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Randal Schwartz's Perls of Wisdom
Perls of Wisdom is a collection of 65 selected columns from Linux Magazine, Unix Review, and the now-defunct Web Techniques magazines, written between May 1995 and July 2004. In each column, Randal discusses some problem that he had to solve, or that someone else needed help in solving. He carefully discusses the problem, and then shows the Perl code needed to resolve it. Many of the columns are complete applications that can be run (with minor modifications) by the reader. (The listings are also available from the apress.com web site.) Each column has been reproduced as it was written in the original magazine, with "Randal's Note" prepended. Therein lies this book's best feature and greatest flaw. Allow me to explain.
When I first picked up this book, I had only read a couple of Randal's columns (from Web Techniques), and saw that he wrote tutorials of proper Perl usage. He also relies on the wealth of modules submitted to CPAN to leverage a solution. After all, why reinvent the wheel? I expected to see more commentary on the reasons behind choosing one solution over another, or insights into the inner workings of Perl itself. I more or less got what I expected. For example, the first column reproduced in the book (It's All About Context) explains why, when someone used my ($f) = 'fortune'; instead of my $f = 'fortune'; he got in trouble with the law (see the book to understand the legal issue). The first form only retrieves the first line of the output of the fortune program, while the second form retrieves the entire output. Little items such as scalar versus list context can trip many Perl coders.
The first chapter (Advanced Perl Techniques) does give you many tips and insights like the example I just gave. All but two of the twenty columns are little tutorials on the ins and outs of handling the commonplace day-to-day issues that Perl can address with ease. Some delve into more obscure topics, such as the difference between shallow and deep copies of structures, and Perl's Taint mode. Two columns contain complete programs. One extracts the text from the man pages and determines their "fog" index (a measure of readability). The other creates a mirror of files needed by CPAN.pm to install new modules. For each program, Randal gives the entire listing as well as an almost line-by-line description of how it works. Each column is written in a conversational style that is easy to read, yet doesn't talk down to you.
The following chapter is comprised of seven tutorials on the various aspects of searching, sorting, and formatting text. In addition to describing the creation and compilation of regular expressions, Randal also discusses formatting and the nifty "Schwartzian Transform" (Perl's map-sort-map idiom for sorting on almost anything) which was named for him, but not by him. While some of the information is a little long-in-the-tooth (the column on Text-Processing was written shortly after Perl 5 was released), it's all interesting and educational nonetheless.
Chapter 3 starts refocusing the use of Perl to web sites. This chapter discusses HTML and XML processing in six little columns. He shows how to generate a web page index, producing a web page calendar from a file of events, and parsing XML to retrieve the data within. He also includes a lesson on how to use Perl to compare two arrays to create an HTML-formatted difference table.
The next chapter demonstrates that Randal has spent a lot of time working out ways to update and improve his web site. It covers the intricacies of CGI programming in Perl. All but one of the fifteen columns are complete programs (again, available from apress.com) with line-by-line commentary. The programs do implement mostly worthwhile functionality, but each column was pretty much "I had this problem, so I wrote this program. Lines 1-3 do this; lines 4-5 do that, etc." Granted, some of the programs are pretty nifty (check out how he automatically keeps track of the "What's New?" pages), but the reading of one program after another started to become stale.
The final chapter is titled "The Webmaster's Toolkit," consisting of fourteen programs and three tutorials. Randal covers diverse web server background topics such as creating a light-weight load balancer, random links, and forcing users to enter through the "front door." There are also instructive techniques for throttling your web server's usage of the processor (a necessity at the time for Randal, as his web site was co-resident on a server with others), and calculating download times.
In its entirety, Perls of Wisdom contains 65 columns, split roughly half-and-half between tutorials and fully commented programs. More than half of the columns show that Randal uses Perl for web processing more than for general scripting, data reduction and reporting. His tutorial articles are top-notch, but I have a quibble over his program articles, which are somewhat dated. There were a number of prefaced notes to the effect that today he'd do it differently with some new feature or CPAN module. I really wish he had actually updated the column to show the new coding techniques. The original code is interesting in the historical sense, but I wanted to see nuggets of Perl wisdom for me to use in my daily job. The writing style is fine; the bits of insight are useful, but many of the programs are too specific to problems you or I may never see, and were solved in code that's showing its age. I'm glad I got to read the book, but I think it only rates a 7 out of 10.
You can purchase Randal Schwartz's Perls of Wisdom from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
I first learn Perl with the aim of creating dynamics webpages. I learnt from the tutorial Picking Up Perl - this is great and taught my most I needed to know with regard to the language - but it didn't teach me how to use it for websites.
I picked up from code lying about how to read and write files, get post/get data, and so forth, and slowly built up into quite a good Perl programmer (I suppose. Not amazing, but quite fluent). This wasn't easy though and was slow. Why? I never got taught, all in one place, how to do that. I think this is what this book is trying to do - but with a much wider range than just CGI programs (although it doesn't seem to neglect it, either).
