Re: Flip-flop won't DWIM

This doesn't work, because of the (documented in perlop) magic comparison with $. when the conditions are constants:

Fix:

perl -lwe'$true=1; print for grep $true../D/, qw(A B C D E F)'
[download]

Note that it will flip for "E" (like your last version). What you probably intended is:

perl -lwe'my @a=qw(A B C D E F); print for grep ($_==1) .. ($a[$_]=~/D
+/), 0..$#a'
[download]

Or without a flip-flop:

perl -lwe'for (qw( A B C D E F )) { print; last if /D/ }'
[download]

Comment on Re: Flip-flop won't DWIM Select or Download Code

Replies are listed 'Best First'.
Re^2: Flip-flop won't DWIM by wu-lee (Beadle) on May 22, 2009 at 11:05 UTC
Thanks - in the end I also decided a flip-flop wasn't really necessary and used a more pedestrian loop. This post was mainly to see if there was in fact a nice way of using a flip flop in this case; I think ??../ D/ fits the bill.	[reply]
Re^3: Flip-flop won't DWIM by ikegami (Patriarch) on May 22, 2009 at 15:11 UTC
Not really `>perl -le"for (1..2) { print for grep scalar(??../D/), ('A'..'F'); }" A B C D` [download]	[reply] [d/l]
Re^4: Flip-flop won't DWIM by Roy Johnson (Monsignor) on May 26, 2009 at 16:22 UTC
An opportunity for the seldom-used reset function to come into play: `perl -le"for (1..2) { print for grep scalar(??../D/), ('A'..'F'); rese +t}"` [download] Caution: Contents may have been coded under pressure.	[reply] [d/l]