Why I miss strong variable typing in scripting languages

I love strong typed languages.  Languages that require you to define all variables before use.  They save me from myself, or, from my attrocious spelling.  I was working on LibraryFind, OSU’s opensource metasearch service, three days ago making a few tweaks and changes.  One of the things that this tool has that is somewhat researchy — is this idea of caching all results and how that cache gets reutilized in different sessions.  Anyway, I was making a few changes to the following lines:

      #======================================================
      # Check to see if data was cached -- if it is load
      #======================================================
      if _search_id != nil
         _lxml = CachedSearch.retrieve_metadata(_search_id, _collect.id, _max.to_i)
         if _xml != nil
           if _lxml.status == LIBRARYFIND_CACHE_OK
             if _lxml.data != nil
               _lrecord =  _objRec.unpack_cache(_lxml.data, _max.to_i)
               _results_count = _results_count +  _lrecord.length
               record = record.concat(_lrecord)
               is_in_cache = true
             else
               is_in_cache = true
             end
           elsif _lxml.status == LIBRARYFIND_CACHE_EMPTY
             is_in_cache = true
           end
         end
      end

See what I did?  I’m sure you do.  However, I didn’t until last night when I thought that the caching service was running really slow.  So I looked in the code, and found my problem.  A typo.  It should have looked like:

      #======================================================
      # Check to see if data was cached -- if it is load
      #======================================================
      if _search_id != nil
         _lxml = CachedSearch.retrieve_metadata(_search_id, _collect.id, _max.to_i)
         if _lxml != nil
           if _lxml.status == LIBRARYFIND_CACHE_OK
             if _lxml.data != nil
               _lrecord =  _objRec.unpack_cache(_lxml.data, _max.to_i)
               _results_count = _results_count +  _lrecord.length
               record = record.concat(_lrecord)
               is_in_cache = true
             else
               is_in_cache = true
             end
           elsif _lxml.status == LIBRARYFIND_CACHE_EMPTY
             is_in_cache = true
           end
         end
      end

Since Ruby, like many scripting languages, happily created variables for you, I didn’t notice it.  And since the program kept running — abiet, more slowly — it didn’t dawn on me that I’d caused a boo-boo.  It wasn’t until last night, 2 days later, that I found it while doing a code audit.  A practice I have when dealing with scripting languages is to audit modified code weekly to inventory the life of each variable/process.  It’s something I do mostly as a way to eliminate variable useage — but in this case, it helped me find this problem.  Ack.

–TR