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Python Python Collections (2016, retired 2019) Dictionaries Packing and Unpacking Dictionaries

Vedang Patel
Vedang Patel
7,114 Points

I am really confused with packing and unpacking

I am confused how did you get everything printed I really don't understand the concept of packing and unpacking

3 Answers

150,854 Points

Hi Vedang,

I recommend the following article: http://hangar.runway7.net/python/packing-unpacking-arguments. It concerns the use of the asterisk and double-asterisk (* and **, respectively.) They're used to pack the arguments that a method takes into a tuple. Unpacking allows the programmer to pass packed arguments to different methods.

Uses for packing/unpacking (from the linked article):

"Combined together packing and unpacking lets you do a lot of things like:

  • validate arguments before passing them on
  • set defaults for positional arguments
  • create adaptors for different pieces of code / libraries
  • modify arguments depending on context
  • log calls to methods
  • write better and more resilient wrappers"

Hope this helps!

In my 'real life' I have to do a bunch of string manipulation, so I use lots of regular expressions (ack! hard but very useful) and tuples. As unpacking results in tuples, packing sets up the argument, so it's a natural. I found this article in Stack Overflow very useful: "http://stackoverflow.com/questions/3753589/packing-and-unpacking-variable-length-array-string-using-the-struct-module-in-py" when trying to recall what I'd learned. I hope it's helpful to you :)