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Dependency
Injection
v4
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@nicolasgrekas
SensioLabs
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Symfony 4?
By the end of
November 2017
Will requirePHP 7.1
You canuse v3.4 meanwhile
@nicolasgrekas
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The Symfony Core Team Wish!
• Semantic Versioning
• The Backward Compatibility Promise
• @trigger_error(…, E_USER_DEPRECATED);
• etc.
@nicolasgrekas
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Symfony 4 spirit
Automate your config
By defining your own conventions
and the exceptions to the rules
@nicolasgrekas
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services:
_defaults:
autowire: true
autoconfigure: true
public: false
App\:
resource: ../src
config/services.yaml
@nicolasgrekas
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services:
_defaults:
autowire: true
autoconfigure: true
public: false
App\:
resource: ../src
Every class in src/ is potentially a service
@nicolasgrekas
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services:
_defaults:
autowire: true
autoconfigure: true
public: false
App\:
resource: ../src
But every unused service should be cleaned up
@nicolasgrekas
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services:
_defaults:
autowire: true
autoconfigure: true
public: false
App\:
resource: ../src
Every class extending Command
should be tagged with « console.command », etc.
@nicolasgrekas
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services:
_defaults:
autowire: true
autoconfigure: true
public: false
App\:
resource: ../src
Every service needing a LoggerInterface
should be provided with the default logger, etc.
@nicolasgrekas
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services:
_defaults:
autowire: true
autoconfigure: true
public: false
App\:
resource: ../src
Every service needing a LoggerInterface
should be provided with the default logger, etc.
@nicolasgrekas
The default logger is the service that is
named LoggerInterface
(it used to be the one that implements
it, but that was a foot gun)
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DI v4 1/3
- FQCN service ids (case sensitive ids and parameters)
- Private all the things (applies to Symfony core+bundles!)
- Autoconfiguration by interfaces
- Autowiring by service identifier
@nicolasgrekas
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What if I want my own
(extra) conventions?
@nicolasgrekas
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services:
_defaults:
autowire: true
autoconfigure: true
public: false
App\:
resource: ../src
config/services.yaml
@nicolasgrekas
Defaults apply to all services
in this very file only
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@nicolasgrekas
Custom autowiring (re)configuration?
services:
#...
App\MyFooInterface:
alias: App\MyFoo
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@nicolasgrekas
Partial wiring? Named args to the rescue
services:
#...
App\Foo:
arguments:
$defaultLocale: %kernel.locale%
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@nicolasgrekas
Custom autoconfiguration?
services:
_defaults:
autowire: true
autoconfigure: true
public: false
_instanceof:
App\MyFooInterface:
tags: [foo]
App\:
resource: ../src
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services:
_defaults:
autowire: true
autoconfigure: true
public: false
bind:
$defaultLocale: %kernel.locale%
App\:
resource: ../src
@nicolasgrekas
Custom binding for a named argument?
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services:
#...
App\FooConsomer:
arguments:
- !tagged foo
@nicolasgrekas
Inject all services with the « foo » tag?
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services:
#...
_instanceof:
App\MyFooInterface:
tags: [foo]
App\FooConsomer: [!tagged foo]
@nicolasgrekas
Inject all services with the « foo » tag?
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services:
#...
App\FooConsomer:
arguments:
- '%env(file:API_KEY_FILE)%'
@nicolasgrekas
Read a secret from a file?
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DI v4 2/3
- File-local defaults
- By-name and by-type arguments
- By-name and by-type bindings
- !tagged lazy-collections
- Allow processing env vars
@nicolasgrekas
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What about
performances?
@nicolasgrekas
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Hey, Symfony uses
a compiled container!
@nicolasgrekas
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Lazyness everywhere
• On-demand service instantiation
• Service iterators
• On-demand service factories
• Service locators
@nicolasgrekas
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What about performance?
• Short lived processes
vs
• Long lived processes
@nicolasgrekas
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Long lived kernel challenges
• Stateless services
done for core, fix your services
• Resettable services
• Resilient services
community work pending
@nicolasgrekas
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#app/config/config.yaml
parameters:
container.autowiring.strict_mode: true
container.dumper.inline_class_loader: true
@nicolasgrekas
Pro-tip when migrating to 3.4
Opt-in for Symfony 4 behavior
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Symfony 4 wish
Keep you at coding
as long as possibe
@nicolasgrekas
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DI v4 3/3
- Inject services as arguments into actions
- ServiceSubscriberInterface (<3 for service locators)
- PHP configuration
- @required
- Kernel implements CompilerPassInterface
- Resettable services
@nicolasgrekas
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Symfony 4 Summary
It scales with you and your needs, up to the sky
• Built for containers
• Scales to any app (RIP Silex)
• Automates all the things
• Lower entry bar
• Higher dev efficiency
• Performance ++
@nicolasgrekas
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Enjoy
Thank you
@nicolasgrekas
joind.in/22877