In 30+/-years at $work(EE doing realtime software), I found that if I got the data structures correct, the code usually flowed. If not, things got messy fast. Also, read all the code you can from acknowledged Perl experts(for me in the early days this was reading the Data General RDOS and AOS operating system code).

Domain knowledge is as important as Perl knowledge(You want to control a power system give me a call, develop a website not your man).

James

> I found that if I got the data structures correct, the code usually flowed. If not, things got messy fast.

This reminds me of some famous quotes from Fred Brooks, Rob Pike, Eric S. Raymond, and Linus Torvalds:

The programmer at wit's end for lack of space can often do best by disentangling himself from his code, rearing back, and contemplating his data. Representation is the essence of programming.

-- from The Mythical Man Month by Fred Brooks

Data dominates. If you've chosen the right data structures and organized things well, the algorithms will almost always be self-evident. Data structures, not algorithms, are central to programming.

-- Rob Pike

Show me your code and conceal your data structures, and I shall continue to be mystified. Show me your data structures, and I won't usually need your code; it'll be obvious.

-- Eric S. Raymond

I will, in fact, claim that the difference between a bad programmer and a good one is whether he considers his code or his data structures more important. Bad programmers worry about the code. Good programmers worry about data structures and their relationships.

-- Linus Torvalds

Perl Data Structure References

• perldsc - Perl Data Structures Cookbook
• perlreftut - Perl References Tutorial
• perlref - Perl References
• perldata - Perl Data Types
• perlvar - Perl predefined variables
• perllol - Arrays of arrays in Perl
• perlobj - Perl objects
• Storable - Persistence for Perl Data Structures
• Tie::Hash - base class definitions for tied hashes
• YAML - YAML Ain't Markup Language
• JSON - JSON (JavaScript Object Notation) encoder/decoder
• JSON::MaybeXS - Use Cpanel::JSON::XS with a fallback to JSON::XS and JSON::PP
• TOML - Parser for Tom's Obvious, Minimal Language
• TOML Spec (github)
• Sereal - Fast, compact, powerful binary (de-)serialization
• SerealX::Store - Sereal based persistence for Perl data structures
• Config::Any - Load configuration from different file formats, transparently
• Config::Tiny - Read/Write .ini style files with as little code as possible
• Config::INI - simple .ini-file format
• SQLite (wikipedia)
• DBI and one of the many DBD::* modules
• DBD::SQLite
• Data::Dumper - stringified perl data structures, suitable for both printing and eval
• Data::Dump - Pretty printing of data structures
• App::FatPacker
• Re: How to make distribution for simple script with CPAN dependencies? by 1nickt (2024)
• Re: access object values by kcott (2023) - displaying/debugging Perl data structures and references
• Re: Why can't some of my modules do log output to a file? by haukex (2022) - example of turning on Data::Dumper's Useqq option
• Memory efficient way to deal with really large arrays? by sectokia (2020)
• Re: Memory efficient way to deal with really large arrays? by Tux (2020) - Perl benchmarked faster than every database tried (SQLite, Pg, mysql, MariaDB)
• Re^2: A good way to input data into a script w/o an SQL database by ObiPanda (2023) - asking about code vs data in a script
• How can I send a "transposed slice" of an array of hashes and by extension an array of arrays, or hash of hashes to a subroutine by ObiPanda (2023) - ... continued
• using TIEHASH as wrapper/proxy, while avoiding recursion and warnings by LanX (2024) - using Tie::Hash as a temporary wrapper
• Modules as configuration files by Discipulus (2015)
• Preserve the order in JSON by user786 (2015)

Perl 4 multidimensional array emulation:

• perlvar - if you refer to a hash element as $foo{$a,$b,$c} it really means $foo{join($;, $a, $b, $c)} ... where $; is the subscript separator for multidimensional array emulation aka $SUBSUP (default \034), borrowed from awk
• feature - note that Perl 5.34+ allows you to disable this old Perl 4 multidimensional array emulation via the 'multidimensional' feature
• perl 5.36 delta - ... and that use v5.36; disables multidimensional array emulation
• Whats new in Perl (youtube) by Ricardo Signes (TPC 2021) uses What is this madness? to describe this unfortunate multidimensional mis-feature :-)
• Multidimensional arrays by Bod (2023) - asking for advice on which Perl data structure to use
• CGI::Carp sometimes fails by Bod (2024) - it appears Bod is still using multidimensional array emulation
• Storable for user preferences by Bod (2023)
• Re: Storable for user preferences by afoken (2023)

See Also

• List Utils References
• Database References

Build and Test Automation References:

• Perl CPAN test metadata by me (2010)
• Data-driven Programming: fun with Perl, JSON, YAML, XML... by me (2015)

Updated: Many extra references added long after the original reply was made.

I knew the Raymond quote because it’s used as a chapter intro in some Perl book or another. I didn’t know the others. Good to see them.

Great quotes! "The Mythical Man Month" should be required reading.

James

There's never enough time to do it right, but always enough time to do it over...

Another advantage of a formal course is breadth of coverage. Learning only what you need to know at any given moment can provide a nice deep dive into that particular topic with the motivation that comes from being able to immediately apply it. For example, I know next to nothing about frameworks and CGI, because I've never had to learn it. I'd bet most Perl courses would cover them because that's a large part of what Perl is used for. Just not by me.