On Tue, 15 Dec 2020, 00:30 Andreas Leathley, <a.leath...@gmx.net> wrote:
> I checked in my vendor directory for currently used switch(true) usages,
> there were 96 matches. It is often used when handling an unknown value
> and needing to display or convert it, as there the structure of a switch
> is easier to scan compared to other comparisons like ifs (at least it is
> for me). Compared to match these switch statements are a lot uglier,
> which shows that there are use cases for it even when you are forced to
> use switch.
>
> This is a good example in my estimation, from the Symfony Console Dumper
> class (taken from Symfony 5.2), when a value is converted into a string
> representation:
>
> ```php
> $this->handler = function ($var): string {
> switch (true) {
> case null === $var:
> return 'null';
> case true === $var:
> return 'true';
> case false === $var:
> return 'false';
> case \is_string($var):
> return '"'.$var.'"';
> default:
> return rtrim(print_r($var, true));
> }
> };
> ```
>
> With match this becomes much more concise:
>
> ```php
> $this->handler = function ($var): string {
> return match {
> null === $var => 'null',
> true === $var => 'true',
> false === $var => 'false',
> \is_string($var) => '"'.$var.'"',
> default => rtrim(print_r($var, true)),
> };
> };
> ```
>
> The same with ifs:
>
> ```php
> $this->handler = function ($var): string {
> if (null === $var) {
> return 'null';
> }
> if (true === $var) {
> return 'true';
> }
> if (false === $var) {
> return 'false';
> }
> if (\is_string($var)) {
> return '"'.$var.'"';
> }
>
> return rtrim(print_r($var, true));
> };
> ```
>
> The implied return type for match and the reduced amount of code to scan
> makes match {} much better in my opinion, with ifs you always have to
> make sure there isn't additional logic somewhere, and it makes it easy
> to add more complex code "by accident" compared to match. match (true)
> would be possible now, but the true makes the code a bit confusing,
> while without the (true) it reads more like natural language ("match the
> first possible expression in this list and return a corresponding value").
>
> --
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In OCaml they actually use `function` as a shorthand for lambda + match (on
the implied first argument). `fun` is the lambda keyword (and also `let`).
>
>
