Perl was the first language I learned on my own after graduating university many years ago. I fell in love with it because of quirks like these and because code written in it can have a poetic quality you don't see often.
Now I am old and joyless and I want the code I write for work to be boring and unsurprising.
I learned Perl after trying C; and after struggling with `scanf` (not even getting to tokenization), the ease and speed of `while (<>) { @A = split;` for text-handling made it easy to fall in love. This (in the mid 90s, before Java, JavaScript, and C++ TR1) was also my first contact with associative arrays.
I was also drawn to the style of the Camel Book.
More than most other languages, Perl encouraged one-liners. When I later read PG's "Succinctness is power" essay, I thought of Perl.
> This (in the mid 90s, before Java, JavaScript, and C++ TR1) was also my first contact with associative arrays.
Associative array is just a fancy term for map / dictionary. C++ has always had one of those, even before TR1: std::map (which is a tree under the hood). It does have the extra requirement that your key be ordered, which isn't part of the core definition of associate array[1]. But usually it's not a problem even if you don't actually need the ordering.
As I think you're implying, TR1 / C++11 added std::unordered_map, which is a hash table and doesn't need keys to be ordered (just hashable).
[1] It isn't part of the core definition of "map" either, which despite C++'s usage just means the same thing as dictionary / associative array. A lot of those early STL containers are confusingly named: e.g., in general, "list" just means some ordered sequence of elements, so it covers static arrays, dynamic arrays, and linked lists, but C++ uses this term for linked lists, probably the least likely understood meaning. It use of the term "vector" for contiguous dynamic arrays is very odd. But I'm now way off topic...
Perl was also my first productive language, and I do miss it a little. Write something like []string{"foo", "bar", "baz"} in go and you really appreciate qw(foo bar baz). Perl was always designed to be easy to type in, and maybe not so easy to maintain later. Good memories, but not for me anymore.
This isn't the first time I've said this but also had an early-career job writing Perl code. And I actually got to the point where I liked it -- I mean I could see why it had a following.
Subsequently I've written code in almost every popular programming language and I will frequently go years between languages but even so I have very little trouble picking them back up. Even C++. But not Perl. It's just so weird with so many idiosyncrasies that I just can't remember it.
I discovered Perl directly after PHP before Web 2.0 days. Compared with the extreme, Java or (contemporary) Go, Perl codes (can) have a soul. Interestingly, modern ECMAScript (JS) brought in a few of the nice breweties from Perl world which I haven't seen a long time.
When I started out as a sysadmin it was all shell and glue and different syntax on the 8 different flavours of *NIX I worked on between '94 and '97, then I found Perl suddenly you could actually build things that felt "real". It took me straight into web application development by '98, and I'm not sure I would have stayed in this field had it not existed (I was also working in neuro-diagnostics at the time and might have stayed there).
I saw some really elegant stuff written in Perl.
I also saw some absolutely unhinged, impossible-to-maintain garbage.
After first experiences with linux shell scripting, sed, awk, and C in 1990s, I found perl a welcome refuge. Way more featureful than DOS .bat files or BASIC! Its capabilities (perl + cpan) have always well exceeded my need for CS goodness. People do complain about the syntax, oddly, without mentioning the numerous ways perl was designed to make common tasks easy to do. The "use strict" pragma, and early adoption of testing culture are two examples where perl led the programming community. With the continued maturing of the language and ecosystem, I can only smile at the naysayers and wish them happiness whatever the language.
This isn't a special operator. This is just how "not" (!) works. In basically every language: C, C++, Javascript, Perl, etc., ! is the "not" operator so !12 gives you false (12 is truthy), and !!12 (not false) gives you true.
It's the same in languages that use different operators for "not". In python, the "not" operator is just the word not, and can write "not not 12" to get True. They didn't implement a special "not not" operator, anymore than Perl implemented a "!!" operator. They just implemented the basic ! / "not" operator.
Right, that's the point of TFA. It doesn't list "special" operators, it lists "secret" operators -- that is, operators combined from existing sigils that do clever things.
The "Venus" operator is a good example: it's the '+' addition operator! You just add zero to a value that's coercible into a number.
The Eskimo operators are also interesting: similar to a SQL injection attack, you use a close brace and an open brace to stop and start a new code block from within a string that's sent to the interpreter. Perl didn't invent open and close braces: hence the verb "discover" rather than "implement".
The whole page is a bit of a lark, and a good example of why some of us don't enjoy Perl!
Keep in mind that applying the logical NOT operator twice (using `!!`) converts any integer expression into a strict boolean.
Any non-zero value becomes `1`, and zero remains `0`. This is commonly used for boolean normalization
when the original expression yields a bitmask or arbitrary integer.
