The use utf8 means Perl expects your source code to be UTF-8. The open pragma can change the encoding of the standard filehandles: use open qw( :std :encoding(UTF-8) ); And, whatever is going to deal with your output needs to expect UTF-8 too. If you want to see it correctly in your terminal, then you … Read more
perlvar is your friend. It documents all these cryptic special variables. $OUTPUT_AUTOFLUSH (aka $|): If set to nonzero, forces a flush right away and after every write or print on the currently selected output channel. Default is 0 (regardless of whether the channel is really buffered by the system or not; $| tells you only … Read more
The shebang must be the first line because it is interpreted by the kernel, which looks at the two bytes at the start of an executable file. If these are #! the rest of the line is interpreted as the executable to run and with the script file available to that program. (Details vary slightly, … Read more
It depends on what you want to have happen with STDERR and STDOUT. I prefer to send error and warning type messages to STDERR so that when someone is trying to redirect output to a file they still see the error messages; However, there are times though when STDOUT is used to communicate status to … Read more
Perl has a MASSIVE set of great testing tools that come with it! The Perl core has several tens of thousands of automated checks for it, and for the most part they all use use these standard Perl frameworks. They’re all tied together using TAP – the Test Anything Protocol. The standard way of creating … Read more
Check out Module::ScanDeps and the “scandeps.pl” utility that comes with it. It can do a static (and recursive) analysis of your code for dependencies as well as the %INC dump either after compiling or running the program. Please note that the static source scanning always errs on the side of including too many dependencies. (It … Read more
In Perl, a carriage return will serve in any place where a regular space does. Backslashes are not used like in some languages; just add a CR. You can break strings up over multiple lines with concatenation or list operations: print “this is “, “one line when printed, “, “because print takes multiple “, “arguments … Read more
Do you have a dependency loop? If Perl starts compiling your script and encounters a line like this: use PackageA; Perl pauses the compilation of your script; locates PackageA.pm and starts compiling it. If it encounters a line like this: use PackageB; Perl pauses the compilation of PackageA; locates PackageB.pm and starts compiling it. Normally, … Read more
Set $Data::Dumper::Sortkeys = 1 to get Perl’s default sort order. If you want to customize the order, set $Data::Dumper::Sortkeys to a reference to a subroutine that receives a reference to a hash as input, and outputs a reference to the list of the hash’s keys in the order you want them to appear. # sort … Read more
(sub { … }) will give you the pointer to the function so you must call by reference. (sub { print “Hello world\n” })->(); The other easy method, as pointed out by Blagovest Buyukliev would be to dereference the function pointer and call that using the { } operators &{ sub { print “Hello World” … Read more