How do I get a slice from an array reference?

Question

Let us say that we have following array:

my @arr=('Jan','Feb','Mar','Apr'); my @arr2=@arr[0..2]; 

How can we do the same thing if we have array reference like below:

my $arr_ref=['Jan','Feb','Mar','Apr']; my $arr_ref2; # How can we do something similar to @arr[0..2]; using $arr_ref ? 

Answer 1

To get a slice starting with an array reference, replace the array name with a block containing the array reference. I've used whitespace to spread out the parts, but it's still the same thing:

 my @slice =   @   array   [1,3,2];  my @slice =   @ { $aref } [1,3,2]; 

If the reference inside the block is a simple scalar (so, not an array or hash element or a lot of code), you can leave off the braces:

 my @slice =   @$aref[1,3,2]; 

Then, if you want a reference from that, you can use the anonymous array constructor:

 my $slice_ref = [ @$aref[1,3,2] ]; 

With the new post-dereference feature (experimental) in v5.20,

use v5.20; use feature qw(postderef); no warnings qw(experimental::postderef);  my @slice = $aref->@[1,3,2]; 

Answer 2

Just slice the reference (the syntax is similar to dereferencing it, see the comments), and then turn the resulting list back into a ref:

my $arr_ref2=[@$arr_ref[0..2]];