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Dependency Injection David Frame of 31interactive

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Scenario #1 We need to be able to test our order class without sending any emails!

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Dummy mailer class with a send() method that does nothing!

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What is dependency injection?

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Single Responsibility Principle a class should have only a single responsibility Open / Closed Principle “software entities … should be open for extension, but closed for modification.” Liskov Substitution Principle Interface Segregation Principle Dependency Inversion Principle one should “Depend upon Abstractions. Do not depend upon concretions.”

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Scenario #2 We need to store emails in the database so they can be queued up and sent at a later date!

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Dependency Injection Containers

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Thanks for listening! Any questions? :) Email: [email protected] Twitter: @DaGrFr Review this talk at https://joind.in/16984