Head First Python, 3rd Edition by Paul Barry

Author:Paul Barry [Paul Barry]
Language: eng
Format: epub
Publisher: O'Reilly Media, Inc.
Published: 2023-08-25T00:00:00+00:00

Relax

The print dir invocation produced a big list, but you only need to worry about half of it.

You can safely ignore all of the methods which start and end with the double underscore character, such as __add__ and __ne__. These are this object’s “magic methods” and they do serve a purpose, but it’s far too early in your Python journey to worry about what they do and how you can use them. Instead, concentrate on the rest of the methods on this list.

there are no Dumb Questions

Q: If those double-underscore methods are not important, why are they on the list returned by dir?

A: It’s not that they aren’t important, it’s more a case that you don’t need to concern yourself with what they do at this stage. Trust us, when you need to understand what the double-underscore methods do, we’ll tell you. Pinky-promise.

Q: Is there a way I can learn more about what a particular method does?

A: Yes, and we’ll show you how in a page or two. What’s cool is that using Jupyter makes this an especially easy thing to do.

Q: It’s all a bit of a mouthful, all this double-underscore stuff, isn’t it?

A: Yes, it is. Most Python programmers shorten “double_ underscore add double_underscore” to simply “dunder add”. So, if you hear someone refer to an method as “dunder exit”, what they are actually referring to is __exit__. All of these (as a group) are called “the dunders”. Further, any method which starts with a single-underscore is known as a “wonder” (and – yes – it is a perfectly acceptable reaction to groan at all of this).

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