lhoward has asked for the wisdom of the Perl Monks concerning the following question:

In a tie constructor (TIESCALAR, TIEARRAY, TIEHASH, or TIEHANDLE) how can I access the value of the thing being tied? I really want to know how to do this for a TIEHANDLE, but I assume that the procedure would be about the same for any tie constructor. Similarly, can I set the tied variable during an untie?

Example code : I want to access the value of $t (or whatever the variable being tied is) in the TIESCALAR call. How can I get it? Or can I get it at all? 

package TestTie;
sub TIESCALAR{
  my $pkg=shift;
  my $obj=[] ;
  bless $obj, $pkg;
  return $obj;
}
package main;
my $t=9;
tie $t , 'TestTie';

[download]
I've been through the perltie docs, the Tie chapter of Advanced Perl Programming and the source code for several of the Tie:: modules, but can't seem to find any pointers.

Replies are listed 'Best First'.
RE: Access to tied variable in the tie constructor???
by Anonymous Monk on May 27, 2000 at 14:50 UTC
    You can pass additional arguments to tie, like this: 
    package TestTie;
sub TIESCALAR{
    my ($pkg, $object) = @_;
    my $obj=[] ;
    bless $obj, $package;
    print "$$object\n";
    return $obj;
}
package main;
my $t=9;
tie $t, 'TestTie', \$t;
    hth, g
[reply]
      I know that I can pass additional arguments to the tie, but I don't think I should have to. In my example $t is already an argument to the tie call and I don't want to have to pass it again. IMHO it looks redundant and un-clean to require the user of the tie to pass the tie variable twice and have the code look like: 
      tie $t, 'TestTie', \$t;

      [download]
[reply]
[d/l]

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