Both of your alternatives (one-line-ish, and using a sub) are very hard to read, and require lots of duplicate code for each message type. Hide the gory details, leaving a clean interface (such as those below). This process is called encapsulation.

A procedural interface: 

my $TEST_REC_FORMAT = get_msg_format [
   status => 'n  ',   #   0
   time   => 'n  ',   #   2
   date   => 'N  ',   #   4
   code   => 'a16',   #   8   key
   msid   => 'a10',   #  24   key
];

my %test_vals = parse_msg($TEST_REC_FORMAT, $rec);

[download]

An OO interface: 

my $TEST_REC_FORMAT = MessageFormat->new([
   status => 'n  ',   #   0
   time   => 'n  ',   #   2
   date   => 'N  ',   #   4
   code   => 'a16',   #   8   key
   msid   => 'a10',   #  24   key
]);

my %test_vals = $TEST_REC_FORMAT->parse($rec);

[download]

What exactly get_msg_format or new returns is not important. How exactly it is calculate is not important either.

In reply to Re: Clarity in parsing fixed length data. by ikegami
in thread Clarity in parsing fixed length data. by rodion

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