I found this site fantastic for improving my RegEx skills - https://regexcrossword.com/. Most people find solving puzzles more fun than reading text books, and the hands-on experience / forcing you to think rather than just read, can really help things stick in your memory.

This always helps me in learning and debugging regex: https://regex101.com/

Haven't done the Regex course, but Gary Bernhardt's https://www.executeprogram.com looks promising and haven't seen it mentioned

Can you really learn regex in one hour? I learned them so long time ago and in a gradual way that I have no idea how long it would take if you focus on it, but I feel like it would be more than an hour since I think most people would need to play around quite a bit to really grasp them.

There is a way of thinking when you deal with regexes that took me a while to get.

Reading the first chapter of ORiley's Mastering Regular Expressions was what made me get it and that was maybe an hours worth of time.

Yes, regular expression. Saves me from lines of substr, split, join, etc.

Eh, I always use substr, split and so on if possible. They make the code way easier to read than with a regex.

It really depends on what you're doing, and at least being aware of what regex can do will help with deciding which is better for a given situation.

For example, I remember once replacing a buggy 3-4 lines of python based on split/etc with a single regex: match all \d+ (it was for extracting IDs from a user-input string)

Simple transformations can easily become complex to do with regex, so I've started using vim macros instead.

Regex don’t do transformations? All they can do is match strings.

If I have a list of names I’d like to reverse:

John Smith > Smith, John Anna Peterson > Peterson, Anna

I can write:

(.) (.)

And replace with:

\2, \1

Not sure if that’s part of some “official” regex spec but it works more or less everywhere.

(Of course if it was an actual list of names I’d have to be a lot more intelligent with double names etc.)

Almost. All regular expressions do is match strings and find the starts and ends of whole matches and match groups. And this is an important distinction since match group support adds quite a bit of complexity to the theory behind regular expressions and also increases their usefulness by quite a bit.

Regular expression libraries then often can use these boundaries, for the whole match and for groups, for transform the string (e.g. replacing what was matched by a group with some other content).

Regex grouping expressions along with find & replace enable transformations.

agree...regular expression is like magic to me

I spent an hour learning the basics - wildcards, whitespace, escape symbols and Character ranges are enough for them to be useful.