You can use a character class: /[^\s\\]/ matches anything that is not a whitespace character nor a \. Here’s another example: [abc] means “match a, b or c“; [^abc] means “match any character except a, b or c“.
In general, bless associates an object with a class. package MyClass; my $object = { }; bless $object, “MyClass”; Now when you invoke a method on $object, Perl know which package to search for the method. If the second argument is omitted, as in your example, the current package/class is used. For the sake of … Read more
PHP 5.3 has a shorthand ?: operator: $foo = $bar ?: $baz; Which assigns $bar if it’s not an empty value (I don’t know how this would be different in PHP from Perl), otherwise $baz, and is the same as this in Perl and older versions of PHP: $foo = $bar ? $bar : $baz; … Read more
In perl, they result in the same opcodes: $ perl -MO=Concise -e ‘for(;;) { print “foo\n” }’ a <@> leave[1 ref] vKP/REFC ->(end) 1 <0> enter ->2 2 <;> nextstate(main 2 -e:1) v ->3 9 <2> leaveloop vK/2 ->a 3 <{> enterloop(next->8 last->9 redo->4) v ->4 – <@> lineseq vK ->9 4 <;> nextstate(main 1 … Read more
You can do something like this as demonstrated in perlfaq4: sub uniq { my %seen; grep !$seen{$_}++, @_; } my @array = qw(one two three two three); my @filtered = uniq(@array); print “@filtered\n”; Outputs: one two three If you want to use a module, try the uniq function from List::MoreUtils
There are a few ways: $0 is the currently executing script as provided by POSIX, relative to the current working directory if the script is at or below the CWD Additionally, cwd(), getcwd() and abs_path() are provided by the Cwd module and tell you where the script is being run from The module FindBin provides … Read more
UPDATE: This question was the subject of my blog on the 15th of October, 2012. Thanks for the great question! What does it really mean for a language to be “weakly typed”? It means “this language uses a type system that I find distasteful”. A “strongly typed” language by contrast is a language with a … Read more
perl -pe ‘chomp if eof’ filename >filename2 or, to edit the file in place: perl -pi -e ‘chomp if eof’ filename [Editor’s note: -pi -e was originally -pie, but, as noted by several commenters and explained by @hvd, the latter doesn’t work.] This was described as a ‘perl blasphemy’ on the awk website I saw. … Read more
Data::Dumper is your friend. use Data::Dumper; my %hash = (‘abc’ => 123, ‘def’ => [4,5,6]); print Dumper(\%hash); will output $VAR1 = { ‘def’ => [ 4, 5, 6 ], ‘abc’ => 123 };
Thanks to Peter van der Heijden, here’s one that’ll work for filenames with spaces in them: for f in * ; do mv — “$f” “PRE_$f” ; done (“–” is needed to succeed with files that begin with dashes, whose names would otherwise be interpreted as switches for the mv command)