Re: You can hack anything...

I am definitively with you on the point of using so many globals. I would never consider to do something like this on many global variables just because of efficiency concerns. A design that needs such hacks is probably flawed.

OTOH, I found this to be an interesting problem with respect to tie() usage.

As for your suggestion - thanks! This really works. Funny. You can even use the code like it stands. Just pass in a ref to the lexical, and you're done. Like this:

my $baz3;
tie($baz3, "MyGlobals", "LegacyRoutines::baz", \$baz3); 

print $baz3, "\n";
print $baz3, "\n";
[download]

Christian Lemburg
Brainbench MVP for Perl
http://www.brainbench.com

Comment on Re: You can hack anything... Download Code

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Re (tilly) 2: You can hack anything... by tilly (Archbishop) on Aug 08, 2001 at 20:40 UTC
But note that you are now responsible for manually syncronizing the variable you tie with the variable that gets untied. I would hide that with something like (untested): `sub lazy_init { tie $_[0], "MyGlobals", $_[1], \($_[0]); } # Then elsewhere lazy_init(my $baz3, "LegacyRoutines::baz"); print $baz3, "\n"; print $baz3, "\n";` [download] If you are going to propagate bad, unmaintainable hacks, there is still no excuse to not try to identify and kill potential causes of error. With enough hacks you can even make it look halfway decent... Of course it isn't really halfway decent. For instance if you avoid using the variable, you will have a memory leak. One solution is to manually untie somewhere. Of course that is something that can easily go wrong. With 5.6.x you can download and install WeakRef and use that to break the self-reference. For older versions of Perl you would need to untie. The cleanest safe way to do that is to return a ReleaseAction handle that will untie when it goes out of scope. Or you can play with the reference counts directly at the C level. With all of that, I think you get a reliable implementation of this feature. I still don't like it though.	[reply] [d/l]

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Re (tilly) 2: You can hack anything...
by tilly (Archbishop) on Aug 08, 2001 at 20:40 UTC

sub lazy_init {
  tie $_[0], "MyGlobals", $_[1], \($_[0]);
}

# Then elsewhere
lazy_init(my $baz3, "LegacyRoutines::baz");
print $baz3, "\n";
print $baz3, "\n";
[download]

Of course it isn't really halfway decent. For instance if you avoid using the variable, you will have a memory leak. One solution is to manually untie somewhere. Of course that is something that can easily go wrong. With 5.6.x you can download and install WeakRef and use that to break the self-reference. For older versions of Perl you would need to untie. The cleanest safe way to do that is to return a ReleaseAction handle that will untie when it goes out of scope. Or you can play with the reference counts directly at the C level.

With all of that, I think you get a reliable implementation of this feature. I still don't like it though.

[reply]
[d/l]