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Re^3: The Null Mull (or, when OO needs more O)

by hardburn (Abbot)
on Nov 29, 2004 at 19:07 UTC ( #411008=note: print w/replies, xml ) Need Help??

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

"There is no shame in being self-taught, only in not trying to learn in the first place." -- Atrus, Myst: The Book of D'ni.

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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;

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

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