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[REBOL] Little data trick

From: jeff::rebol::com at: 18-May-2001 11:09

Here's a little trick. Say you've got a little database you're making and sometimes you want to use only one field and sometimes you want to use two fields. For example you want to have a block of email and urls, but sometimes you only want to do searches over the emails and sometimes you want to get the urls from the emails as a key. Someone might do this: email-url-db: [ [a--example--com] [b--example--net] [c--example--org] [d--example--edu] ] just-emails: copy [] foreach [em url] email-url-db [append just-emails em] just-emails: make hash! just-emails email-url-db: make hash! email-url-db That's okay, but you can be sneaky if you save your database on disk so that it looks like this: ;===== %example-db.dat ================= [a--example--com] ; [b--example--net] ; [c--example--org] ; [d--example--edu] ; ;========================================= Now you can just do: dbf: %example-db.dat just-emails: load dbf email-url-db: load replace/all read dbf ";" # So when your script gets a new email and url you just add to the database: write/append dbf reform [new-email ";" new-url newline] You can of course extend the principal to as many fields as you like, put you just have to strip as many needed semicolons from each line before loading (read/lines). Important Caveat: You have to be sure that semicolon won't show up legitimately in any of your fields (safe with emails and urls). So while saving you would check to make sure the data doesn't contain the separator and change it appropriately. Anyhow, I just thought the trick was cute and figured I'd share. YMMV. -jeff