20 best Perl questions at stackoverflow in 2017

This is the ten most rated questions at 2017 Stack Overflow.
Between brackets: question score & answers count
Built date: 2018/01/01 08:03:41 GMT

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1. What is _ (single underscore) in Perl without $ or @? - [38/2]
2. Creating a new regex based on the returned results and rules of a previous regex | Indexing a regex and seeing how the regex has matched a substring - [18/4]
3. Fastest way to find lines of a text file from another larger text file in Bash - [19/16]
4. Global regex match in while() on backtick result - [16/1]
5. How can I smoke out undefined subroutines? - [15/2]
6. How do I make a PSGI program do costly initialisation only once per process, not per thread? - [15/1]
7. Why doesn't Perl's foreach require its variable to be declared with my? - [12/1]
8. How to compile perl with DEBUG_LEAKING_SCALARS? - [12/1]
9. Executing Perl 6 code in Rmarkdown - [11/3]
10. Unexpected autovivification of arguments - [11/1]
11. How do I fake the client IP address in a unit test for a Mojolicious app? - [11/1]
12. Virtual Filesystem in Perl with Fuse - [10/1]
13. In-place Perl upgrade from source - [10/2]
14. Perl Dereferencing Syntax - [10/1]
15. Perl increment operator - [9/4]
16. Why isn't my overload::constant sub triggered when I use a string variable? - [10/2]
17. Perl CORE::say vs -E - [9/2]
18. Can I use a module, and later unload it shrinking the optree? - [9/2]
19. redefining or overloading backticks - [9/1]
20. Perl program leaking memory when compiling regex - [9/1]