loveknight

It's currently in its third edition, published November 2024.

ISBN-10: 0-13-817218-8

ISBN-13: 978-0-13-817218-3

I've discovered it (in its second edition) in my local library just yesterday. Even what little I've read so far has significantly improved my understanding, e.g. about decorators.

The testimonials for second edition are really something:

“I have been recommending this book enthusiastically since the first edition appeared in 2015. This new edition, updated and expanded for Python 3, is a treasure trove of practical Python programming wisdom that can benefit pro- grammers of all experience levels.”

—Wes McKinney, Creator of Python Pandas project, Director of Ursa Labs

“If you’re coming from another language, this is your definitive guide to taking full advantage of the unique features Python has to offer. I’ve been working with Python for nearly twenty years and I still learned a bunch of useful tricks, especially around newer features introduced by Python 3. Effective Python is crammed with actionable advice, and really helps define what our community means when they talk about Pythonic code.”

—Simon Willison, Co-creator of Django

“Now that Python 3 has finally become the standard version of Python, it’s already gone through eight minor releases and a lot of new features have been added throughout. Brett Slatkin returns with a second edition of Effective Python with a huge new list of Python idioms and straightforward recommendations, catching up with everything that’s introduced in version 3 all the way through 3.8 that we’ll all want to use as we finally leave Python 2 behind. Early sections lay out an enormous list of tips regarding new Python 3 syntaxes and concepts like string and byte objects, f-strings, assignment expressions (and their special nickname you might not know), and catch-all unpacking of tuples. Later sections take on bigger subjects, all of which are packed with things I either didn’t know or which I’m always trying to teach to others, including ‘Metaclasses and Attributes’ (good advice includes ‘Prefer Class Decorators over Metaclasses’ and also introduces a new magic method ‘init_subclass()’ I wasn’t familiar with), ‘Concurrency’ (favorite advice: ‘Use Threads for Blocking I/O, but not Parallelism,’ but it also covers asyncio and coroutines correctly) and ‘Robustness and Performance’ (advice given: ‘Profile before Optimizing’). It’s a joy to go through each section as everything I read is terrific best practice information smartly stated, and I’m considering quoting from this book in the future as it has such great advice all throughout. This is the definite winner for the ‘if you only read one Python book this year...’ contest. —Mike Bayer, Creator of SQLAlchemy

More testimonials are available under the link above.

Book website: https://effectivepython.com/ (Don't buy from Amazon, of course.)

If you're like me and prefer printed books, look up the ISBN at euro-book (which also offers portals for Brasil, Mexico and the USA) to find any affordable used copies.

This is a little tutorial that I found in my search to learn how to use getopt (mind: not getopts, which is a completely different thing). I want to share it here because I find it refreshingly to the point. Just the main code block already tells almost the whole story:

#!/bin/bash
# Set some default values:
ALPHA=unset
BETA=unset
CHARLIE=unset
DELTA=unset

usage()
{
  echo "Usage: alphabet [ -a | --alpha ] [ -b | --beta ]
                        [ -c | --charlie CHARLIE ] 
                        [ -d | --delta   DELTA   ] filename(s)"
  exit 2
}

PARSED_ARGUMENTS=$(getopt -a -n alphabet -o abc:d: --long alpha,bravo,charlie:,delta: -- "$@")
VALID_ARGUMENTS=$?
if [ "$VALID_ARGUMENTS" != "0" ]; then
  usage
fi

echo "PARSED_ARGUMENTS is $PARSED_ARGUMENTS"
eval set -- "$PARSED_ARGUMENTS"
while :
do
  case "$1" in
    -a | --alpha)   ALPHA=1      ; shift   ;;
    -b | --beta)    BETA=1       ; shift   ;;
    -c | --charlie) CHARLIE="$2" ; shift 2 ;;
    -d | --delta)   DELTA="$2"   ; shift 2 ;;
    # -- means the end of the arguments; drop this, and break out of the while loop
    --) shift; break ;;
    # If invalid options were passed, then getopt should have reported an error,
    # which we checked as VALID_ARGUMENTS when getopt was called...
    *) echo "Unexpected option: $1 - this should not happen."
       usage ;;
  esac
done

echo "ALPHA   : $ALPHA"
echo "BETA    : $BETA "
echo "CHARLIE : $CHARLIE"
echo "DELTA   : $DELTA"
echo "Parameters remaining are: $@"

Just be sure to correct the inadvertent mixing of beta and bravo.

Edit: I figured it out: The solution is over a process substitution operator:

join <(echo "$var1") <(echo "$var2")

See also the comment by @notabot@piefed.social below, this StackOverflow comment, and the GNU documentation..

It's comparatively straightforward to use the content of one variable in join by using - to tell it to use standard input for that file:

echo $variable | join - anotherfile

However, is there a way to serve both input 'files' from variables, avoiding temporary files on the disk?

It seems like the easiest way would be via creating and mounting a temporary partition via tmpfs,

mount -t tmpfs -o size=50m tmpfs /mountpoint,

and just create temporary files in there. And afterwards clean things up.

So far I've also attempted here-documents, but apparently this too can only provide standard input, so that the other input still has to be served from a file.

Maybe one can also try doing it via named pipes (mkfifo), but I fear this could introduce lots of potentialities for errors.

Let me show you what I mean by giving an example:

# Assume we have this list of increasing numbers
140
141
145
180
190
...

# If we pick 150 as threshold, the output should consist of 145 and all larger values:
145
180
190
...

# In the edge case where 150 itself is in the list, the output should start with 150:
150
180
190
...

I guess one can always hack something together in awk with one or two track-keeper variables and a bit of control logic. However, is there a nicer way to do this, by using some nifty combination of simpler filters or awk functionalities?

One way would be to search for the line number n of the first entry larger than the threshold, and then print all lines starting with n-1. What command would be best suited for that?

Still, I'm also wondering: Can awk or any other standard tool do something like "for deciding whether to print this line, look at the next line"?

(In my use case, the list is short, so performance is not an issue, but maybe let's pretend that it were. Also, in my use case, all entries are unique, but feel free to work without this assumption.)

When I'm editing with helix, I often have multiple instances of it running, one for each file, in different terminals (more precisely: in different tabs of my terminal emulator, Konsole). Currently, the title of these tabs reads just "Directoryname: helix". It would be really helpful if the titles included the current filename, so that I could see which tab has which file opened. Is there a way to do this?

ISBN: 9780596005955

This book is extremely readable and gives a very good introduction to the various standard Unix shell commands (grep, sed, awk, tr, sort to name but a few) and how to tie them together to do useful things. It's very suitable if you have some experience with the command line at the level of individual commands but now want to see how to do construct more interesting pipelines and scripts. It includes an introduction to regular expressions. The fact that the book is already 20 years certainly means that some explanations and approaches are outdated, but since shell programming is at the core about text processing, almost all contents of the book are still highly relevant today.

Things I would like every young web engineer to learn:

• anything you can do in CSS + HTML, you should do in CSS + HTML
• framework du jour is not a platform, it's a high-interest loan against your future capacity. The platform is the platform
• understanding the memory hierarchy always matters
• client-side isn't easier than the server, and "generalists" usually suck at client-side. Mind the (packet) gap
• managers who are not technical are not useful
• put users first, always

Second-order things to learn:

• the way browsers work isn't static, but it also isn't changing that fast. Learn as much as you can and update every few years; particularly about networking and the rendering loop.
• JS is the slowest way to do anything on the web. Never let it become the way you do everything.
• a11y isn't nice-to-have, it's the job
• shipping fast almost never matters as much as quality, & there are simple heuristics you can use to understand the difference