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Re: A new perl {cough} feature?

by chipmunk (Parson)
on Feb 18, 2002 at 05:17 UTC ( #146103=note: print w/replies, xml ) Need Help??


in reply to A new perl {cough} feature?

The answers are:

1) Perl has a special value for undef, called SV_UNDEF. Rather than create a separate 'undef' for each uninitialized value, Perl stores a pointer to this special undef value. Thus, the output from Data::Dumper is, in a way, correct; all of the uninitialized array elements are pointing to the same value, SV_UNDEF.

2) Auto-vivification. grep { 1 } @$_ for @matrix; treats each element of @matrix as an array reference, so the uninitialized elements are autovivified.

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Re: Re: A new perl {cough} feature?
by Anarion (Hermit) on Feb 18, 2002 at 17:30 UTC
    2.5) and why for can iterate over it and map chokes?

    Take a look at my code above

    $anarion=\$anarion;

    s==q^QBY_^=,$_^=$[x7,print

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