5 Useful Python Decorators (ft. Carberra)

Here are 5 useful decorators that can help make your code more convenient to use! And a big thanks @Carberra for joining in on this video; do check him out if you love Python!

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00:00 Learning Python made simple
00:05 Intro
00:32 @retry
02:42 Sponsor
02:52 @cache
05:50 @get_time
07:51 @deprecated
10:58 @on_exit
13:51 Amazing

[anamoyeee]

Congratulations on getting the sponsorship deal!

[wrichik_basu]

Very nice collab! The deprecated decorator was a very much necessary functionality, especially for libraries. Coming from a Java background, not having this decorator in the main Python language surprised me.

[finnthirud]

atexit: Doug Hellmann's book about the Python 3 standard library pages 995-997 mentions three conditions when atexit will not be invoked: 1) the program dies because of a signal, 2) os._exit() is invoked directly, and 3) a fatal error is detected in the interpreter.

[SuperVirus]

When it comes to retries, you may want to have a look at the Tenacity library.
E.g. Tenacity allows for random wait times, exponential wait times or even only retrying for certain exception types.

[AntonioZL]

One of the best uses of the cache decorator is in recursive functions. Every recursive call get's cached, meaning if you call factorial(n) and then factorial(n+2), only 2 extra recursive calls will be made, for a total of n+2 calls. Any call to factorial(m) for m =< n will also be entirely cached.

[IceArdor]

Tenacity’s retry decorator is really good and quite expressive.

Atexit: use a context manager with a try/finally block to close that database for most applications. Atexit mainly applies to long running python programs that are run as a server or daemon.

[auroragb]

I've also written the retry and the timing decorators a few times for various projects, I wish it were standardized in a built-in module

[pldvs]

Some code that might be useful to my project, a source that looks well worthy of a sub, and a literal belly laugh. Thanks for that mate.

[workingguy]

Once I finish a project that I'm working on I'll watch a lot of your videos and try to apply some new learnings to my old python projects, really informative things you're pushing out

[juancharlie]

Simply the best videos for people learning Python. You're a highly effective communicator who has a teaching spirit. Thank you for helping!

[dcollett]

These are excellent (as are ALL of your videos). Thank you! 😺

[samrat]

You can also use lru_cache instead of cache, it will automatically remove the cache which is not used recently.

[chair]

Probably one of the coolest things I ever created that I unfortunately no longer have was a decorator that would turn a function into a tkinter form automatically.

[texloch]

Love your videos man! Super helpful towards improving my coding practices

[michaelhoffmann]

A fun follow up video would be a brief overview on how to create your own decorators! I've done so, for some client specific code and it's a fun exercise 😁

[mohamedahmed]

this was reallly helpfull, i was struggling to write this to evevry function i use to measure time or apply retry functionalliy

[pavfrang]

Thanks for the great video!

Obviously you know it, I prefer one-liners for these:
sum(1 for letter in text if letter in vowels)

[Kommentierer]

I like to add a filter for exception types when writing a retry decorator. When fetching some stuff, it might fail due to connection issues or a rate limiting. Then it is fine to retry it. But if you parse or transform the result in the same function, it will fail always if something is different than expected, so usually no need to retry it.
And, my favourite case, if you cause a KeyboardInterrupt at the same time, would it retry it as well?

[brunocunha]

Excelent content, thanks for sharing it (:

For those thinking about counting vowels in a str, the version below has time complexity of O(n)

```python
def count_vowels(input_str: str) -> int:
vowels = 'aeiouAEIOU'
return sum(1 for char in input_str if char in vowels)
```

[deadeyea]

Instead of own retry decorator, use backoff. It's also compatible with asyncio. But it's an additional dependency.