Example.SmartContract.NEP17

Neo N3 NEP-17 Token Smart Contract Example

Overview

This example demonstrates how to implement a compliant NEP-17 token on the Neo N3 blockchain. NEP-17 is the fungible token standard for Neo N3, similar to ERC-20 on Ethereum. This sample provides a complete implementation with essential token functionality and administrative features.

Key Features

• Complete NEP-17 standard implementation
• Owner and minter role management
• Token minting and burning capabilities
• Contract update functionality
• Event notifications for state changes

Technical Implementation

The SampleNep17Token contract demonstrates several key aspects of NEP-17 token design:

NEP-17 Standard Compliance

• Implements all required NEP-17 methods and properties
• Inherits from the base Nep17Token class
• Includes proper event notifications
• Declares standard compliance with [SupportedStandards] attribute

Role-Based Access Control

The contract implements two distinct administrative roles:

1. Owner Role:

   • Controls contract ownership
   • Can update the contract
   • Can transfer ownership

2. Minter Role:

   • Controls token creation rights
   • Can mint new tokens
   • Can be assigned by the owner

Token Properties

• Symbol: "SampleNep17Token"
• Decimals: 8 (allowing for fractional tokens)
• Storage-based tracking of token balances and supply

Administrative Functions

• SetOwner: Transfers contract ownership to a new address
• SetMinter: Assigns minting rights to a new address
• Mint: Creates new tokens and assigns them to a specified address
• Burn: Destroys tokens from a specified address
• Update: Upgrades the contract to a new implementation

Events

The contract emits the following events:

• Transfer: When tokens are transferred between addresses
• SetOwner: When contract ownership changes
• SetMinter: When minting rights are reassigned

Security Considerations

• Permission checks using Runtime.CheckWitness
• Role-based authorization for sensitive operations
• Protected mint and burn operations
• Secured contract update mechanism

Usage Scenarios

This NEP-17 token implementation can be customized for:

• Fungible tokens and cryptocurrencies
• Governance tokens with voting rights
• Staking and reward systems
• Tokenized assets and securities
• In-application currencies

Customization Guide

To adapt this example for your own token:

1. Modify the token properties (Symbol, Decimals)
2. Update the initial owner and minter addresses
3. Adjust minting and burning logic as needed
4. Add any additional token-specific functionality
5. Configure permissions and access controls

Deployment and Interaction

Once deployed, the token can be:

• Minted by the assigned minter
• Transferred between users
• Burned when no longer needed
• Managed by the contract owner
• Updated to new implementations

This example serves as a solid foundation for creating compliant, secure, and functional fungible tokens on the Neo N3 blockchain.