Module sui::transfer_policy

Defines the TransferPolicy type and the logic to approve TransferRequests.

• TransferPolicy - is a highly customizable primitive, which provides an interface for the type owner to set custom transfer rules for every deal performed in the Kiosk or a similar system that integrates with TP.

• Once a TransferPolicy<T> is created for and shared (or frozen), the type T becomes tradable in Kiosks. On every purchase operation, a TransferRequest is created and needs to be confirmed by the TransferPolicy hot potato or transaction will fail.

• Type owner (creator) can set any Rules as long as the ecosystem supports them. All of the Rules need to be resolved within a single transaction (eg pay royalty and pay fixed commission). Once required actions are performed, the TransferRequest can be "confirmed" via confirm_request call.

• TransferPolicy aims to be the main interface for creators to control trades of their types and collect profits if a fee is required on sales. Custom policies can be removed at any moment, and the change will affect all instances of the type at once.

• Struct TransferRequest

• Struct TransferPolicy

• Struct TransferPolicyCap

• Struct TransferPolicyCreated

• Struct TransferPolicyDestroyed

• Struct RuleKey

• Constants

• Function new_request

• Function new

• Function default

• Function withdraw

• Function destroy_and_withdraw

• Function confirm_request

• Function add_rule

• Function get_rule

• Function add_to_balance

• Function add_receipt

• Function has_rule

• Function remove_rule

• Function uid

• Function uid_mut_as_owner

• Function rules

• Function item

• Function paid

• Function from

use std::address;
use std::ascii;
use std::bcs;
use std::option;
use std::string;
use std::type_name;
use std::vector;
use sui::accumulator;
use sui::address;
use sui::bag;
use sui::balance;
use sui::coin;
use sui::config;
use sui::deny_list;
use sui::dynamic_field;
use sui::dynamic_object_field;
use sui::event;
use sui::hex;
use sui::object;
use sui::package;
use sui::party;
use sui::sui;
use sui::table;
use sui::transfer;
use sui::tx_context;
use sui::types;
use sui::url;
use sui::vec_map;
use sui::vec_set;

Struct `TransferRequest`

A "Hot Potato" forcing the buyer to get a transfer permission from the item type (T) owner on purchase attempt.

public struct TransferRequest<phantom T>

Fields

item: sui::object::ID

The ID of the transferred item. Although the T has no constraints, the main use case for this module is to work with Objects.

paid: u64

Amount of SUI paid for the item. Can be used to calculate the fee / transfer policy enforcement.

from: sui::object::ID

The ID of the Kiosk / Safe the object is being sold from. Can be used by the TransferPolicy implementors.

receipts: sui::vec_set::VecSet<std::type_name::TypeName>

Collected Receipts. Used to verify that all of the rules were followed and TransferRequest can be confirmed.

Struct `TransferPolicy`

A unique capability that allows the owner of the T to authorize transfers. Can only be created with the Publisher object. Although there's no limitation to how many policies can be created, for most of the cases there's no need to create more than one since any of the policies can be used to confirm the TransferRequest.

public struct TransferPolicy<phantom T> has key, store

Fields

id: sui::object::UID

balance: sui::balance::Balance<sui::sui::SUI>

The Balance of the TransferPolicy which collects SUI. By default, transfer policy does not collect anything , and it's a matter of an implementation of a specific rule - whether to add to balance and how much.

rules: sui::vec_set::VecSet<std::type_name::TypeName>

Set of types of attached rules - used to verify receipts when a TransferRequest is received in confirm_request function. Additionally provides a way to look up currently attached Rules.

Struct `TransferPolicyCap`

A Capability granting the owner permission to add/remove rules as well as to withdraw and destroy_and_withdraw the TransferPolicy.

public struct TransferPolicyCap<phantom T> has key, store

Fields

id: sui::object::UID

policy_id: sui::object::ID

Struct `TransferPolicyCreated`

Event that is emitted when a publisher creates a new TransferPolicyCap making the discoverability and tracking the supported types easier.

public struct TransferPolicyCreated<phantom T> has copy, drop

Fields

id: sui::object::ID

Struct `TransferPolicyDestroyed`

Event that is emitted when a publisher destroys a TransferPolicyCap. Allows for tracking supported policies.

public struct TransferPolicyDestroyed<phantom T> has copy, drop

Fields

id: sui::object::ID

Struct `RuleKey`

Key to store "Rule" configuration for a specific TransferPolicy.

public struct RuleKey<phantom T: drop> has copy, drop, store

Fields

Constants

The number of receipts does not match the TransferPolicy requirement.

const EPolicyNotSatisfied: u64 = 0;

A completed rule is not set in the TransferPolicy.

const EIllegalRule: u64 = 1;

A Rule is not set.

const EUnknownRequirement: u64 = 2;

Attempting to create a Rule that is already set.

const ERuleAlreadySet: u64 = 3;

Trying to withdraw or close_and_withdraw with a wrong Cap.

