Ternary operator change from left-associative to right-associative  🔗

General idea  🔗

Note please see the forecast.

Quoting from phpsadness:

(In PHP) the ternary operator is left-associative and therefore behaves entirely 'incorrectly':

$ cat ternary.php
<?php
echo (FALSE ? "a" : FALSE ? "b" : "c")."\n";
echo (FALSE ? "a" : TRUE ? "b" : "c")."\n";
echo (TRUE ? "a" : FALSE ? "b" : "c")."\n";
echo (TRUE ? "a" : TRUE ? "b" : "c")."\n";
?>

$ php ternary.php
c
b
b
b

In any other language with a ternary operator, you can stack them and build an if-elseif-elseif-else expression:

$ cat ternary.pl
#!/usr/bin/perl -w
use strict;

print +(0 ? "a" : 0 ? "b" : "c")."\n";
print +(0 ? "a" : 1 ? "b" : "c")."\n";
print +(1 ? "a" : 0 ? "b" : "c")."\n";
print +(1 ? "a" : 1 ? "b" : "c")."\n";

$ perl ternary.pl
c
b
a
a

Hurdles to overcome  🔗

There are a couple of big hurdles that would need to be overcome.

How to make the change  🔗

It would not be feasible to solely change the associativity without taking any other steps. This would silently break any code that contains any nested ternaries.

A better plan that allows for a deprecation notice to be generated for at least one minor version of PHP would be required.

An alternative approache might be to use a different symbol.

Break a large amount of existing code  🔗

People would need convincing that breaking existing code would justified by the change in associative rules.

Nested ternary operators are terrible  🔗

Nested ternaries in real code do not look like the 'clean' examples given:

print +(0 ? "a" : 0 ? "b" : "c")."\n";

Instead, when you use actual variable names with them they look much more like this:

print($isBookingBlocked ? "Unavailable" : $hasBeenReserved ? "Reserved" : "Open") . "\n";

Although people who like ternaries may disagree, this code is not easy to read. It requires the reader to accurately parse a line horizontally. It also requires a user to remember multiple things at once, which tends to lead to mistakes.

Using actual if else statements makes the code far easier to read.

$status = "Open";
if ($isBookingBlocked) {
    $status = "Unavailable";
}
else if ($hasBeenReserved) {
    $status = "Reserved";
}

Forecast  🔗

Quite unlikely to happen without a cunning plan.

About the only way this could be addressed would be to use a new symbol for a right associative ternary operator.

To keep the similarity with the current question mark ?, an inverted question mark ¿ could be used. /s

From PHP 7.4 ternaries require parentheses to set the correct order. This would allow us to implement them to be right associative by default if we wanted to.

Notes  🔗

http://phpsadness.com/sad/30