Dependencies

Forge manages dependencies using git submodules by default, which means that it works with any GitHub repository that contains smart contracts.

Adding a dependency

To add a dependency, run forge install:

$ forge install transmissions11/solmate Installing solmate in "/private/var/folders/p_/xbvs4ns92wj3b9xmkc1zkw2w0000gn/T/tmp.FRH0gNvz/deps/lib/solmate" (url: Some("https://github.com/transmissions11/solmate"), tag: None) Installed solmate

This pulls the solmate library, stages the .gitmodules file in git and makes a commit with the message "Installed solmate".

If we now check the lib folder:

$ tree lib -L 1 lib ├── forge-std ├── solmate └── weird-erc20 3 directories, 0 files

We can see that Forge installed solmate!

By default, forge install installs the latest master branch version. If you want to install a specific tag or commit, you can do it like so:

$ forge install transmissions11/solmate@v7

Remapping dependencies

Forge can remap dependencies to make them easier to import. Forge will automatically try to deduce some remappings for you:

$ forge remappings ds-test/=lib/forge-std/lib/ds-test/src/ forge-std/=lib/forge-std/src/ solmate/=lib/solmate/src/ weird-erc20/=lib/weird-erc20/src/

These remappings mean:

  • To import from forge-std we would write: import "forge-std/Contract.sol";
  • To import from ds-test we would write: import "ds-test/Contract.sol";
  • To import from solmate we would write: import "solmate/Contract.sol";
  • To import from weird-erc20 we would write: import "weird-erc20/Contract.sol";

You can customize these remappings by creating a remappings.txt file in the root of your project.

Let's create a remapping called solmate-utils that points to the utils folder in the solmate repository!

solmate-utils/=lib/solmate/src/utils/

Now we can import any of the contracts in src/utils of the solmate repository like so:

import "solmate-utils/Contract.sol";

Updating dependencies

You can update a specific dependency to the latest commit on the version you have specified using forge update <dep>. For example, if we wanted to pull the latest commit from our previously installed master-version of solmate, we would run:

$ forge update lib/solmate

Alternatively, you can do this for all dependencies at once by just running forge update.

Removing dependencies

You can remove dependencies using forge remove <deps>..., where <deps> is either the full path to the dependency or just the name. For example, to remove solmate both of these commands are equivalent:

$ forge remove solmate # ... is equivalent to ... $ forge remove lib/solmate

Hardhat compatibility

Forge also supports Hardhat-style projects where dependencies are npm packages (stored in node_modules) and contracts are stored in contracts as opposed to src.

To enable Hardhat compatibility mode pass the --hh flag.