FeverTokens Packages

🔍 Overview

The FeverTokens Package-Oriented Framework is a composable smart contract architecture based on the EIP-2535 Diamond Standard. It provides a structured and modular approach for building scalable, upgradable, and reusable smart contract packages tailored to institutional and mission-critical systems.

By following a strict separation of concerns, this framework makes smart contracts:

• Easier to audit and maintain

• Highly composable and upgradable

• Compatible with tooling for version management and deployment

• Ready for integration into larger smart contract systems using the FeverTokens Hub

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💎 Diamond Architecture Principles

Each package is a modular facet of a Diamond and adheres to the following design principles:

• Separation of Concerns: Interfaces, logic, and storage are explicitly decoupled.

• Interface Definitions: Cleanly specified internal and external interfaces for integration and documentation.

• Storage Management: Explicit and namespaced layout management using custom storage slots.

• Upgradeable Logic: Built to support safe upgrades via the Diamond proxy architecture.

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📦 Package Structure

Each package must include five distinct components, each as a separate file:

File	Purpose
IMyPackageInternal.sol	Internal interface: declares events, structs, enums
IMyPackage.sol	External interface: defines externally callable functions
MyPackageStorage.sol	Storage layout using diamond storage pattern
MyPackageInternal.sol	Internal logic: uses and modifies package storage
MyPackagePackage.sol	External-facing contract: wraps internal logic

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🔹 Internal Interface – IMyPackageInternal.sol

Defines the internal elements of the package: enums, structs, events, and errors.

interface IMyPackageInternal {
  enum MyEnum {
    Option1,
    Option2
  }

  struct MyStruct1 {
    uint256 value;
    address addr;
  }

  struct MyStruct2 {
    bool active;
    uint256 count;
  }

  event MyEvent1(address indexed sender, uint256 value);
  event MyEvent2(address indexed actor, bool action);
}

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🔹 External Interface – IMyPackage.sol

Inherits the internal interface and exposes external functions.

import './IMyPackageInternal.sol';

interface IMyPackage is IMyPackageInternal {
  function myFunction1(uint256 value1) external;
  function myFunction2(address addr, uint256 value2) external;
}

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🔹 Storage Layout – MyPackageStorage.sol

Encapsulates the state in a Layout struct, using a dedicated slot for namespacing based on ERC-7201.

import './IMyPackageInternal.sol';

library MyPackageStorage {
  struct Layout {
    uint256 value1;
    address addr1;
    uint256 value2;
    MyStruct1 myObject1;
    bool active;
  }

  bytes32 constant STORAGE_SLOT =
    keccak256(abi.encode(uint256(keccak256('company.storage.MyPackage')) - 1)) &
      ~bytes32(uint256(0xff));

  function layout() internal pure returns (Layout storage l) {
    bytes32 slot = STORAGE_SLOT;
    assembly {
      l.slot := slot
    }
  }
}

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🔹 Internal Logic – MyPackageInternal.sol

Implements the core business logic using the namespaced storage.

import './IMyPackageInternal.sol';
import { MyPackageStorage } from './MyPackageStorage.sol';

abstract contract MyPackageInternal is IMyPackageInternal {
  using MyPackageStorage for MyPackageStorage.Layout;

  function _myFunction1(uint256 value1) internal {
    MyPackageStorage.Layout storage l = MyPackageStorage.layout();
    // Logic using l.value1
  }

  function _myFunction2(address addr, uint256 value2) internal {
    MyPackageStorage.Layout storage l = MyPackageStorage.layout();
    // Logic using l.addr1 and l.value2
  }
}

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🔹 Package Entry Point – MyPackage.sol

Implements external interface and delegates to internal logic.

import {IMyPackage} from "./IMyPackage.sol";
import {MyPackageInternal} from "./MyPackageInternal.sol";

contract MyPackagePackage is IMyPackage, MyPackageInternal {
    function myFunction1(uint256 value1_) external override {
    _myFunction1(value1_);
    }

    function myFunction2(address addr_, uint256 value2_) external override {
        _myFunction2(addr_, value2_);
    }

}

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✅ Best Practices

• Function naming: Prefix internal functions with _ (e.g., _myFunction1) for clarity.

• External function implementation: Avoid direct calls to internal functions; always use the _ prefixed versions. Use override to ensure compliance with the interface.

• Parameter naming: Use trailing underscores (e.g., value1_) to avoid variable shadowing.

• Testing: Unit-test each package and integration-test multiple packages as part of a system.

• Documentation: Comment the purpose and logic of each package, especially for critical functions.

• Storage safety: Never change the order or type of variables in a layout struct once deployed.

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🚀 Create Your Own Package (Quick Guide)

1. Define internal elements in IMyPackageInternal.sol:

   • Enums, structs, events

2. Define external interface in IMyPackage.sol:

   • Extend the internal interface

   • Declare externally accessible functions

3. Create a storage layout in MyPackageStorage.sol:

   • Add a namespaced Layout struct

   • Declare the storage slot using keccak256

4. Implement internal logic in MyPackageInternal.sol:

   • Use the layout via MyPackageStorage.layout()

   • Implement internal helper methods

5. Build your package in MyPackagePackage.sol:

   • Inherit from IMyPackage and MyPackageInternal

   • Implement external methods by calling internal functions

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📚 License

Open-source under the Apache License 2.0. You are free to use, modify, and integrate in compliance with the license.