Understanding python *args and **kwargs (opens in new tab)

Google? Honestly, I just took what I assumed was going to be a plunge back into Python for web development (preferred lang is Ruby). I opted to relearn Python because Google has a visible preference for it. After a 24 hour refresher (reading Guido's documentation), I am pleasantly surprised. Who knew Python actually has some strong things going for it? ;)

> I wonder what's driving it.

Just some guesses/thinking-out-loud:

* people are getting sick of php (well, sicker than usual)

* Python 3 has been out for a while and it's starting to be used by more people

* Perl 6 is seeing regular releases, some tutorial material is showing up out there, so maybe it's having an effect of getting people interested in new languages

* It's possible that some Rubyists who left the ship are now returning.

Because there're unqualified hackers here.

The number of upvotes such a content-lite article gets on HN is interesting, and maybe an indicator of a changing demographic here.

What's next? a few pages on Ruby's method_missing? :-)

5 minutes followed by a sweet aha! moment.

What the article seems to miss, though (only skimmed it), is that you need to be incredibly careful with taking kwargs, specially if you're passing them along into secondary functions within the called function. Hidden bugs lie that way, as you could end up with bad/misspelled args that you think are having an effect, but aren't.

Always make sure all kwargs get unpacked.

It's also covered in the official Python tutorial.

No kidding.

  A much, much more simple way to put it is 
  anything *args is a list, anything  **kwargs is 
  a dictionary.

  The * simply means list (set). 
  ** simply means dictionary (name/value pairs)

  * and ** has a much different meaning in other 
  languages as parameters.

  * args is very similar to ... in other languages 
  that let you send n arguments.