Re: [RFC] switch expression

Hello together, Am 25.03.20 um 16:46 schrieb Larry Garfield: > On Wed, Mar 25, 2020, at 10:29 AM, Ilija Tovilo wrote: >> Thanks for your feedback, Larry! >> >>> One possible improvement to either version is allowing an expression on the left side. >>> That is, rather than doing an equality match, do a boolean match. >> >> This is how Rust does it: >> >> ```rust >> let x = match ... { >> Some(y) if y < 5 => ... >> } >> ``` >> >> In other words, you can add an additional guard to each case that >> excepts any expression. We don't really benefit a lot from that since >> we don't have pattern matching. I don't think this would add any >> significant benefit over: >> >> ```php >> $x = true switch { >> $x !== null && $x < 5 => ... >> } >> ``` > > Good point, I'd forgotten about that potential trick. So as long as an expression is > allowed on the left, rather than just a literal, which is then == compared against the provided > value, that should be "good enough" for most use cases. > > The implementation should include some tests to make sure that works properly, but I'm > happy with the resulting syntax. > > So then the net result is: > > $var = switch($val) { > case expr1 => expr2; > } > > Where $val gets compared against the result of each expr1, and if true then $var is set to > expr2. on the first glance this all looks nice but you actually created something more like an if-expression that uses switch as a keyword because you stripped switch of some of its major features: - you compare the given value to possible cases -> you compare expressions to true - you can fall through to other cases without break - what about the default case? What about the following if-expression-syntax: $var = if ($x > 0) { return 1; } elseif ($x < 0) { return -1; } else { return 0; } Maybe this is more in line of what you want to do with your switch expression? Greets Dennis