Basic Contract

Each contract should be in its own crate. In a folder, create two files:

• Cargo.toml: The manifest.
• lib.rs: The default library file.

Inside the Cargo.toml you will need to specify parameters in the [package], [dependencies], [lib] type, and [features] sections:

[package]
name = "my_contract"
version = "0.1.0"
authors = ["Your Name <name@email.com>"]
edition = "2021"

[dependencies]
ink = { version = "4.3", default-features = false}
ink_metadata = { version = "4.3", features = ["derive"], optional = true }

scale = { package = "parity-scale-codec", version = "3", default-features = false, features = ["derive"] }
scale-info = { version = "2.5", default-features = false, features = ["derive"], optional = true }

[dev-dependencies]
ink_e2e = { version = "4.3" }

[lib]
path = "lib.rs"

[features]
default = ["std"]
std = [
    "ink/std",
    "scale/std",
    "scale-info/std"
]
ink-as-dependency = []
e2e-tests = []

In the library file - ink! has a few minimum requirements:

• #![cfg_attr(not(feature = "std"), no_std, no_main)] at the beginning of each contract file.
• a module with #[ink::contract].
• a (storage) struct - that can be empty - with #[ink(storage)].
• at least one constructor with #[ink(constructor)].
• at least one fn with #[ink(message)].

In the lib.rs the minimum implementation is:

#![cfg_attr(not(feature = "std"), no_std)]

#[ink::contract]
mod my_contract {

    #[ink(storage)]
    pub struct MyContract {}

    impl MyContract {
        #[ink(constructor)]
        pub fn new() -> Self {
            Self {}
        }

        #[ink(message)]
        pub fn do_something(&self) {
            ()
        }
    }
}

The flipper smart contract is the most basic example provided by ink! team.

Using Swanky

You can also use Swanky Suite to fast track your development efforts when setting up the project. Go to this section to learn how to bootstrap a smart contract using Swanky