[9.x] Helper - Set tag on object based on instanceof

[wimulkeman]

Purpose

Allow tagging an object based on its parent(s), interface(s) or its own FQCN.

This enables a developer to tag multiple objects dynamically at once without having to manually add new objects when they are added and extend a certain interface or parent.

Dynamically tagging can be an useful addition when you use a strategy pattern in your code and want, for example, register a new handler.

How is it used

Its usage would result in line with the following sample code.

tag_instance_of(BaseServiceTypeInterface::class, 'my-tag');

$this->app
    ->when(MyDynamicHandlerService::class)
    ->needs(BaseServiceTypeInterface::class)
    ->giveTagged('my-tag');

// ...

class MyDynamicHandlerService
{
    public function __construct(BaseServiceTypeInterface ...$handlers)
    {
        $this->handlers = $handlers;
    }

    public function handle(string $type, array $config)
    {
        foreach ($this->handlers as $handler) {
            if (! $handler->supports($type)) {
                continue;
            }

            return $handler->handle($config);
        }

        throw new \LogicException('Missing handler for type '.$type);
    }
}

Configuration options

The developer can influence certain parts by configuration:

• app.instance_of.cache (bool) - Wether or not to cache the result of the tagging. This can be used in non-development environments to speed-up the proces.
• app.instance_of.namespaces.include (string[]) - The class namespaces that should be considered to be tagged. By default this is only done for App\.
• app.instance_of.namespaces.exclude (string[]) - The class namespaces that should be ignored to be tagged. By default this one is empty.
• app.instance_of.classmap (array<string, string[]> - A custom created classmap. By default a classmap and the classes and interfaces it implements/extends are created based on the Composer classmap.

Based on
This MR is a rework of #44164. In this MR the functionality has been moved to a user land function and the codebase has been updated to boost its performance (the result of running it in production environments).

This update has been inspired by the Symfony methology to tag services through an instanceof provided value. @see https://symfony.com/doc/current/service_container/tags.html#autoconfiguring-tags

Resolves #42499

[ankurk91]

It is a huge function.
It will be rarely used.
It can go into a dedicated class instead.

[wimulkeman]

In which namespace does that need to go if it would not be a function? I would say that it would sit in Illuminate\Container with something like TagInstance as classname. Or perhaps as a trait which developers can set upon their Application?

[taylorotwell]

Since it looks like this entire thing can be done in user-land, I would suggest releasing this as a Composer package. That way the functionality can be shared with others but we don't have to maintain it in the core. 👍

[luninroman]

Since it looks like this entire thing can be done in user-land, I would suggest releasing this as a Composer package. That way the functionality can be shared with others but we don't have to maintain it in the core. +1

Such a useful function would never end up in the main package? That's nonsense. Symfony has been using it for years