Basic HTML version of Foils prepared Sept 20 97

Foil 13 Soft Symbol Table References - I

From Perl5 and Advanced Perl4 Features Computational Science for Information Age Course CPS616 -- Sept 20 97. by Geoffrey C. Fox,Nancy McCracken,Tom Scavo


One of Perl's "problems" (also its strength if you are knowledgeable) is that one often needs to understand implementation issues to use effectively
Every package has a symbol table (i.e. a list of used symbols) called :: so that main symbol table is
%main:: and variable $var in main has symbol table entry $main::{'var'}
*var is equivalent to $main::{'var'}
The symbol $original exists, we can set
*var = *original; # and then $var is another 'name' for $original and @var is another name for @original, etc.
  • That is, $var @var %var have same symbol table entry but will have different hard references



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