Description

It would be great to define default service definition by trait usage.

This could be a great alternative for some auto-wiring setter like parameters, instead of manual definition.

Concrete case

Here is my KernelRootDirTrait:

trait KernelRootDirTrait
{
    /**
     * @var string
     */
    private $kernelRootDir;

    /**
     * @return string
     */
    public function getKernelRootDir(): string
    {
        return $this->kernelRootDir;
    }

    /**
     * @param string $kernelRootDir
     */
    public function setKernelRootDir(string $kernelRootDir)
    {
        $this->kernelRootDir = $kernelRootDir;
    }
}

And the service:

class MyService
{
    use KernelRootDirTrait;
}

If we could define the default by trait usage like this:

services:
    _trait:
        AppBundle\PropertyTrait\KernelRootDirTrait:
            calls:
                - [setKernelRootDir, ['%kernel.root_dir%']]

With that, the MyService service will automatically have the %kernerl.root_dir% parameter. :-)

The interest of trait is the re-usability of them. This will remove lot of manual parameter definition lines.

What do you think?