Creating Fixed Length Records

[Greg Lindstrom]

Hello-

I'm creating fixed-length record layouts for various record translations 
I need to perform.  I have been using a home-grown object, 
"FixedLengthRecord" for about 4 years now and am very happy with it.  
Almost.  The burr under my saddle occurs when I serialize the record.  
Currently, I create an empty text field and for each record in my 
database (all record layouts, data types, lengths, defaults, etc. are 
held in an SQL server) I concatenate the field to the text segment.  I 
have been led to believe this is bad form because Python will copy the 
entire segment each time I add a field.  Up until now, it was not a big 
deal because the segments had at most 20 fields.  I have just been 
handed a record layout that is almost 5000 bytes long with 350 fields in 
it.  Gulp!!  Although I could let my object churn away on this bad boy, 
I'd like to know if there is a more pythonic way to serialize the record.

One thought I had, which might lead to an addition to the language, was 
to use the struct module.  If I could feed the pack method a format 
string then a tuple of values (instead of individual values), then I 
could create the format string once, then pass it a tuple with the 
values for that record.  Just a thought. 

So, gurus, what are your suggestions to tame this record?  Are there 
easier ways that I'm just not seeing?

Thanks,
--greg