jlttt / sdic

An overview of the main features of the symfony/dependency-injection package.

Depency Injection (Symfony 4.2)

An overview of the main features of the symfony/dependency-injection package.

Usage

Clone the repository:

$ git clone https://github.com/jlttt/sdic.git

Install dependencies:

$ cd sdic 
$ composer install

Run the application:

$ ./bin/deploy

Tags allow to navigate between the different parts. For example, to go to the code of the default application, use:

$ git checkout start

Default Application

Tag: start

The default application without depency injection container. To automate deployment of customer clouds, one ask a CloudProvider service the list of existing clouds (throw an API), select one of them and deploy it thanks to the Jenkins API.

Depency Injection Container

Tag: dependency-injection-container

Basic use of the dependency injection container.

Useful objects and methods:

• Definition: Definition of a service, creation for a FQCN
• Reference: Reference to a service, creation from a service id.
• ContainerBuilder::setDefintion(serviceId, definition) : register a definition
• ContainerBuilder::register(serviceId, fqcn): register a class as definition
• Definition::setArgument(reference): register a dependency (as a service reference) to a definition

Autowiring

Tag: autowiring

Automatic depency injection. Argument setting is no more needed, but container needs to be compiled.

Useful methods:

• Definition::setAutowired: active/unactive autowiring for the service
• ContainerBuilder::compile: Compilation of the container

Autoconfiguration

Tag: autoconfiguration

Exploration of the application to find services (thanks to PSR-4). Require the symfony/config package and the container needs to be compiled.

Useful objects and methods:

• FileLoader,
• FileLoader::registerClasses(baseDefinition, namespace, path): register services of a namespace from a base definition
• Definition::setAutoconfigured: active/unactive autoconfiguration

Configuration file

Tag: config-file

Use the config component to move container configuration in a specific file.

Useful methods:

• FileLoader::load(configFile) : a context with preset variables ($container, $loader,...) is provided to the configuration file

Improve application: add filters

Tag: filter-feature

To go deeper, one needs to extend the initial application by allowing to filter clouds.

Scalar values injection

Tag: scalar-values-injection

Container injects classes. It can also inject scalar values (string, array, int,...).

Useful methods:

• ContainerBuilder::setParameter(id, scalarValue): register a scalar value
• ContainerBuilder::addArgument('%id%'): use a registered scalar value (note that the id is surrounded by %)

Method call

Tag: add-method-call

A service definition can be enhanced by registring method calls to play right after the service instanciation.

Useful methods:

• Definition::addMethodCall(method, arguments)

Tags and compiler pass

Tag: tags-and-compiler-pass

A service definition can be enhanced by registering method calls to play right after the service instanciation.

Useful class and methods:

• CompilerPassInterface : contract for a new compiler pass
• ContainerBuilder::addCompilerPass(compilerPass): register the given compiler pass to be run at compilation time
• ContainerBuilder::registerForAutoconfiguration(fqcn): prepare the autoconfiguration to extract all classes extending fqcn
• ContainerBuilder::findTaggedServiceIds(tag): retrieve services by tag
• Definition::addTag(tag): tag a service

YAML Configuration file

Tag: yaml-config-file

Use Yaml format for configuration file. Require the symfony/yaml package

Useful objects:

• YamlFileLoader

Dump container

Tag: container-dump

The container can be cached to avoid compilation at each application run.

Useful objects and methods:

• PhpDumper::dump(options) : dump as PHP class