in reply to Re^2: The Null Mull (or, when OO needs more O)
in thread The Null Mull (or, when OO needs more O)

I just ran your code on 5.8.4 i686-Linux with the same result you did. I'm not sure what is going on here--someone with more understanding of the internals is needed. My guess is that undef isn't staying shared like I expected it would.

It does work with taking a reference to undef, but this breaks the transparency I was hoping for:

BEGIN {
    &Internals::SvREADONLY(\undef, 0);
    undef = 42;
    &Internals::SvREADONLY(\undef, 1);
}

my $x = ${ \undef };
print( ((undef) ? 'True' : 'False'), $/);
print( ((defined undef) ? 'True' : 'False'), $/);
print( (($x) ? 'True' : 'False'), $/);
print( ((defined $x) ? 'True' : 'False'), $/);
print $x, $/;

__OUTPUT__
True
True
True
True
42

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Re^4: The Null Mull (or, when OO needs more O)
by dragonchild (Archbishop) on Nov 29, 2004 at 19:29 UTC 
    BEGIN {
    &Internals::SvREADONLY(\undef, 0);
    undef = 42;
    &Internals::SvREADONLY(\undef, 1);
}

use constant UNDEF => ${ \undef };

my $x = UNDEF;

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    Which is probably better because you're commenting that you did something funky with undef. *shrugs*

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    Being unknowing, is not the same as being stupid.
    Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence.
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