Local Service Binding

Introduction

Since Symfony 4.0 autowiring scalar arguments has been simplified with local binding:

Syntax

Pre Symfony 4.0

services:
    _defaults:
        autowire: true
        autoconfigure: true
        public: false
 
    App\Some\Service1:
        $projectDir: '%kernel.project_dir%'
 
    App\Some\Service2:
        $projectDir: '%kernel.project_dir%'
 
    App\Some\Service3:
        $projectDir: '%kernel.project_dir%'
 

Post Symfony 4.0

services:
    _defaults:
        autowire: true
        autoconfigure: true
        public: false
        bind:
            $projectDir: '%kernel.project_dir%'
 

Explicitly define injection services

# when services created/defined in this file inject 'BarInterface',
# use the '@normal_bar_service' ...
services:
  _defaults:
    bind:
      BarInterface: "@normal_bar_service"
 
  # ... except for this particular service, which uses a different service
  Foo:
    bind:
      BarInterface: "@special_bar_service"