Re: [PLUG] question re: perl diamond operator

["Mark M. Hoffman" <mhoffman@lightlink.com>]

Hi:

* Paul W. Roach III <paul@isaroach.com> [2009-06-25 14:23:22 -0400]:
>    Yeah...
>    *
>    #!/usr/bin/perl
>    *
>    foreach my $file (@ARGV) {
>    ** open(FILE, $file) || die "couldnt open file $file: $!\n";
>    ** chomp(my @lines = <FILE>);
>    ** close(FILE);
>    *
>    ** print @lines;
>    }

Yes obviously... but then I lose the ability to (also) do this:

	$ some_command | ./example.pl

I asked about the diamond operator, specifically, for good reason.

>    On Thu, Jun 25, 2009 at 1:14 PM, Morgan Jones <[1]morgan@morganjones.org>
>    wrote:
> 
>      You could also loop through %ARGV and test each value.
> 
>      [2]http://en.wikipedia.org/wiki/There%27s_more_than_one_way_to_do_it
>      -morgan
> 
>      On Jun 25, 2009, at 1:03 PM, Mark M. Hoffman wrote:
> 
>      > Hi:
>      >
>      > * Morgan Jones <[3]morgan@morganjones.org> [2009-06-25 12:47:38
>      -0400]:
>      >> #! /usr/bin/perl -w
>      >>
>      >> if (! -f $ARGV[0]) {
>      >> * * print "$ARGV[0] does not exist\n";
>      >> * * exit 1;
>      >> }
>      >>
>      >> while (<>) {
>      >> * * *chomp;
>      >> * * *print $_;
>      >> }
>      >
>      > Sure I could do that, but consider...
>      >
>      > * * * $ ./example.pl this_file_exists but_not_this_one
>      >
>      > It's a bit indirect, but I've solved it a completely different way.
>      > I added
>      > the following line near the top... it installs a warning handler
>      > which just
>      > converts all warnings into fatal errors. *Good enough for me.
>      >
>      > * * * local $SIG{__WARN__} = sub { die $_[0] };
>      >
>      >> On Jun 25, 2009, at 12:24 PM, Mark M. Hoffman wrote:
>      >>
>      >>> Hi all:
>      >>>
>      >>> Given the following trivial script:
>      >>>
>      >>>>> #! /usr/bin/perl -w
>      >>>>>
>      >>>>> while (<>) {
>      >>>>> * chomp;
>      >>>>> * print $_;
>      >>>>> }
>      >>>
>      >>> * * $ ./example.pl foo
>      >>> * * Can't open foo: No such file or directory at ./example.pl line
>      3.
>      >>>
>      >>> So far so good; the file foo really does not exist.
>      >>>
>      >>> * * $ echo $?
>      >>> * * 0
>      >>>
>      >>> Really? *I want the exit status to be non-zero here. *I've looked
>      >>> through the
>      >>> perl documentation; I can't see any way to get the diamond operator
>      >>> to do what
>      >>> I want in this case. *I would appreciate any suggestions from perl
>      >>> experts.
>      >

Regards,

-- 
Mark M. Hoffman
mhoffman@lightlink.com

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