Let have a code:
use 5.014;
use warnings;
my $def = 'default_value';
# this works,.
# e.g. unless here are some arguments
# assigns to element0 the value $def
my(@arr) = (@ARGV);
push @arr, $def unless @arr;
say "args: @arr";
# this also works
# same for scalar - ARGV[0]
my $a1 = $ARGV[0] // $def;
say "arg1: $a1";
Exists some shorten way to assign default values to the array if here no @ARGV?
#this not works
#my(@arr) = (@ARGV) // ('def');
Assign value to array unless defined
There's no such thing as a defined or undefined array.
To assign to an array if it's empty,
@arr = 'def' if !@arr;
Exists some shorten way to assign default values to the array if here no
@ARGV?
@ARGV always exists.
To copy an array into another, using alternate values if the source array is empty, you can use the following:
my @arr = @ARGV ? @ARGV : 'def';
The simple
my @arr = @ARGV ? @ARGV : ('def');
where you may omit the parenthesis if there is indeed just one value to assign.
That last example doesn't work because //, ||, and && evaluate the definedness or truth of their left-hand side, so they impose a scalar context on their left-hand side (coerceing the array into a count of its elements). See it in perlop.
