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Basic Example Pallet

The Example: A simple example of a FRAME pallet demonstrating concepts, APIs and structures common to most FRAME runtimes.

Run cargo doc --package pallet-example-basic --open to view this pallet’s documentation.

This pallet serves as an example and is not meant to be used in production.

Documentation Guidelines:

  • Documentation comments (i.e. /// comment) - should accompany pallet functions and be restricted to the pallet interface, not the internals of the pallet implementation. Only state inputs, outputs, and a brief description that mentions whether calling it requires root, but without repeating the source code details. Capitalize the first word of each documentation comment and end it with a full stop. See Generic example of annotating source code with documentation comments
  • Self-documenting code - Try to refactor code to be self-documenting.
  • Code comments - Supplement complex code with a brief explanation, not every line of code.
  • Identifiers - surround by backticks (i.e. INHERENT_IDENTIFIER, InherentType, u64)
  • Usage scenarios - should be simple doctests. The compiler should ensure they stay valid.
  • Extended tutorials - should be moved to external files and refer to.
  • Mandatory - include all of the sections/subsections where MUST is specified.
  • Optional - optionally include sections/subsections where CAN is specified.

Documentation Template:

Copy and paste this template from frame/examples/basic/src/lib.rs into file frame/<INSERT_CUSTOM_PALLET_NAME>/src/lib.rs of your own custom pallet and complete it.

// Add heading with custom pallet name


// Add simple description

// Include the following links that shows what trait needs to be implemented to use the pallet // and the supported dispatchables that are documented in the Call enum.

  • [Config]
  • [Call]
  • [Pallet]

## Overview

// Short description of pallet’s purpose. // Links to Traits that should be implemented. // What this pallet is for. // What functionality the pallet provides. // When to use the pallet (use case examples). // How it is used. // Inputs it uses and the source of each input. // Outputs it produces.

## Terminology

// Add terminology used in the custom pallet. Include concepts, storage items, or actions that you think // deserve to be noted to give context to the rest of the documentation or pallet usage. The author needs to // use some judgment about what is included. We don’t want a list of every storage item nor types - the user // can go to the code for that. For example, “transfer fee” is obvious and should not be included, but // “free balance” and “reserved balance” should be noted to give context to the pallet. // Please do not link to outside resources. The reference docs should be the ultimate source of truth.

## Goals

// Add goals that the custom pallet is designed to achieve.

### Scenarios


// Describe requirements prior to interacting with the custom pallet. // Describe the process of interacting with the custom pallet for this scenario and public API functions used.

## Interface

### Supported Origins

// What origins are used and supported in this pallet (root, signed, none) // i.e. root when `ensure_root` used // i.e. none when `ensure_none` used // i.e. signed when `ensure_signed` used


### Types

// Type aliases. Include any associated types and where the user would typically define them.


// Reference documentation of aspects such as storageItems and dispatchable functions should // only be included in the https://docs.rs Rustdocs for Substrate and not repeated in the // README file.

### Dispatchable Functions

// A brief description of dispatchable functions and a link to the rustdoc with their actual documentation.

// MUST have link to Call enum // MUST have origin information included in function doc // CAN have more info up to the user

### Public Functions

// A link to the rustdoc and any notes about usage in the pallet, not for specific functions. // For example, in the Balances Pallet: “Note that when using the publicly exposed functions, // you (the runtime developer) are responsible for implementing any necessary checks // (e.g. that the sender is the signer) before calling a function that will affect storage.”

// It is up to the writer of the respective pallet (with respect to how much information to provide).

#### Public Inspection functions - Immutable (getters)

// Insert a subheading for each getter function signature

##### `example_getter_name()`

// What it returns // Why, when, and how often to call it // When it could panic or error // When safety issues to consider

#### Public Mutable functions (changing state)

// Insert a subheading for each setter function signature

##### `example_setter_name(origin, parameter_name: T::ExampleType)`

// What state it changes // Why, when, and how often to call it // When it could panic or error // When safety issues to consider // What parameter values are valid and why

### Storage Items

// Explain any storage items included in this pallet

### Digest Items

// Explain any digest items included in this pallet

### Inherent Data

// Explain what inherent data (if any) is defined in the pallet and any other related types

### Events:

// Insert events for this pallet if any

### Errors:

// Explain what generates errors

## Usage

// Insert 2-3 examples of usage and code snippets that show how to // use <INSERT_CUSTOM_PALLET_NAME> Pallet in a custom pallet.

### Prerequisites

// Show how to include necessary imports for <INSERT_CUSTOM_PALLET_NAME> and derive // your pallet configuration trait with the INSERT_CUSTOM_PALLET_NAME trait.


pub trait Config: <INSERT_CUSTOM_PALLET_NAME>::Config { } ```

### Simple Code Snippet

// Show a simple example (e.g. how to query a public getter function of <INSERT_CUSTOM_PALLET_NAME>)

### Example from FRAME

// Show a usage example in an actual runtime

// See: // - Substrate TCR https://github.com/parity-samples/substrate-tcr // - Substrate Kitties https://shawntabrizi.github.io/substrate-collectables-workshop/#/

## Genesis Config

## Dependencies

// Dependencies on other FRAME pallets and the genesis config should be mentioned, // but not the Rust Standard Library. // Genesis configuration modifications that may be made to incorporate this pallet // Interaction with other pallets

## Related Pallets

// Interaction with other pallets in the form of a bullet point list

## References

// Links to reference material, if applicable. For example, Phragmen, W3F research, etc. // that the implementation is based on.



  • The pallet module in each FRAME pallet hosts the most important items needed to construct this pallet.
  • Autogenerated weights for pallet_example_basic


  • A simple signed extension that checks for the set_dummy call. In that case, it increases the priority and prints some log.