11–20 of 32 posts
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…
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. 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.
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.
> !! Bang bang boolean conversion 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. T…
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.
> !! Bang bang boolean conversion 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. T…
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!
> !! Bang bang boolean conversion 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. T…
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 bra…
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. But sometimes one can still want to write poetry.
I don't believe you.
> !! Bang bang boolean conversion 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. T…
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…
But looks like Perl's implementation is more limited compared to other languages:
% perl -e 'print ~-(0), "\n"'
18446744073709551615
% ruby -e 'print ~-(0), "\n"'
-1