I tried to write my own tutorial for using Perl in webpages to try and help. I'm not going to link to it here though, because it is quite terrible (I was 14 when I wrote it).
After learning Perl, and being able to use it, there is always using the standard librarys. For this, PerlDoc has been so helpful to me.
- Jax
Since there wasn't a link to Randal's collection of articles I'm providing one here. There's some excellent stuff in there.
Slashdot: Failed Car Analogies. Amateur Lawyering. Anecdote Battles.
For those trying to follow along but not able to immediately expand the acronym, TIMTOWTDI is There Is More Than One Way To Do It.
500GB of disk, 5TB of transfer, $5.95/mo
For anyone getting into perl I can not recomend The Perl Monks Monastery enough. Lurk for a while, use super search to find the answers to almost any perl question you may have and if all else fails post to Seakers Of Perl Wisdom and enlightenment shall surely follow.
Randal is a regular contributor there and many of the other leading lights of perl pop up frequently.
Regards,
A monk.
Maybe you live in interesting times
Randal Schwartz's Perls of Wisdom will never take the place in my heart that is forever occupied by Steve Litt's PERLS of Wisdom!
In this world nothing is certain but death, taxes and flawed car analogies.
For example, the first column reproduced in the book (It's All About Context) explains why, when someone used my ($f) = 'fortune'; instead of my $f = 'fortune'; he got in trouble with the law (see the book to understand the legal issue)
In the example above, the single quotes should be backquotes instead.
my $f = 'fortune'; will just assign the string "fortune" to $f. This is what the article has, and it's wrong.
my $f=`fortune`; will run a program called "fortune", and assign it's output to $f.
my ($f)=`fortune`; will assign the first line of the output of the fortune program to $f.
Randal also discusses formatting and the nifty "Schwartzian Transform" (Perl's map-sort-map idiom for sorting on almost anything) which was named for him, but not by him.
This is one of the things that's always annoyed me about Perl and its practitioners (well, most programmers, really)...
Given the long history of functional programming (hell, Lisp is closing in on 50 years old), this map/sort/map idiom had to be second nature to any Lisp/Scheme/Haskell/ML/etc. programmer at the time Schwartz wrote about it back in 1996[1]. And the fact that this was such a revelation to the people who read his column that they named the idiom after him just exposes the lack of a diverse programming background for most people. I'm guessing that 50% of the coders out there wouldn't know a map or a fold if it bit them on the ass, and even more wouldn't have a clue as to how to solve something so basic as the missionaries and cannibals problem in a declarative/logical manner (without the help of Dr. Google that is).
Meh... Bitter rant over, I guess...
[1] I could be wrong, I didn't really do much coding before 1995-ish.
-30-
It's not an acronym or a retro-nym. It's a name, Perl. It started as Gloria (after his wife) before it was released, then it was Pearl, then he released it as Perl.
In the old days people spelled it in all caps, i.e. PERL, which was probably due to the fact that people (including Larry) like to pretend it stands for something. I am not aware of any O'Reilly books that refer to it as PERL, they all list it as Perl.
The most common acronym attributed to it is "Practical Reporting And Extraction Language."
(You'll note that actually spells PEARL, a hint of its early name.)
If all is right with the world, Tom Christiansen will flame me unmercifully with everything I got wrong in the preceding story.
JASP - Just Another Slashdot Poster
Ironically, the word ironically is often used incorrectly.
The most common acronym attributed to it is "Practical Reporting And Extraction Language."
(You'll note that actually spells PEARL, a hint of its early name.)
Who needs Tom C., I'll just flame myself.
Actually it spells PRAEL. Duh, I got the wording twisted, it's obviously Practical Extraction and Reporting Language.
Also, I am wrong about the use of PERL on O'Reilly books. I am surprised to see the PERL in a Nutshell title from O'Reilly.
And as a twist on the theme, the pink camel book actually is called "Programming perl," with "perl" in all lowercase.
Ironically, the word ironically is often used incorrectly.
False quote. Wheee.
Read more about the issue here.
A list of names is also useful: material by Damian Conway, Larry Wall, Randal Schwartz, Mark Jason Dominus, Simon Cozens (Perl involvement now minimal due to career change), and persons associated with them is going to be top notch. Plug their names into Google and see what they have to say. Catch a presentation or read a book by one of them if you can. Meanwhile, there is truly a lot of junk out there. There's an article out there somewhere about "how to tell a good Perl book from a bad Perl book," which I thought was by Mark Jason Dominus, but I can't seem to find it at the moment.
Finally, 90% of the useful modules you'll see recommended for use from CPAN are written by the intelligent lights in the Perl community. The time-tested modules that are now standard solutions are those that were written with high quality by good programmers.
Secession is the right of all sentient beings.
What's the difference between "perl" and "Perl"?
One bit.
