Subj : Re: dangers of operator overloading
To   : comp.programming
From : rem642b
Date : Sat Aug 20 2005 01:15 am

> From: "Rob Thorpe" <robert.tho...@antenova.com>
> Or, if no-ones going to look in the file, then you can make the file a
> lisp program.  To form the data structure the program is executed.
> That way if the representation of the data on file is changed the only
> thing that needs to change is the program that writes this program out.
> (This also assumes you don't care about security)

I don't like that solution at all, for precisely the reason you cite
(security). If someday you decide you need security, if you have just a
data file, it's easy to encrypt it and delete the original, and then
decrypt it on-the-fly only at safe times, and immediately delete the
decrypted version whenever there's a security breach. But if you have
an actual program that generates the confidential data, it's not so
easy to encrypt the source for storage and then decrypt it and compile
it and run it all on the fly and the delete the source and object and
data when there's a security breach.

If you need a different data format, you simply write a converter from
the native-lisp-sepxr format to whatever new data format you need. It's
a lot easier to invent an output routine for a new syntax than to
invent an input routine for a new syntax, so with the original data
always in s-expression format the hard part is already done and all you
have to do is the easy part each time you change the runtime format of
data. (You might even have more than one runtime format, such as a
forward and a backward lookup table, each generated from the same
s-expression input.)

.