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IoC DI

A small IoC Dependency Injector and Service Locator with experimental features, including a Data Locator.

Use

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Basic

Service Locator injection of "NameInterface" typed parameter into newly constructed "Creature"

Mixing Service Locator And Provided Parameters

Sometimes it is useful to allow the ServiceLocator to find one parameter, to but provide another parameter instead of using the ServiceLocator for it.

Defaults

If the DependencyInjector can't resolve a dependency, you can provide a fallback default for the parameter.

Because it may be undesirable to first instantiate a default prior to it being used, special classes are available to prevent pre-instantiation.

These special classes include

• \Grithin\IoC\Service
• \Grithin\IoC\Datum
• \Grithin\IoC\Call
• \Grithin\IoC\Factory

See the Special Types

Special Types

Using Grithin\IoC\SpecialTypeInterface

Service Object

Used by: SL, DI

• If you want to point to a service with options.
• If you want to provide a parameter default as an object, but don't want to instantiate the object unless it is for default

Example of using Service for a default

Datum

Used by: SL, DI

• If you want configure a service to be instantialized using datum that might be set later or change

Call

Used by: SL, DI, DL

• If you want to point to the result of some callable.

Factory

Used by: SL, DI, DL

• Used to indicate to DataLocator it should use thing as a factory.

Whereas, with Call, a datum will be resolved by calling, with Factory, it will be resolved by calling every time the data is accessed from the DataLocator

Resolution Of Parameters

For some method definition, how does the injector resolve the injection values?

• if with variant/option is used (call_with and call(..., ['with'=>[]])), use with array
  • by position
  • by name
• by type declaration (ServiceLocator)
• if parameter starts with uppercase, attempt to match against
  • Service
  • Datum
• if defaults option is present, use it
• use the default provided in the method/constructor definition

Parameter Name Based Resolution

As a shortcut for well-known frequently used expected parameters, injection can use the name alone so long as that name starts with a capital letter. And, in this case, both services and data are checked.

Static analysis and autocompletion within editors has made this usually a bad option.

ServiceLocator

Beyond The Basics

Singleton

For something like a Database, it is desirable that only one primary instance be created.

You can also just provide an existing singleton object to the ServiceLocator

Links

It may be useful to link one service id to another service

Special Types

It may be useful to resolve a service using a special type.

Here, a function is used to get a service

Using Service for special configuration

Data Locator

A service locator for data.

Notes

By default, SL does not check all classes to resolve an interface or abstract class, it only checks what is within the services (by id) or available without further file inclusion. You can make it check everything though: