Perl Style: Never define "TRUE" and "FALSE"

Jan 1, 1998 by Tom Christiansen

• The language understands booleans. Never define them yourself! This is terrible code:

       $TRUE  = (1 == 1);
       $FALSE = (0 == 1);
  
       if ( ($var =~ /pattern/ == $TRUE  ) { .... }
       if ( ($var =~ /pattern/ == $FALSE ) { .... }
       if ( ($var =~ /pattern/ eq $TRUE  ) { .... }
       if ( ($var =~ /pattern/ eq $FALSE ) { .... }
  
       sub getone { return "This string is true" }
  
       if ( getone() == $TRUE  ) { .... }
       if ( getone() == $FALSE ) { .... }
       if ( getone() eq $TRUE  ) { .... }
       if ( getone() eq $FALSE ) { .... }
  

• Imagine the silliness of this progression, and stop at the first one.

       if (    getone() )                       { .... }                   
       if (    getone() == $TRUE  )             { .... }
       if (   (getone() == $TRUE) == $TRUE  )           { .... }
       if ( ( (getone() == $TRUE) == $TRUE) == $TRUE  ) { .... }
  

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Copyright © 1998, Tom Christiansen All rights reserved.