Compile contracts¶

Location¶

All of your contracts are located in your project's contracts/ directory. As contracts are written in Solidity, all files containing contracts will have a file extension of .sol. Associated Solidity libraries will also have a .sol extension.

Command¶

To compile a Truffle project, change to the root of the directory where the project is located and then type the following into a terminal:

truffle compile

Upon first run, all contracts will be compiled. Upon subsequent runs, Truffle will compile only the contracts that have been changed since the last compile. If you'd like to override this behavior, run the above command with the --all option.

Build artifacts¶

Artifacts of your compilation will be placed in the build/contracts/ directory, relative to your project root. (This directory will be created if it does not exist.) The name of the generated artifact .json files do not reflect the name of the source file but the name of the contract definition. This means that changing the contract name string in the artifacts.require method to match that of the source file may lead to a Error: Could not find artifacts for {yourContract} from any sources if the contained smart contract definition is named differently.

These artifacts are integral to the inner workings of Truffle, and they play an important part in the successful deployment of your application. You should not edit these files as they'll be overwritten by contract compilation and deployment.

Dependencies¶

You can declare contract dependencies using Solidity's import command. Truffle will compile contracts in the correct order and ensure all dependencies are sent to the compiler. Dependencies can be specified in two ways:

Importing dependencies via file name¶

To import contracts from a separate file, add the following code to your Solidity source file:

import "./AnotherContract.sol";

This will make all contracts within AnotherContract.sol available. Here, AnotherContract.sol is relative to the path of the current contract being written.

Note that Solidity allows other import syntaxes as well. See the Solidity import documentation for more information.

Importing contracts from an external package¶

Truffle supports dependencies installed via NPM. To import contracts from a dependency, use the following syntax

import "somepackage/SomeContract.sol";

Here, somepackage represents a package installed via NPM, and SomeContract.sol represents a Solidity source file provided by that package.

For more information on how to use Truffle's package management features, please see the Truffle NPM documentation.