C:\Windows\system32>perl -E "my @rray = qw(a b c); my $rx = qr(d); say
+ grep $rx, @rray"
abc
C:\Windows\system32>perl -E "my @rray = qw(a b c); say grep /d/, @rray
+"
[download]

I was trying to see if an array contained an element. I started by using the upper format and my code did not work. This was unexpected, because the perldoc for grep says:

grep EXPR,LIST

This is similar in spirit to, but not the same as, grep(1) and its relatives. In particular, it is not limited to using regular expressions. Evaluates the BLOCK or EXPR for each element of LIST (locally setting $_ to each element) and returns the list value consisting of those elements for which the expression evaluated to true. In scalar context, returns the number of times the expression was true.

To me, this meant that both forms should have worked. Why should I have read it as meaning that the first form should fail and the second work?

Regards,

John Davies

I offer a CUFP that I've concocted for one small task for one CPAN module. It's "cool" because helping perl with perl is kinda cool. Isn't it? Oh well, you'll decide.

The module I'm setting up for installation on a Gnu/Linux system (Debian lineage) is Imager. It's a good extension module and it uses external image libraries lke libpng and giflib. But unlike some newer modules, Imager doesn't use Alien::Some-Lib or anything to find and bind (see what I did there? I'm a poet! :-).

Here's what the Makefile.PL for Imager outputs for the user to see so that he can provision his system with those development libraries that aren't already present and findable:

Libraries *not* found:
  FT2
  GIF
  JPEG
  PNG
  TIFF
  Win32

Here's my fanciful way to process that output of perl Makefile.PL in the Imager source kit top dir:

The reader probably thinks it would have been far, far quicker to just use their distro's package manager (aptitude or whatever) than to write something like this. Of course, that's true, but personally I'd find it to be a lot less fun.

    – Soren
May 30, 2026 at 19:00 UTC