### Re: Flip-flop won't DWIM

by akho (Hermit)
 on May 21, 2009 at 15:49 UTC ( #765484=note: print w/replies, xml ) Need Help??

in reply to Flip-flop won't DWIM

The /./ matches E, so flip-flop starts over.

Replies are listed 'Best First'.
Re^2: Flip-flop won't DWIM
by Roy Johnson (Monsignor) on May 21, 2009 at 20:30 UTC
So use the match-once operator (no need for an actual pattern; the empty pattern works fine):
print join ' ', grep scalar(??../D/), ('A'..'F');

Caution: Contents may have been coded under pressure.
Aha! Finally, a use for the match-once operator! And it seems to be tailor made for this problem. Bravo!
Re^2: Flip-flop won't DWIM
by akho (Hermit) on May 21, 2009 at 15:57 UTC
Yes. However, List::MoreUtils is not in core, so it's not something I want to rely on in the current circumstance.
Re^2: Flip-flop won't DWIM
by wu-lee (Beadle) on May 21, 2009 at 15:58 UTC
Right. Of course, silly me.

Ok, so this does what I want:

perl -lwe '\$x = 1; print join " ", grep { scalar(\$x++../D/) } qw(A B C + D E F)' # prints: # A B C D
Although this is not particularly neat. Is there a better way?
Your code prints "A B C D E F" for me, and I cannot see why it would print anything else.

This seems to work if you insist on using flip-flop:

\$x = 1; print join " ", grep { \$x..((\$x=0) or /D/) } qw(A B C D E F);
However, you could copy stuff from List::MoreUtils.
Actually, that doesn't, but this does:
perl -lwe '\$x = 0; print join " ", grep { scalar(!\$x++../D/) } qw(A B + C D E F)' # prints: # A B C D
The "++" does nothing.

Create A New User
Node Status?
node history
Node Type: note [id://765484]
help
Chatterbox?
and the fog begins to lift...

How do I use this? | Other CB clients
Other Users?
Others imbibing at the Monastery: (3)
As of 2017-08-21 07:36 GMT
Sections?
Information?
Find Nodes?
Leftovers?
Voting Booth?
Who is your favorite scientist and why?

Results (318 votes). Check out past polls.

Notices?