I notice that LLMs have a strange way of writing perl.
(strange until you learn it !)
Chaining ternary operators
these seem to be used in places where i would have been more familiar with a simple if/then/else conditional. This one‑liner is useful when you need to assign a value based on a series of mutually exclusive tests without writing explicit if/elsif/else blocks.
Chaining ternary operators for compact conditionals
my $age = 27;
my $category = $age < 13 ? 'child'
: $age < 20 ? 'teen'
: $age < 65 ? 'adult'
: 'senior';
print "Category: $category\n";
# Determine a short label for a set of unrelated inputs
my $label = $age < 13 ? 'child'
: $color eq 'red' ? 'stop'
: $count == 0 ? 'empty'
: $mode eq 'debug' ? 'verbose'
: $size > 1000 ? 'big'
: 'default';
- When condition is true, the part after the question‑mark, becomes the value of the whole expression.
- if true, The rest of the chain (other ternary tests) are never evaluated. also including the last return value is also skipped, in this case.
- therefore, ordering matters.
- finally, The final
:supplies the fallback value, acting as the “else” case. - you must be able to read it easily, but it provides terse syntax.
- Alternatives: if this isnt appropriate for your usecase, then alternatives are: given/when, hash lookup, or simple if/else .
an extra value can be appended to the right side to return a specific false value.
otherwise, it is implied that testing false will be handled/passed by/to the next ternary in the chain.
use strict;
use warnings;
my $score = 78; # try different values
my $result =
$score >= 90 ? 'A: Excellent' :
( $score < 90 ? 'Not an A, keep trying' :
$score >= 80 ? 'B: Good' :
( $score < 80 ? 'Not a B, try harder' :
$score >= 70 ? 'C: Satisfactory' :
( $score < 70 ? 'Not a C, improve' :
$score >= 60 ? 'D: Pass' :
( $score < 60 ? 'F: Fail – below passing mark' :
'??' ) ) ) );
print "$result\n";
note:
Operator precedence – The ternary operators (? and :) bind loosely, so you often need parentheses when mixing them with other operators.
example:
$result = $a > $b ? $a : ($c < $d ? $c : $d);
advanced theoretical use:
Chaining (nesting) ternary operators
Because a ternary expression itself returns a value, you can place another ternary where either the true or false part belongs:
cond1 ? expr1
: cond2 ? expr2
: cond3 ? expr3
: expr4;
