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Short-circuited Perl grep

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To check the existence of an element in a Perl array with specific properties, one tends to use `grep`. But this is inefficient because `grep` always checks each element. (Even in scalar context it returns the number of matching elements.) The following function aborts after the first find.

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  1. # Short-circuited grep in scalar context, which returns 1 if an element of the
  2. # passed list is evaluated to true by the anonymous subroutine, without
  3. # continuing after one has been found.
  4. # -> Anonymous test subroutine operating on $_
  5. #    List to test
  6. # <- 1 if an element matched, 0 otherwise
  7. sub shortgrep(&@)
  8. {
  9.   my $test= shift @_;
  10.   for (@_) {
  11.     return 1 if &$test;
  12.   }
  13.   return 0;
  14. }
  15.  
  16. # simple example usage, made possible by prototype:
  17. if( shortgrep { $_->{"entry"} eq "value" } @arrayofhashes ) {
  18.   ...
  19. }
  20. # "sub" and parentheses are still needed in more complex expressions:
  21. if( shortgrep(sub { $_ == 4 }, @ary) && $othercondition ) {
  22.   ...
  23. }

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