> On Feb 19, 2020, at 2:00 PM, Bishop Bettini <bis...@php.net> wrote:
>
> Consequently, the only way to safely initialize class constants and static
> members is at run-time, and I can only think of one way to do it. Apologies
> if this has already been suggested: taking a cue from C#, a static class
> constructor ([1]) would allow us to have expression-initialized constants
> and static members.
>
> <?php
> class Config {
> public const URL = null; // compile time initialization
> protected static $mtime = null; // compile time initialization
> private static function __constructStatic() {
> $env = json_decode(file_get_contents('config.json'));
> self::URL = $env->url;
> self::$mtime = filemtime('config.json');
> }
> public function reload() {
> if (self::$mtime < filemtime('config.json'))
> self::__constructStatic();
> }
> }
> }
>
> echo Config::URL; // assert: runtime has already called _constructStatic
> $config = new Config; // assert: __constructStatic called only once by
> runtime
> $config->reload(); // instance may call its own static constructor
> ?>
>
> Trying to do the same for global constants, static variables, or function
> default parameters resists a similar initialization mechanism because we
> don't have defined common entry point analogues. If we had a main(), or if
> we had framed @before decorators, we could do something similar, but we
> don't -- so I feel we should leave these off the table.
For different reasons than this RFC I have wanted a static class constructor
for a really long time.
I hope this is something we can seriously consider. Thanks Bishop for
proposing it.
-Mike
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