While the same result can be written as `(x != 0)`, the `!!x` idiom is concise, widely used in low-level
C code, guarantees a result of exactly `0` or `1`, and works well in macros and constant expressions.
That is true, but for the kind of code where I might use this trick, there usually aren't enough `~-$x` for `use integer;` to be worthwhile, I would just do `($x-1)` instead.
fun thing about this page: i have gemini in the browser and when I asked it 'why is the entire Wall Family naming these things?' it said it couldn't engage. Turns out 'goatse' is a forbidden word to Gemini.
Perk is... quite a thing. I think if you like programming because you like believing you have secret knowledge... go for it. Perk will scratch that itch. But I do not believe it beings you closer to the pantheon of God's. Ai n't gonna stop anyone from dancing with the Satyrs though, if that's your jam.
Now I am old and joyless and I want the code I write for work to be boring and unsurprising.
But sometimes one can still want to write poetry.
I learned Perl after trying C; and after struggling with `scanf` (not even getting to tokenization), the ease and speed of `while (<>) { @A = split;` for text-handling made it easy to fall in love. This (in the mid 90s, before Java, JavaScript, and C++ TR1) was also my first contact with associative arrays.
I was also drawn to the style of the Camel Book.
More than most other languages, Perl encouraged one-liners. When I later read PG's "Succinctness is power" essay, I thought of Perl.
https://paulgraham.com/power.html
Associative array is just a fancy term for map / dictionary. C++ has always had one of those, even before TR1: std::map (which is a tree under the hood). It does have the extra requirement that your key be ordered, which isn't part of the core definition of associate array[1]. But usually it's not a problem even if you don't actually need the ordering.
As I think you're implying, TR1 / C++11 added std::unordered_map, which is a hash table and doesn't need keys to be ordered (just hashable).
[1] It isn't part of the core definition of "map" either, which despite C++'s usage just means the same thing as dictionary / associative array. A lot of those early STL containers are confusingly named: e.g., in general, "list" just means some ordered sequence of elements, so it covers static arrays, dynamic arrays, and linked lists, but C++ uses this term for linked lists, probably the least likely understood meaning. It use of the term "vector" for contiguous dynamic arrays is very odd. But I'm now way off topic...
Subsequently I've written code in almost every popular programming language and I will frequently go years between languages but even so I have very little trouble picking them back up. Even C++. But not Perl. It's just so weird with so many idiosyncrasies that I just can't remember it.
Unfortunately I had a different experience with the Ruby community, so I eventually switched to Python along with apparently everybody else.
I don't believe you.
When I started out as a sysadmin it was all shell and glue and different syntax on the 8 different flavours of *NIX I worked on between '94 and '97, then I found Perl suddenly you could actually build things that felt "real". It took me straight into web application development by '98, and I'm not sure I would have stayed in this field had it not existed (I was also working in neuro-diagnostics at the time and might have stayed there).
I saw some really elegant stuff written in Perl.
I also saw some absolutely unhinged, impossible-to-maintain garbage.
This isn't a special operator. This is just how "not" (!) works. In basically every language: C, C++, Javascript, Perl, etc., ! is the "not" operator so !12 gives you false (12 is truthy), and !!12 (not false) gives you true.
It's the same in languages that use different operators for "not". In python, the "not" operator is just the word not, and can write "not not 12" to get True. They didn't implement a special "not not" operator, anymore than Perl implemented a "!!" operator. They just implemented the basic ! / "not" operator.
The "Venus" operator is a good example: it's the '+' addition operator! You just add zero to a value that's coercible into a number.
The Eskimo operators are also interesting: similar to a SQL injection attack, you use a close brace and an open brace to stop and start a new code block from within a string that's sent to the interpreter. Perl didn't invent open and close braces: hence the verb "discover" rather than "implement".
The whole page is a bit of a lark, and a good example of why some of us don't enjoy Perl!
Any non-zero value becomes `1`, and zero remains `0`. This is commonly used for boolean normalization when the original expression yields a bitmask or arbitrary integer.
While the same result can be written as `(x != 0)`, the `!!x` idiom is concise, widely used in low-level C code, guarantees a result of exactly `0` or `1`, and works well in macros and constant expressions.
Confusingly (to some) they are integers and while 0 represents FALSE, any non 0 value represents TRUE.
It's pedantic, apologies, but that is why the GP refers to "convert to strict boolean"
But looks like Perl's implementation is more limited compared to other languages:
https://metacpan.org/dist/perlsecret/view/lib/perlsecret.pod...if ($text =~ /error/) { print "Found error\n"; }
if ($text !~ /error/) { print "No error found\n"; }
It's just fun and fast to slice and dice text this way.