Console output in services

[jbieliauskas]

Some commands use services, which require OutputInterface to print messages to console. A common pattern is to do this:

In a service:

class SomeService
{
    public function doSomething(): void
    {
        // code...
        $this->output->writeln('Message');
    }

    public function setOutput(OutputInterface $output): void
    {
        $this->output = $output;
    }
}

And in a command:

class MyCommand extends ContainerAwareCommand
{
    protected function execute(InputInterface $input, OutputInterface $output)
    {
        $service = $this->getContainer()->get('some.service');
        $service->setOutput($output);
        $service->doSomething();
    }
}

However, there's nothing special about the $output in a command. The service can instantiate one itself (as does Symfony by just newing-up a ConsoleOutput). This would eliminate the need for a setter, our services would become self-containing, the command would lose extra lines of code.

Furthermore, do not wrap calls to $this->output in a private method if the private method simply forwards a call to $this->output.

❌ This is bad:

class MyService
{
    public function doSomething(): void
    {
        // code...
        $this->doOutput('Message');
    }

    public function doOutput(string $message): void
    {
        $this->output->writeln($message);
    }
}

✅ This is good:

class MyService
{
    public function doSomething(): void
    {
        // code...
        $this->output->writeln('Message');
    }
}