Introduction to rg\injection

rginjection Bastian Hofmann

Questions? Ask!

Dependency Inversion

http://www.doolwind.com/blog/solid-principles-for-game-developers/

Dependencies

Dependency Injection

Constructor

Setter

Method argument

Constructing classes

Make it easier with factories

Dependency Injection Container

What‘s out there?

<?xml version="1.0" ?> <container xmlns="http://symfony-project.org/2.0/container"> <parameters> <parameter key="mailer.username">foo</parameter> <parameter key="mailer.password">bar</parameter> <parameter key="mailer.class">Zend_Mail</parameter> </parameters> <services> <service id="mail.transport"class="Zend_Mail_Transport_Smtp" shared="false"> <argument>smtp.gmail.com</argument> <argument type="collection"> <argument key="auth">login</argument> <argument key="username">%mailer.username%</argument> <argument key="password">%mailer.password%</argument> <argument key="ssl">ssl</argument> <argument key="port">465</argument> </argument> </service> <service id="mailer" class="%mailer.class%"> <call method="setDefaultTransport"> <argument type="service" id="mail.transport" /> </call> </service> </services></container>

rginjection inspired by google-guice http://code.google.com/p/google-guice/

Creating an instance of a class

Automatic creation of dependencies through Typehints

@inject

What classes can be injected?

No constructor

Constructor without arguments

Constructor with arguments that have default values

Injectable constructor

By the way: Property Injection

Singletons with public static getInstance method following the same rules

STOP: Don‘t use Singeltons

Singletons are evil!

Let the DIC take care of instances

@singleton

By the way...

Passing additional, ﬁxed values to instance

What about testing

Only test the class, not the dependencies

Mocking

Working with Interfaces

Why interfaces?

But we can not create an instance of an Interface!

@implementedBy

Mocking an interface

Named @implementedBy

What‘s that for?

Providers

@providedBy

Method invocation at DIC

Same rules

And if you don‘t like annotations...... or want to integrate 3rd party code

Integrate it into your framework

Great! So, how does it work internally?

Development: Reﬂection

Production: Generated Factory Classes

Available? very soon

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Introduction to rg\injection

by Bastian Hofmann on Feb 07, 2012

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