument the app, but it has a bug in it, how can you debug?) (1) Install pyrasite (2) Get the PID of the running process (3) Run `pyrasite <pid> dumpstackz0.py` where dumpstackz0.pycontains `import traceback; traceback.print_stack()` (4) The stacktrace will be printed in the stdout/stderr of the running application Use PySnooper instead of print-debugging—just add a decorator to any python function to get detailed debug info like you normally would get from a full debugger: (A) code: https://github.com/cool-RR/PySnooper (B) pypi: https://pypi.org/project/PySnooper/ (C) talk: https://www.youtube.com/

>I don't understand why you think print or log debugging is inherently bad. I use it myself all the time, but it just shows the weakness of the tooling that people have to resort to such measures. Fortunately, some people are working on it [1]. >Also, it's part of the format string and not a special print function so that it can be used for logs and other output as well, not just the console. Since print (and hypothetical debug_print) are no longer statements like in 2.x, there's nothing preventing them from returning the string that's supposed to be printed. For example print's keyword file is sys.stdout by default. Why not borrow from Common Lisp's format and make it return the string if file=None is passed? Then you could do logging.warning(debug_print('Unusual situation', foo, bar, file=None)) and it would print "WARNING: Unusual situ

Good question. If the function is launched in a spawned process, it'll work, though you might have trouble getting the stderr, so you better include a log file as the first argument, like this `@snoop('/var/log/snoop.log')` If the function launches new processes internally... I'm not sure. If you try it and it doesn't work, open an issue: https://github.com/cool-RR/PySnooper/issues