_You can follow along with the video course from here._ ### Introduction In the previous lesson, we integrated the `SimpleStorage` code directly into the `StorageFactory` contract. This allowed `StorageFactory` to have full access to the `SimpleStorage` contract’s functionality. In this lesson, we will explore a more efficient way to arrange and organize the code by using the **`import`** statement. ### Importing code The `import` keyword enables a contract to utilize code from other files without needing to include the entire codebase directly within the contract. Here are two of the main advantages that the `import` keyword provides: 1. **No cluttering**: it prevents your current file from being cluttered with numerous lines of code, keeping it clean and organized. 2. **Simplified maintenance**: by keeping the code in separate files, it becomes easier to maintain and update individual components without affecting the entire codebase. For example, if we change some lines inside `SimpleStorage`, we would have also to constantly copy-paste the modified content into `StorageFactory` You can now remove the previously added `SimpleStorage` code and replace it with the `import` shorthand: ```solidity import "./SimpleStorage.sol"; ``` > 🚧 **WARNING**:br > All the solidity contracts should be compiled together using the _same compiler version_. It's important to ensure **consistency** between compiler versions across files since each one will have its own `pragma` statement. ### Named Imports Let's assume for a moment that `SimpleStorage` would contain multiple contracts, e.g. `SimpleStorage`, `SimpleStorage1`, `SimpleStorage2`, which are quite extensive in size. If we import the whole file as we did before, the statement will replace the `import` directive with _all_ the code contained in `SimpleStorage.sol`. This will result in an unnecessary expensive deployment of the `StorageFactory` contract. This can be prevented with **named imports**, which allow you to selectively import only the specific contracts you intend to use: ```solidity import { SimpleStorage } from "./SimpleStorage.sol"; ``` You can also use named imports to import multiple contracts: ```solidity import { SimpleStorage, SimpleStorage1 } from "./SimpleStorage.sol"; ``` > 👀❗**IMPORTANT**:br > Try to always default to named imports instead of importing the entire file. ### Conclusion The import keyword allows a contract to use code from other files without including the entire codebase. However, it can introduce compilation issues if different compiler versions are used in these files. ### 🧑‍💻 Test yourself 1. 📕 What's a named import and what are the advantages of using it? 2. 📕 In which way the `pragma` keyword can cause issues while using the `import` statement? Make 2 examples.