# 03 - Shared Module Architecture: expect/actual, Interfaces and Dependency Injection

The expect/actual mechanism in Kotlin allows declaring an API in common code and providing platform-specific implementations for each target without breaking encapsulation. Combined with Koin for multiplatform dependency injection, shared logic can be tested in isolation.

## What you'll learn

- Architettura a layer per il modulo condiviso: domain, data, presentation
- expect/actual: pattern corretti e anti-pattern da evitare
- Interfacce per isolare dipendenze platform-specific
- Koin per dependency injection multiplatform
- Testing del modulo condiviso in isolamento

*This article is part of the **Kotlin Multiplatform** series on federicocalo.dev.*

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## Read the full article

The complete article (13 min read) with code examples, diagrams, and practical exercises is available here:

**➡️ [03 - Shared Module Architecture: expect/actual, Interfaces and Dependency Injection](https://federicocalo.dev/en/blog/kmp-shared-module-expect-actual-dependency-injection)**

`https://federicocalo.dev/en/blog/kmp-shared-module-expect-actual-dependency-injection`

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*By [Federico Calò](https://federicocalo.dev) — Software Developer & Technical Writer*