in reply to Re^4: 'state' variables and unit testing (intentional)
in thread 'state' variables and unit testing

Unlike the solution using state the my in an enclosing block allows you to include controlled access to the cache. 

{
 my $_cache;
 sub withLongComputation {
  $_cache //= ...;
  ...
 }
 sub clearCache {
  undef $_cache;
 }
}

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Jenda
Enoch was right!
Enjoy the last years of Rome.

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Re^6: 'state' variables and unit testing (intentional)
by tobyink (Canon) on Feb 04, 2014 at 13:08 UTC

    An an alternative:

    {
   use Scope::Guard;
   my $_cache;
   sub withLongComputation {
      $_cache //= ...;
      ...;
   }
   sub localClearCache {
      my $old = $_cache;
      undef $_cache;
      return guard { $_cache = $old };
   }
}

...;

withLongComputation();
withLongComputation();

{
   my $guard = localClearCache();
   # here, $_cache has been cleared
   
   withLongComputation();
}

# Because $guard has fallen out of scope,
# $_cache has been restored to its old value

withLongComputation();

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    use Moops; class Cow :rw { has name => (default => 'Ermintrude') }; say Cow->new->name
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