The Easy LifeInversion of Control with StructureMap

Brad Tutterow

www.twitter.com/codebadger

www.smips.com/smip/blogs/codebadger

What is a dependency?

Any thing the code I’m working on needs to work that is not the code I’m working

on

Database File System Web Content

Services Email Other Code

Our Problem SpaceTIME TO USE YOUR IMAGINATION

SprocketStore

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Get the current market price for a sprocket

Check for a quantity discount

Return the final price

Get the current market price for a sprocket

Call the Sprocket Market web service

Check for a quantity discount

Look it up in the sales database

Return the final price

Multiply the discount price by the quantity requested

“High-level modules should not depend on low-level modules. Both should depend on

abstractions.”

Dependency Inversion Principle

“High-level modules should not depend on low-level modules. Both should depend on

abstractions.”

Are dependencies bad?

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Rigidity

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FragilityFragility

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Immobility

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“High-level modules should not depend on low-level modules. Both should depend on

abstractions.”

Dependency Inversion Principle

SprocketStore

SalesDatabase

SprocketStore

SalesDatabase

ISalesDatabase

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EasierMaintenance

Testability

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Here we go!

Dependency Injection

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