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  1. Path: sparky!uunet!dtix!darwin.sura.net!mips!sdd.hp.com!usc!news!netlabs!lwall
  2. From: lwall@netlabs.com (Larry Wall)
  3. Newsgroups: comp.lang.perl
  4. Subject: Re: Assoc array indirection
  5. Message-ID: <1992Aug17.170850.13766@netlabs.com>
  6. Date: 17 Aug 92 17:08:50 GMT
  7. References: <1992Aug17.100513.9649@nuscc.nus.sg>
  8. Sender: news@netlabs.com
  9. Organization: NetLabs, Inc.
  10. Lines: 40
  11. Nntp-Posting-Host: scalpel.netlabs.com
  12.  
  13. In article <1992Aug17.100513.9649@nuscc.nus.sg> ccechk@nuscc.nus.sg (Heng Kek) writes:
  14. : #!/usr/bin/perl
  15. :   %ipaddr = ('nusunix1','137.132.73.11',
  16. :              'nusunix2','137.132.10.11',
  17. :              'nusunix3','137.132.91.12'
  18. :             );
  19. :   @host   = ('nusunix1',
  20. :              'nusunix2',
  21. :              'nusunix3'
  22. :             );
  23. : print eval "\@ipaddr{@host[0..1]}";              # no go
  24. : print eval "\@ipaddr{join(',', @host[0..1])}";  # no go
  25. : print eval "\@ipaddr{$host[0], $host[1]}";      # okay
  26.  
  27. This only works accidentally because all your host names happen to
  28. be identifiers, which when parsed are interpreted as unquoted strings.
  29.  
  30. : Why doesn't the 1st 2 print()s do what I expect?
  31.  
  32. Because you aren't interpolating a comma between the two host names.
  33.  
  34. : How do I achieve my goal, given my intentions in:
  35. : 
  36. : print eval "\@ipaddr{join(',', @host[0..1])}";  # no go
  37.  
  38. Why do you quote the first @ and not the second?  Try
  39.  
  40.     print eval "\@ipaddr{\@host[0..1]}";
  41.  
  42. or better
  43.  
  44.     print eval '@ipaddr{@host[0..1]}';
  45.  
  46. or even better
  47.  
  48.     print @ipaddr{@host[0..1]};
  49.  
  50. Why do you need the eval?
  51.  
  52. Larry
  53.