Why doesn't the flip-flop operator work in all scalar contexts? It works fine when looping over a file handle:

while(<$fh>)
{
  next  if 1..1; # skip first line
  print;
}

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But it doesn't seem to work at all in other kinds of loops:

# intentionally not using range operator to avoid confusion
for(1,2,3,4,5) 
{
  next  if 1..1; # never returns true!
  print "$_\n";
}

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my $i = 0;
while(++$i <= 5)
{
  next  if 1..1; # never returns true!
  print "$i\n";
}

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Both of those examples print the numbers 1 through 5, rather than skipping 1 and just printing 2 through 5.

The docs for perl 5.10 don't seem to indicate that it only works in the context of file handles. From perldoc perlop:

In scalar context, ".." returns a boolean value. The operator is bistable, like a flip-flop, and emulates the line-range (comma) operator of sed, awk, and various editors. Each ".." operator maintains its own boolean state. It is false as long as its left operand is false. Once the left operand is true, the range operator stays true until the right operand is true, AFTER which the range operator becomes false again. It doesn't become false till the next time the range operator is evaluated.

It just says "in scalar context," not "in scalar context if and only if you're looping over a file handle's records." Bad docs? Bad implementation? What am I missing?

In reply to Why doesn't the flip-flop operator work in all scalar contexts? by siracusa

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