Globs and globals

[Eyck]

I've been bitten by a side effect, here's example code from documentation of Net::SSLeay::Handle:

   my $socket \*S1;
   if ($scheme eq "https") {
        tie(*S2, "Net::SSLeay::Handle", $socket);
        $socket = \*S2;
   }

This works OK, unfortunatelly I used it in a library inside object, so when you brought two life multiple such objects

for $sth (@sth) {
  my $object=new STH;
  $objects{$sth}=$object;
};

the whole shebang failed miserably (the last invocation of $object hides every other SSLeay::Handle (there is only one \*S2)

Now I'm trying to fix the code, here's my attempt which seems to work at the moment:

 {my $io=new IO::Handle; tie(*$io, "Net::SSLeay::Handle", $socket);$so
+cket = \*$io;};


 {
  my $io=new IO::Handle; 
  tie(*$io, "Net::SSLeay::Handle", $socket);
  $socket = \*$io;
 };

AFAIK this works because every $io=new IO::Handle generates unique identifier, so my code above might be replaced with

 $global-net-ssleay-counter++;
 tie(*$global.....

and it would still work, and wouldn't depend on chance (I hope two IO::Handle->new()don't get the same identifier).

What is the proper solution to this? How should I use Net::SSLeay::Handle?

[BrentDax]

The easiest way might be to just localize S1 and S2 first:

local(*S1, *S2);
...as in your first example...

OTOH, I don't think my $socket \*S1 is valid Perl--maybe there's an equal sign missing between $socket and \*S1?

[Eyck]

This advice is factually incorrect.

GLOB is a glob, and local doesen't help here ( besides providing false sense of security )

my $socket=\*S1;
print "Orig:",$socket,"\n";
{
local(*S1, *S2);
my $s=\*S1;
print "Local: ",$s,"\n";
}

Orig:GLOB(0x8160be4)
Local: GLOB(0x8160be4)

[BrentDax]

Odd--you're right, though I can't figure out why. The docs seem to say that you get a new glob when you localize:

The construct local *name; creates a whole new symbol table entry for the glob "name" in the current package. That means that all variables in its glob slot ($name, @name, %name, &name, and the "name" filehandle) are dynamically reset.

In any case, the following does work correctly:

open(S1, "/dev/null");
$a=*S1{IO};
{
    local(*S1);
    open(S1, "/dev/null");
    $b=*S1{IO};
}
print "$a $b\n";

IO::Handle=IO(0x101536f8) IO::Handle=IO(0x1013cdec)

[nobull]

What is the proper solution to this?

The proper solution would be for Net::SSLeay::Handle to provide a new() method.

Absent that you solution using IO::Handle is probably the best except I'd probably simplfy $socket=\*$io to $socket=$io.

[dragonchild]

You could also use gensym (part of Symbol), the way IO::Handle does. (Read the code ... it's actually quite simple.)