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This is a japh using duff's device. If you want to understand it, make sure you know what duff's device is (google it or see http://www.faqs.org/docs/jargon/D/Duff's-device.html).

This may fail if perl is compiled with long doubles or some 64bitness.

I run it successfully with perl5.{00503(if deleted "no warnings"),6.1,8.0,8.1} on i686-linux and perl5.6.1 on sun4-solaris (sparc).

# the usual declarations you use in evry program no warnings; no strict; # initialize arrays @a= ( 2.9230032746618539e+48, 3.7537584144024476e+255, 8.7398998774645058e+245, 5.7277807836951398e+250, 1.4916681462400519e-154, 1.7573882009934739e+159, 7.2294757342932134e+221, 4.7379092172264014e+226, 5.7277807836951398e+250, 9.1248812352446012e+192, 3.2418090381883485e+178, 1.3336028865760046e+241, 1.4916681462400519e-154, 2.315841784746365e+77, 3.2418090381883485e+178, 1.3336028865760046e+241, 1.6832434884955199e+212, 1.4916681462400519e-154, 9.1248812352446012e+192, 1.7573882009934739e+159, 7.5479248496432486e+168, 2.5684257331779778e+207, 3.2418090381883485e+178, 1.3336028865760046e+241, 1.6259745436952359e-260 ); tie @b, &^Px$^P; # with duff's device I can copy array very efficently goto ("case" . (@a % 8)); while ($a < @a) { case0: $b[$b++] = $a[$a++]; case7: $b[$b++] = $a[$a++]; case6: $b[$b++] = $a[$a++]; case5: $b[$b++] = $a[$a++]; case4: $b[$b++] = $a[$a++]; case3: $b[$b++] = $a[$a++]; case2: $b[$b++] = $a[$a++]; case1: $b[$b++] = $a[$a++]; }; # oh, I nearly forgot magical subs, so here they are sub DESTROY { } sub AUTOLOAD { ($#, %c)= qw(%c $#); print $_[2]; bless []; } __END__

I wonder if you can see how it works, especially what the two magic subs do. If you know, please reply me. (Is this too trivial?)


In reply to Fun with duff's device and AUTOLOAD by ambrus

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