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POHow can I iterate over an array with foreach without changing the address of the loop variable?
 

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  1. POHow can I iterate over an array with foreach without changing the address of the loop variable?
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    <p>When I run a simple bit of code like this:</p> <pre><code>my @arr=(1..5); my $x; foreach $x (@arr) { $x+=10; } print "@arr"; </code></pre> <p>The result is "11 12 13 14 15" because $x "becomes" each element in the @arr array in the foreach. Well enough.</p> <p>But here's my thing... not so much a problem (the solution is easy, but inelegant, and I want my perl to be as elegant as possible).</p> <p>I wrote a tie module for dealing with COBOL data. It takes a copybook, parses the fields, and then attaches that to a scalar/string so that access to/from the tied hash will return/set values in the string. It works wonderfully.</p> <pre><code>my %h,$rec; my $cb=&lt;&lt;END; 01 CH-RECORD. 05 JOB-NUM PIC X. 05 FILLER PIC X(76). 05 REC-TYPE PIC X(2). END tie %h, 'COBOLDataTie',$cb,\$rec; #tie the hash to the record via the copybook </code></pre> <p>From there, I can move a COBOL record to $rec and access the COBOL fields with the %h hash.</p> <p>Again, this works perfectly. But the problem comes when I want to iterate over, say, an array of COBOL records. So if after the above code I had something akin to:</p> <pre><code>foreach $rec (@arr) { print "Job is ",$h{'JOB-NUM'},"\n"; } </code></pre> <p>it won't work because the foreach actually changes the location of $rec, which breaks the tie on it. I end up having to do something like this:</p> <pre><code>foreach (@arr) { $rec=$_; print "Job is ",$h{'JOB-NUM'},"\n"; } </code></pre> <p>Is there any way I can do the "foreach $rec (@arr)" and not break my tied hash?</p> <p>(And before anyone says, yes I know this begs for a nice object-oriented solution... some day I'll get to that; I just have to find some time first)</p> <p>EPILOGUE: I revised the TieHash code to, instead of pointing to an external record, it intercepts "special" keys for the hash, among which is 'record'. So when I assign a record string to $h{'record'} it's the same as loading $rec in the example above. This is a far better solution, more self-contained. It also exposes a more OOP-like interface.</p>
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    1. CO@ikegame I think I see what OP means. Look at the second code block. He's tying `$rec` to the hash ... somehow.
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    2. COWhy are you using a [`tie`](http://perldoc.perl.org/functions/tie.html) based module? How is it better than just using an object?
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    3. COAs I indicated, I hadn't done an OOP version yet... maybe someday if my workload ever lightens. @simbabque, I'm actually tying to \$rec, not $rec.
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