variable interpolation within a range operator

kri54sub has asked for the wisdom of the Perl Monks concerning the following question:

newbie question:

How do I use variable interpolation within a range operator?

eg: <THIS WORKS>

   while (<FH>) {
       print  if (
         (/Btree/../PSE:/) or (m#PROCESSING ../Btree.gz#)
         or
         (m#PROCESSING ../log.dummy-10-05-18-05.gz#)
         or
         (m#PROCESSING ../log.dummy-10-01-06-05.gz#)
       )
    }

----------------------------------------------------
[download]

Instead of the above relative hard coded path, I want to use a variable which can be interpolated within this range operator, as in

@ARGV = qw#../log.dummy-10-01-06-05.gz ../log.dummy-10-05-18-05.gz ../
+Btree.gz/#;

foreach $input (@ARGV) {
    open (FH,"zcat $filename|") or die "Can't Open file: $!\n";
        while (<FH>) {
           print if (
              (/Btree/../PSE:/) or (m#PROCESSING ../$input#)
           )
        }
}
[download]

But this doesn't work. Any suggestion on this interpolation. I tried the `$input` as well.

Comment on variable interpolation within a range operator Select or Download Code

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Re: variable interpolation within a range operator by kyle (Abbot) on Feb 26, 2008 at 03:25 UTC
You're interpolating `$input` with a value such as `'../log.dummy-10-01-06-05.gz'` into the pattern `m#PROCESSING ../$input#`. After the interpolation, that's `m#PROCESSING ../../log.dummy-10-01-06-05.gz#`. That's different from the working pattern you had before (`m#PROCESSING ../log.dummy-10-01-06-05.gz#`). One thing you'll want to do, since you're matching literal strings, is to use quotemeta or `\Q` in the pattern. As it is, when you interpolate `$input`, the initial dots in `'../log.dummy-10-01-06-05.gz'` could match any character (as they normally would in a regexp). In short, I think you want this: `m#PROCESSING \Q$input#` [download] If I may make a few more suggestions... Please don't use `#` as delimiters. It really plays havoc with my context-sensitive editor. I personally like `m{}`. Since you're looking for literal strings, index would be faster (but maybe harder to read). Use three argument open: `open my $zcat_fh, '-\|', "zcat $filename" or die ...` Have a look at Writeup Formatting Tips. Specifically, you need `<code>` tags around your code to make it look right. If you don't already, use strict and warnings.	[reply] [d/l] [select]
Re^2: variable interpolation within a range operator by kri54sub (Initiate) on Feb 28, 2008 at 00:19 UTC
Thank you for quotemeta and the suggestions especially the 3 argument open command. I do use strict and warning. For posting purposes I just took only a snippet of my code. Thanks again for the help.	[reply]
Re: variable interpolation within a range operator by jwkrahn (Abbot) on Feb 26, 2008 at 04:40 UTC
You could do it like this: `@ARGV = map "zcat $_ \|", qw[ ../log.dummy-10-01-06-05.gz ../log.dummy-10-05-18-05.gz ../Btree.gz/ ]; while ( <> ) { print if /Btree/ .. /PSE:/ or /PROCESSING \Q$ARGV/; }` [download]	[reply] [d/l]