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API Reference

Complete reference for all ERC721S functions and parameters.

State Variables​

VariableTypeDescription
pricePerSeconduint256Cost per second of subscription in wei
minSubscriptionDurationuint256Minimum purchasable subscription period in seconds
maxSubscriptionDurationuint256Maximum purchasable subscription period in seconds
fundsRecipientaddressAddress that receives subscription payments

User Functions​

subscribe​

Creates a new subscription or extends an existing one.

function subscribe(uint256 duration) external payable

Parameters:

  • duration - Subscription duration in seconds

Requirements:

  • duration must be between minSubscriptionDuration and maxSubscriptionDuration
  • msg.value must equal getSubscriptionCost(duration)

Behavior:

  • If the caller has no token, mints one with ID derived from their address
  • If subscription is expired, sets new expiration to block.timestamp + duration
  • If subscription is active, extends expiration by duration

View Functions​

getSubscriptionCost​

Calculates the cost for a given subscription duration.

function getSubscriptionCost(uint256 duration) public view returns (uint256)

Parameters:

  • duration - Subscription duration in seconds

Returns:

  • Cost in wei

deriveTokenId​

Computes the token ID for a given address.

function deriveTokenId(address user) public pure returns (uint256)

Parameters:

  • user - User address

Returns:

  • Token ID (derived from address)

hasActiveSubscription​

Checks if an address has an active subscription.

function hasActiveSubscription(address user) public view returns (bool)

Parameters:

  • user - User address to check

Returns:

  • true if the user has an active (non-expired) subscription

isSubscriptionActive​

Checks if a specific token has an active subscription.

function isSubscriptionActive(uint256 tokenId) public view returns (bool)

Parameters:

  • tokenId - Token ID to check

Returns:

  • true if the subscription is not expired

Owner Functions​

setPrice​

Updates the price per second for subscriptions.

function setPrice(uint256 newPricePerSecond) external onlyOwner

Parameters:

  • newPricePerSecond - New price in wei per second

setFundsRecipient​

Updates the address that receives subscription payments.

function setFundsRecipient(address newRecipient) external onlyOwner

Parameters:

  • newRecipient - New recipient address

withdraw​

Withdraws all ETH from the contract to the funds recipient.

function withdraw() external onlyOwner

Events​

Subscribed​

Emitted when a user subscribes or extends their subscription.

event Subscribed(address indexed user, uint256 indexed tokenId, uint256 expiration)

Security Considerations​

  • The contract uses OpenZeppelin's ReentrancyGuard to prevent reentrancy attacks during payment handling
  • Ownership transfers use Ownable2Step requiring explicit acceptance to prevent accidental transfers
  • Token transfers are disabled (non-transferable tokens)