Hi, Tyson, Thanks.
---- En dom, 09 ago 2020 16:41:44 +0200 tyson andre <tysonandre...@hotmail.com> escribió ---- > Hi Internals, > > To be clear: The variables in the top-level scope depend on what has > require()d/include()d a file. > The top-level scope starts off as being global, but if a file is required > from within a function/method/closure (e.g. the autoloader closure), then > the top-level scope in the require()'d file uses variables (e.g. $this) from > whatever context called require(). My idea was using 'use vars' not only with global vars but also with vars in context. > It may be possible to use a declare syntax, e.g. > declare(used_variables='all') for `'all'`, `null`, `['var1', 'var2']`, etc. > - Otherwise, you face the issue of where `use vars` should be allowed, what > happens if there's a statement before `use vars`, etc. Good point, I don't think about that. > I can see this as having some use cases, such as in configuration files or > files used for bootstrapping. > For example, > > ``` > <?php > declare(used_variables=null); > > $api_base = IS_PRODUCTION ? 'https://example.com/api/' : > 'http://localhost/api'; > do_stuff(); > > return [ > // long config array > 'url_new' => "$api_base/new", > 'url_all' => "$api_base/all", > ]; > ``` > > This feature (ignoring the question of syntax) would ensure that people > reading the file knew that $api_base was not modified by other files > and that other files did not read local variables created within a > configuration/bootstrapping file in unexpected ways, > which is a fairly common issue in some web apps I've worked on. > Opcache would also do a better job at optimizing code if it knew which > variables in a top-level scope couldn't be modified. > > That being said, there's been opposition to extensions to the language that > add functionality that can be implemented in other ways, as in Rowan's > comment, > but peoples opinions depend on the specifics of the proposal > (e.g. `match` was added and was more performant than chained conditionals or > switch). > > As Rowan said, there are ways to reimplement this: > - Wrapping the config file or bootstrapping file in a closure, global > function, or class method > - `function safe_require_once(string $path, $vars = []) { extract($vars); > require($path); }` from the caller, to limit what variables are passed in. > IDEs/tooling would be worse at telling you if a file name had a typo, though. I think in views system( of some frameworks ) or CMS like WordPress. In WordPress, for example, I can do something like this: ## index.php ``` foreach($posts as $post ) { $post = 'foo'; } ``` index.php is loaded from CMS. $post is a global variable used in WordPress core. So that, I am crashing WordPress. However, with: ``` use vars none; foreach($posts as $post ) { $post = 'foo'; } ``` I don't crash my WordPress or any external plugin which can use global vars. My file now is a container( black box ) where my code is isolated. Regards -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: https://www.php.net/unsub.php
