in reply to Accesing single element without args

If I understand correctly, you want to pass $r[0] back from sub interface_control to its caller? One way is to pass in a variable reference:

my $r;
my $s = ...;

interface_control($s, \$r);

# use $r here
...

sub interface_control
{
    my ($s, $r_ref) = @_;
    my (@r, $v, @h);
    $s->get_handles(rtrs=>\@r, vars=>\$v, hosts=>\@h);
    $$r_ref = $r[0];    # dereference $r_ref and write to its referent
    ...

[download]

See perlreftut. (Or, of course, you could just return $r[0] at the end of the subroutine.)

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

Replies are listed 'Best First'.
Re^2: Accessing single element without args
by Anonymous Monk on Mar 31, 2015 at 03:38 UTC

    The problem here is i can't modify interface_control. It is a global sub which is accessed by many users

    @r, has list of routers r[0]....rn, . I want to display output only for r[0] and not for other router

    If u see the below code ( under sub interface_control), i want to print blah only for r[0]. If i call interface_control($s), it may end up printing for all routers 

    
  foreach my $rh (@r) {
  print ("blah blah");

    [download]
[reply]
[d/l]

      Here is one (inelegant) approach which might work for you:

      #! perl
use strict;
use warnings;
use Capture::Tiny ':all';

my ($stdout, $stderr, @result) = capture
{
    interface_control();
};

my    @lines = split "\n", $stdout;
print $lines[0], "\n";

sub interface_control
{
    my @r;
    get_handles(\@r);
    print "blah blah for $_\n" for @r;
}

sub get_handles
{
    @{ $_[0] } = 11 .. 13;
}

      [download]

      Output:

      14:00 >perl 1204_SoPW.pl
blah blah for 11

14:00 >

      [download]

      Update: Removed unnecessary parentheses from print statement, plus a blank line.

      Hope that helps,

      Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

[reply]
[d/l]
[select]

        That makes sense :). I will try to use it if my code reviewer approves :)

        A final query on my question. As i want to print only r[0], is there a way to set the array @r to only r[0] during interface_control call

        . I mean like this 
        
push (@r, $r[0])

        [download]

        I know inside interface_control sub, i can set this, but interface_control can call from outside set this value ?

[reply]
[d/l]

      Well, then there is nothing you can do, short of doing something foolish like using PadWalker

[reply]

In Section Seekers of Perl Wisdom