The caller() function and $wantarray

The argument of interest is the $wantarray argument. This indicates what return value is

expected of the subroutine from where it was called. The subroutine could have been

called in void context meaning the return value is thrown away. Or it could have been

called and the return value assigned to a scalar. Or it could have been called and the

return value assigned to a list of scalars.

sub CheckMyWantArray

{

my @info = caller(0);

my $wantarray = $info[5];

$wantarray='undef'

unless(defined($wantarray));

print "wantarray is '$wantarray'\n";

}

CheckMyWantArray; # undef

my $scal = CheckMyWantArray; # 0

my @arr = CheckMyWantArray; # 1

> wantarray is 'undef'

> wantarray is '0'

> wantarray is '1'