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Creating a Balances Pallet

As mentioned earlier, at the heart of a blockchain is a state machine.

We can create a very naive state machine using simple Rust abstractions, and through this help learn about Rust in the context of blockchains.

We want keep our code organized, so we will not really start building in the main.rs file, but actually in separate Rust modules. We can think of the main.rs file as glue which brings everything together, and we will see that over the course of this workshop.

"Pallet" is a term specific to the Polkadot SDK, which refers to Rust modules which contain logic specific for your blockchain runtime. We are going to start using this term here because what we build here will closely mirror what you will see with the Polkadot SDK.

Balances

Pretty much every blockchain has logic handles the balances of users on that blockchain.

This Pallet will tell you: how much balance each user has, provide functions which allow users to transfer those balances, and even some low level functions to allow your blockchain system to manipulate those balances if needed. Think for example if you want to mint new tokens which don't already exist.

This is a great starting point, and the very first Pallet we will build.

Creating a Struct

  1. Create a new file in your src folder named balances.rs

    touch src/balances.rs

  2. In this file, create a struct, which will act as the state and entry point for this module:

    pub struct Pallet {}

  3. Now go back to src/main.rs, and import this new module, which will include all the logic inside of it:

    mod balances;

  4. If we run your program now, you will see it still compiles and runs, but might show you some warnings like:

    warning: struct `Pallet` is never constructed
    --> src/balances.rs:1:12
    |
    1 | pub struct Pallet {    }
    |              ^^^^^^
    |
    = note: `#[warn(dead_code)]` on by default
    

    warning: `pr` (bin "pr") generated 1 warning

    That's fine! We haven't started using our Pallet yet, but you can see that the Rust compiler is detecting our new code, and bringing that logic into our main program. This is the start of building our first state machine module.

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Creating a Balances Pallet

As mentioned earlier, at the heart of a blockchain is a state machine.

We can create a very naive state machine using simple Rust abstractions, and through this help learn about Rust in the context of blockchains.

We want keep our code organized, so we will not really start building in the main.rs file, but actually in separate Rust modules. We can think of the main.rs file as glue which brings everything together, and we will see that over the course of this workshop.

"Pallet" is a term specific to the Polkadot SDK, which refers to Rust modules which contain logic specific for your blockchain runtime. We are going to start using this term here because what we build here will closely mirror what you will see with the Polkadot SDK.

Balances

Pretty much every blockchain has logic handles the balances of users on that blockchain.

This Pallet will tell you: how much balance each user has, provide functions which allow users to transfer those balances, and even some low level functions to allow your blockchain system to manipulate those balances if needed. Think for example if you want to mint new tokens which don't already exist.

This is a great starting point, and the very first Pallet we will build.

Creating a Struct

  1. Create a new file in your src folder named balances.rs

    touch src/balances.rs

  2. In this file, create a struct, which will act as the state and entry point for this module:

    pub struct Pallet {}

  3. Now go back to src/main.rs, and import this new module, which will include all the logic inside of it:

    mod balances;

  4. If we run your program now, you will see it still compiles and runs, but might show you some warnings like:

    warning: struct `Pallet` is never constructed
    --> src/balances.rs:1:12
    |
    1 | pub struct Pallet {    }
    |              ^^^^^^
    |
    = note: `#[warn(dead_code)]` on by default
    

    warning: `pr` (bin "pr") generated 1 warning

    That's fine! We haven't started using our Pallet yet, but you can see that the Rust compiler is detecting our new code, and bringing that logic into our main program. This is the start of building our first state machine module.

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