Learning Perl, Intermediate Perl, Modern Perl, Perl Testing: A Developer's Notebook, Programming Perl (the Camel book), Mastering Perl, Higher Order Perl, Advanced Perl Programming, 2nd Ed (old, but pretty good), Mastering Algorithms with Perl (also old but excellent), Effective Perl Programming, Programming the Perl DBI, Object Oriented Perl (conway - Oldie but goody), Perl Best Practices (conway), Perl Template Toolkit...

But those are all Perl focused books. You can also learn a lot by going outside the echo chamber to look at other languages and at cross cutting concerns; the G4 Design Patterns book, a book or two about building microservices, some SQL and database books, some books around other languages like the C++ Primer (not "Plus"), a C book, SICP (the Scheme book), some JavaScript books, a Python book, a Go book, and so on. Also books on supportive technology: the OReilly Git book (can't remember the name offhand, 2nd edition or later, though), or the open source Git book, the OReilly Vim book, a Bash book.

That right there represents years of reading materials. Also read the Perl POD (all of it ... ok, you can skip a little of it but most of it). Also the POD for most common CPAN modules. Perl blogs, and even the Perl language source code (good luck though, it's rough).

What Discipulus and davido said. I found the Perl Cookbook extremely eye-opening because it’s not theoretical, it’s task oriented. That said, it’s verrrrrrrry out of date so should be taken as a leg up on modern approaches enabled by the CPAN and newer Perls.

The best penny-dropper for me is reading tests. Most distributions have a test directory called t. On metacpan.org you can search and visit a module/package of interest, click on Browse, navigate to the top of the the package ({USER/PACKAGE-VERSION} formatted name currently), click on t, and read tests. Download and decompress to play around, edit, and run yourself with prove.

I knew I was leaving something important out: the Perl Cookbook, it's old, but also opens ones eyes to the Perl way (although it really is getting a little long in the tooth).




Dave

Do not worry about Perl Cookbook being 'out-of-date'. It is often possible (but never necessary) to spice up a recipe with a dash of modern perl.
Bill

I agree in spirit, mostly. In that same spirit, it’s also possible to write complex web applications with cgi-lib.pl. :P The Perl Cookbook is 21 years old and best practices have changed radically; Perl 5.4(!) was still new at the time. There is a lot of code in the book that I would be angry to find in production today.

Don't forget to visit the Book Reviews right here in the Monastery.

in the O'Reilly serie there are a lot of other good books: they all are worth to read: I have a particular love for an old one: Perl Cookbook.

See also ModernPerl book (free) and some links at learning and teaching Perl

L*

Great suggestions so far, so I want to throw in one of the most important books for my own personal Perl growth, Learning Perl Objects, References and Modules by Randal Schwartz and Tom Phoenix.

I also can't say enough about what Your Mother said regarding the reading of CPAN distribution test files.

Although much of the time the author will write code in ways that kind of defy the logic of standard practices (ie./eg. I write a lot of my tests to be short to the point that brevity is above all else), it's a fantastic way to identify what the author meant by the use of the software the tests are running against.

You can compare test elements to the code within the actual modules, and to further knowledge, practice by writing additional tests where you feel the original authors may not have thought about certain edge cases. If desired, you could even have the author add these new tests.

Learning Perl Objects, References and Modules was the 1st Edition of what is now known as Intermediate Perl. The name change introduced a broader range of topics not covered in the original, while also making the book easier to market.




Dave

Intermediate Perl Covers several topics (Especially preparing a module for release) not seen anywhere else in the series and it does include exercises for each chapter. Unfortunately, it falls far short of the quality I have come to expect from O'Riley books. I have discovered two examples which do not work as advertised because of bugs in CPAN modules which they use. These examples could not have been tested (certainly not under windows).
Bill

Heh, I honestly don't recall that at all. Thanks for clarifying David!

I've kept a (long) list of Perl books questions here.