How to import a local library into another local library in sway?

fuel · September 6, 2023, 7:01am

How to import a local library into another local library in sway?

opened 07:00AM - 06 Sep 23 UTC

closed 09:20AM - 07 Sep 23 UTC

# Local Library Imports in Sway: A Challenge Hello there! We're grappling wit…h a rather intricate issue concerning local library imports within Sway. Let's delve into this problem. ## The Scenario Imagine you have a contract consisting of three files: `structs.sw`, `events.sw`, and `main.sw`. I need to import a struct defined in `structs.sw` into `events.sw`. It sounds simple, but there's more to it than meets the eye. ### The Contract's Components #### `structs.sw` This library, `structs.sw`, holds the `struct Counter` and its associated `default()` implementation. The `struct Counter` is used in the storage of `main.sw`. https://github.com/PaulZhemanov/fuel-counter-contract/blob/library-import-issue/counter-contract/src/structs.sw #### `events.sw` Now, `events.sw` is where the action is. It houses the `struct IncrementEvent` , which is vital for the indexer, and requires the `struct Counter` . https://github.com/PaulZhemanov/fuel-counter-contract/blob/library-import-issue/counter-contract/src/events.sw #### `main.sw` In our main file, `main.sw`, we import both `events.sw` and `structs.sw` libraries. But our usage of `Counter` in the storage is where things get interesting. https://github.com/PaulZhemanov/fuel-counter-contract/blob/library-import-issue/counter-contract/src/main.sw#L1-L12 Additionally, within the `fn increment()`, there's an event named `IncrementEvent`. https://github.com/PaulZhemanov/fuel-counter-contract/blob/library-import-issue/counter-contract/src/main.sw#L28-L38 ## The Challenge Here's where it gets tricky. We need to import `struct Counter`, which is defined in the `structs.sw` library, into the `events.sw` library. But when we run `forc build`, it throws this error: ``` >>> forc build Compiling library core (/Users/alexey/.forc/git/checkouts/std-9be0d6062747ea7/04a597093e7441898933dd412b8e4dc6ac860cd3/sway-lib-core) Compiling library std (git+https://github.com/fuellabs/sway?tag=v0.44.1#04a597093e7441898933dd412b8e4dc6ac860cd3) Compiling contract counter-contract (/Users/alexey/Desktop/fuel-counter-contract/counter-contract) error --> /Users/alexey/Desktop/fuel-counter-contract/counter-contract/src/main.sw:1:5 | 0 | contract; 1 | mod events; | ^^^^^^ Module "events::structs" could not be found. 2 | mod structs; 3 | use events::*; | ____ error --> /Users/alexey/Desktop/fuel-counter-contract/counter-contract/src/events.sw:6:14 | 4 | 5 | pub struct IncrementEvent{ 6 | counter: Counter | ^^^^^^^ Could not find symbol "Counter" in this scope. 7 | } | ____ error --> /Users/alexey/Desktop/fuel-counter-contract/counter-contract/src/events.sw:6:14 | 4 | 5 | pub struct IncrementEvent{ 6 | counter: Counter | ^^^^^^^ Unknown type name "Counter". 7 | } | ____ Aborting due to 3 errors. Error: Failed to compile counter-contract ``` ## Toolchain ``` Default host: aarch64-apple-darwin fuelup home: /Users/alexey/.fuelup installed toolchains -------------------- beta-3-aarch64-apple-darwin beta-4-rc.2-aarch64-apple-darwin latest-aarch64-apple-darwin (default) hotfix my-custom-toolchain active toolchain ----------------- latest-aarch64-apple-darwin (default) forc : 0.44.1 - forc-client - forc-deploy : 0.44.1 - forc-run : 0.44.1 - forc-doc : 0.44.1 - forc-explore : 0.28.1 - forc-fmt : 0.44.1 - forc-index : 0.20.7 - forc-lsp : 0.44.1 - forc-tx : 0.44.1 - forc-wallet : 0.3.0 fuel-core : 0.20.4 fuel-core-keygen : Error getting version string fuel-indexer : 0.20.7 fuels versions --------------- forc : 0.45 forc-wallet : 0.45 ``` ### How to reproduce ``` fuelup self update fuelup install latest fuelup default latest git clone https://github.com/PaulZhemanov/fuel-counter-contract.git cd fuel-counter-contract. git checkout library-import-issue cd counter-contract forc build ```

The solution is to change use structs::Counter; to use ::structs::Counter; in events.sw.

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How to import a local library into another local library in sway?

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