Comparison chain View as Markdown

Andrea Faulds wrote on 05/12/2014 14:47:

Hi!

I followed by https://wiki.php.net/rfc/howto and I would like to propose a concept "comparison chain" to implementing to future PHP versions.
It would be very usable if PHP can do that in python-style.

Thank for your attension!
Are you saying to allow (1 < x < 2) etc.? That would be nice, although it’s a backwards-compatibility break as currently (1 < x < 2) would do something different, as would, say, ($x == $y == $z).

For those of us that don't know Python, an explanation might be handy.
From a quick search, this StackOverflow answer sums it up quite nicely,
assuming it's correct: http://stackoverflow.com/a/25753528/157957

So, "$a < $b < $c" would be short-hand for "$a < $b && $b < $c". It
would short-circuit in exactly the same way, and be extended to any
number of comparison operators.

The obvious use case is for maths style "is between" notation, e.g. if (
10 < $total <= 100 )

Is this correct, a) for Python, and b) for what is suggested for PHP?

As Andrea notes, it would be a backwards compatibility, although the
chances of anyone deliberately using a boolean as operand to a < or >
are unlikely, and that's what's currently implied by $x < $y < $z.
Perhaps if == was left out of the mix, so that $x == $y == true would
evaluate the same way it does now, that might be a working compromise?

Regards,

Rowan Collins
[IMSoP]

Hi!

I followed by https://wiki.php.net/rfc/howto and I would like to
propose a concept "comparison chain" to implementing to future PHP versions.
It would be very usable if PHP can do that in python-style.

Thank for your attension!

Are you saying to allow (1 < x < 2) etc.? That would be nice, although
it’s a backwards-compatibility break as currently (1 < x < 2) would do
something different, as would, say, ($x == $y == $z).

Comparisons are non-associative in PHP 1, so something like $x == $y ==
$z is currently invalid code. As such this would not break compatibility.

Nikita