Hi Peter,
I played a bit with glob vs. combine_nk from "The Art of Computer
Programming" by Knuth, and received:
ernie:DBI-Test sno$ time perl -MData::Dumper -le 'my @l = (1 .. 20); my
@x = map { [ grep { $_ != 0 } split(//,$_) ] } glob( join( "", map {
"{0,$_}" } @l ) ); print scalar @x'
1048576
real 0m16.314s
user 0m12.443s
sys 0m3.861s
ernie:DBI-Test sno$ time perl -Mlib=lib -MData::Dumper -MDBI::Test::Conf
-e 'my @l = (1 .. 20); my @x = map {
DBI::Test::Conf::combine_nk(scalar(@l), $_); } (1 .. scalar @l); print
scalar @x'
1048575
real 0m5.229s
user 0m4.997s
sys 0m0.226s
So iterating and mapping test variants from got combinations list
should be much faster using the Knuth algorithm. It doesn't matter
for less amount of possible combinations, but for larger amounts ...
Cheers
--
Jens Rehsack
