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If one is designing from scratch, then you are right, fixed-width is not extensible nor self-documenting. But I know that Valley Media, the company who does fulfillment for Amazon.com and CDNOW and some other people I have worked for, does use fixed-width format and they have too much technology behind it too change in midstream. I would be surprised if they are the only such place using this admittedly inferior format.

Regarding use pack and unpack instead of Parse::FixedLength, Text::FixedLength, and Text::FixedLength::Extra, if you read "Data Munging with Perl", the answer would be none, because he did not mention the FixedLength module set in his book, but instead focused on pack and unpack.

I think pack and unpack are excellent for implementation of fixed-width data processing, but in terms of making a human-level description, a higher level interface is needed. For example, let's say I have this:
field name field width justifiction numeric?
catalog id 12 L no
price 6 L yes -- with 2 decimal places

Here is a high-level description that one could expect a data-entry expert to convert the english above into:

catalog_id = '12L', price = '6L*2'
and to turn that into the programmatic representaiton of Parse::FixedLength is a one-step transformation:
package Business::Logic::Orders; our $line_data = [ { catalog_id => '12L' } , { price => '6L*2' } ]; 1;
And then the script which plugs into the data description is quite clean, with no low-level Perl pack/unpack:
### open D, 'data-file.dat'; while (<D>) { Parse::FixedLength::Parse(\%line_parse, $Business::Logic::Orders); DBIx::Recordset->Insert({ \%dsn }, \%line_parse} ); }
And of course, internally Parse::FixedLength can implement it's high-level API with pack, unpack, or sprintf as need be.

In reply to Re: Re (tilly) 2: Text::xSV by princepawn
in thread Text::xSV by tilly

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