Perl - how to get the keys of a constant hashref
How do you get the keys of a constant hashref?
$> use constant A => { 1 => 100, 2 => 200, 3 => 300} () $> A { 1 => 100, 2 => 200, 3 => 300 } $> keys A ERROR: Type of arg 1 to keys must be hash (not constant item) at (eval 13) line 3, at EOF $> keys %A () $> (keys %{A}) Ambiguous use of %{A} resolved to %A at (eval 18) line 1, <IN> line 8. ()
All seems lost until you learn that a constant is actually a function. You can leave off the parentheses to call a function in perl, but in this case you have to call the function to make it clear.
$> (keys A()) ERROR: Type of arg 1 to keys must be hash (not constant item) at (eval 16) line 3, near "A()) $> (keys %{A()}) (1, 3, 2)