Oh, you weren't talking ASCII? :-) Larry now uses "Perl" to
signify the language proper and "perl" the implementation of it, i.e.
the current interpreter. Hence Tom's quip that "Nothing but perl can
parse Perl." You may or may not choose to follow this usage. For
example, parallelism means "awk and perl" and "Python and Perl" look
OK, while "awk and Perl" and "Python and perl" do not. But never write
"PERL", because perl is not an acronym, apocryphal folklore and post-
facto expansions notwithstanding.
Stop intellectual property from infringing on me
> I agree there is a problem in the community with stuff like this.
> Personally, I tend to ignore the community and just use the language the way I feel it's best used.
I started getting into Perl about 5 yrs ago and subscribed to comp.lang.perl.misc
I have never come across a newsgroup inhabited by so many arseholes.
The flaming of newbies was encouraged and posting obfuscated code par for the course. There was an overwhelming sense of how many Perl programmers thought themselves a cut above everybody else; full of people who would handily put obfuscated Perl in their sigs so that you could straightaway identify them as:
(a) A language snob.
(b) A fucktard.
I unsubscribed from the group but persisted with Perl. For me, Perl fills the gap between shell scripts and pukka standalone apps (it's even pretty easy to GUIfy a script with Tk).
I found the best resources to be the Camel book and Cookbook from O'Reilly.
I bet a lot of people got put off Perl by that group at that time - God curse their black souls! It was a shame because there were some good contributions on the group from people like Randal.
The Machine stops.
Well..... technically he got kicked out because he launched into an asinine rage about the service charge on his debit card. Also, about some coffe candies which has a mismarked price of ".03 Cents". Oh, and 'false advertising', and the coffee shop being 'the worst business in Portland'. (Comical due to the "Small Business of the Year" award just behind the cash register.) [But I don't really want to get all technical.]
"A complex list comprehension can lead to some powerful code that does an amazing amount of stuff in a neat little package. To me this is different than the arbitrary line-noise you get with Perl."
There you just lost me. The term "line noise" implies a low signal-to-noise ratio, when in fact Perl presents exactly the opposite. The SIGNAL is in fact, so high that many programmers find it difficult to cope with. That's fine, but let's not confuse that with actuall NOISE.
"So Perl 6 lets you define your own syntax so that someone reading your code neads to figure out what your ideas of the Right Language is?"
No. You wholy misunderstood the concept.
In Perl 6, you will have full access to the grammar, so you could enforce your local stylistic conventions. You would obviously not want to make INCOMPATIBLE changes so that your code is still valid Perl, but you could write your own "strict".
Think of it this way. Imagine a C++ header that caused all uses of operator overloading outside of a limited few "neccessary" to be illegal, or that issued a compiler warning on every use of an iterator initialization outside of a for loop. These are just simple (and not very useful) examples, but they serve to illustrate the point: you can instrument the compiler just as fully as you can instrument your code. Don't like the type checking in Perl 6? Make it stricter.
I'm sure that there will be someone who will publish the "python-like bondage" module 15 minutes after Perl 6 is released. If you're into that sort of thing, then your company can take full advantage of it, while still getting all the value of Perl 6 like LISP-style currying and macros, Ruby-style mixins, cross-langauge bindings through Parrot, boxed and unboxed type constraints on standard Perl scalars, full multi-method dispatch, etc., etc.
"Common LISP and Scheme's macro facilities can be used to define your own language constructs"
Yes, but we're not talking about defining language constructs. We're talking about changing the behavior of the compiler in structured, standardized ways that aren't just implementation hacks. Don't get me wrong. Common LISP is on my list of cool languages to learn more about right below Python and Ruby. I'm just saying that these particular Perl 6 features bear a bit more looking at.
"Or hell, TeX lets you redefine the world if you are so twisted, though to me TeX is more unreadable than Perl."
TeX is actually a good example of what I'm talking about. TeX is very readable for a full typesetting system, but most of us could not care less about typesetting. When you need to do specific tasks that INVOLVE typesetting, but you don't really need all of that power and flexibility, you step up a layer of abstraction and turn TeX into LaTeX. LaTeX is valid TeX, so it's not quite the same, but the idea of limiting a powerful system in order to step back a level of abstraction holds.
Perl 6 will provide all of the power that you need from a modern high-level programming langauge, but let you manage that complexity. You might decide, for example, to restrict Perl 6 in your programs to just the facilities that make sense for scientific calculation. You might even introduce a special syntax/grammar for putting differential equations directly into your program without having to quote around them and hand them off to a seperate processing tool (object, module, what-have-you).
None of this is useful for your average 1000-line CGI program, but for the company that produces tens to millions of lines of structured libraries upon which new software is built and re-factored over time, this will all be a godsend.
Much of what Perl 6 brings to the table, Common LISP has done for years, but some of it is either gathered from other, more recent langauges (e.g. Python, Ruby, Scheme, Java, etc.) or is, as far as I can tell, unique. I hope you give it a try and throw away your naive ideas of "line noise" in favor of considering the value to your productivity and the maintainability of your code base.