in reply to How to access outside variable

You can't.

To access both variables the inner and outside variables must be in different packages. In fact, all you are doing in the code above is overwriting the old value (10) with a new value (11).

To be able to access two variables with the same name at the same time, you would have to do something like this:

package Frick;

# this variable will have the full name $Frick::a;
#our makes the variable sharable between packages
our $a=10;
{
  package Frack;

  # This variable will have the full name $Frack::b;
  # my limits $Frack::b to the package Frack.
  # No other package will be able to see or use its value
  my $a=11;

   print "Frick says $Frick::a, Frack says $a, $Frack::a\n";
  #prints: frick says: 10, frack says: 11, 11;
}

[download]

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Re^2: How to access outside variable
by Anonymous Monk on Jan 21, 2011 at 05:41 UTC
    Sorry,

    The variable declared as my.

    Rewriting the code

    my $a=10;
{
   my $a=11;
   print $a;
}

    [download]

    Please consider the file is not an module. It is just simple .pl file.

    I want print value of $a is 10 inside the block which is declared on outside.

[reply]
[d/l]

      You still can't access the outer value without putting the variables in separate packages and declaring the outer one with our. The second inner my declaration "hides" the first outer my declaration. If you want to access two variables with the same name, you have to give them separate packages, even if it all happens in a single .pl file.

      Packages aren't necessarily modules. You can have many package declarations in a single file and many files sharing the same package declaration. Packages are just namespaces you can use to group together variables and scope them logically rather than via text position (inside/outside curly braces).

      If you really, really don't want to use packages to scope your variables, then you will have to give your inner and outer variables different names. Is there a particular reason you aren't doing that already?

[reply]

        Thanks for giving good explanation.

        This question asked in my interview panel.

[reply]

      In case the inner scope isn't just a plain block, but a subroutine, you can use PadWalker to get at the outer scope(s): 

      use PadWalker qw(peek_my);

my $a=10;
sub {
    my $a=11;
    my $my = peek_my(1);    # one level up

    print ${$my->{'$a'}};   # 10
    print $a;               # 11
}->();

      [download]

      This isn't meant for everyday consumption, though... — better use unambiguous variable names.

[reply]
[d/l]
      Do it before you override it
[reply]

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