const ENotOwner: u64 = 4;

Trying to withdraw more than there is.

const ENotEnough: u64 = 5;

Function `new_request`

Construct a new TransferRequest hot potato which requires an approving action from the creator to be destroyed / resolved. Once created, it must be confirmed in the confirm_request call otherwise the transaction will fail.

public fun new_request<T>(item: sui::object::ID, paid: u64, from: sui::object::ID): sui::transfer_policy::TransferRequest<T>

Implementation

public fun new_request<T>(item: ID, paid: u64, from: ID): TransferRequest<T> {
    TransferRequest { item, paid, from, receipts: vec_set::empty() }
}

Function `new`

Register a type in the Kiosk system and receive a TransferPolicy and a TransferPolicyCap for the type. The TransferPolicy is required to confirm kiosk deals for the T. If there's no TransferPolicy available for use, the type can not be traded in kiosks.

public fun new<T>(pub: &sui::package::Publisher, ctx: &mut sui::tx_context::TxContext): (sui::transfer_policy::TransferPolicy<T>, sui::transfer_policy::TransferPolicyCap<T>)

Implementation

public fun new<T>(pub: &Publisher, ctx: &mut TxContext): (TransferPolicy<T>, TransferPolicyCap<T>) {
    assert!(package::from_package<T>(pub), 0);
    let id = object::new(ctx);
    let policy_id = id.to_inner();
    event::emit(TransferPolicyCreated<T> { id: policy_id });
    (
        TransferPolicy { id, rules: vec_set::empty(), balance: balance::zero() },
        TransferPolicyCap { id: object::new(ctx), policy_id },
    )
}

Function `default`

Initialize the Transfer Policy in the default scenario: Create and share the TransferPolicy, transfer TransferPolicyCap to the transaction sender.

entry fun default<T>(pub: &sui::package::Publisher, ctx: &mut sui::tx_context::TxContext)

Implementation

entry fun default<T>(pub: &Publisher, ctx: &mut TxContext) {
    let (policy, cap) = new<T>(pub, ctx);
    sui::transfer::share_object(policy);
    sui::transfer::transfer(cap, ctx.sender());
}

Function `withdraw`

Withdraw some amount of profits from the TransferPolicy. If amount is not specified, all profits are withdrawn.

public fun withdraw<T>(self: &mut sui::transfer_policy::TransferPolicy<T>, cap: &sui::transfer_policy::TransferPolicyCap<T>, amount: std::option::Option<u64>, ctx: &mut sui::tx_context::TxContext): sui::coin::Coin<sui::sui::SUI>

Implementation

public fun withdraw<T>(
    self: &mut TransferPolicy<T>,
    cap: &TransferPolicyCap<T>,
    amount: Option<u64>,
    ctx: &mut TxContext,
): Coin<SUI> {
    assert!(object::id(self) == cap.policy_id, ENotOwner);
    let amount = if (amount.is_some()) {
        let amt = amount.destroy_some();
        assert!(amt <= self.balance.value(), ENotEnough);
        amt
    } else {
        self.balance.value()
    };
    coin::take(&mut self.balance, amount, ctx)
}

Function `destroy_and_withdraw`

Destroy a TransferPolicyCap. Can be performed by any party as long as they own it.

public fun destroy_and_withdraw<T>(self: sui::transfer_policy::TransferPolicy<T>, cap: sui::transfer_policy::TransferPolicyCap<T>, ctx: &mut sui::tx_context::TxContext): sui::coin::Coin<sui::sui::SUI>

Implementation

public fun destroy_and_withdraw<T>(
    self: TransferPolicy<T>,
    cap: TransferPolicyCap<T>,
    ctx: &mut TxContext,
): Coin<SUI> {
    assert!(object::id(&self) == cap.policy_id, ENotOwner);
    let TransferPolicyCap { id: cap_id, policy_id } = cap;
    let TransferPolicy { id, rules: _, balance } = self;
    id.delete();
    cap_id.delete();
    event::emit(TransferPolicyDestroyed<T> { id: policy_id });
    balance.into_coin(ctx)
}

Function `confirm_request`

Allow a TransferRequest for the type T. The call is protected by the type constraint, as only the publisher of the T can get TransferPolicy<T>.

Note: unless there's a policy for T to allow transfers, Kiosk trades will not be possible.

public fun confirm_request<T>(self: &sui::transfer_policy::TransferPolicy<T>, request: sui::transfer_policy::TransferRequest<T>): (sui::object::ID, u64, sui::object::ID)

Implementation

public fun confirm_request<T>(
    self: &TransferPolicy<T>,
    request: TransferRequest<T>,
): (ID, u64, ID) {
    let TransferRequest { item, paid, from, receipts } = request;
    let mut completed = receipts.into_keys();
    let mut total = completed.length();
    assert!(total == self.rules.length(), EPolicyNotSatisfied);
    while (total > 0) {
        let rule_type = completed.pop_back();
        assert!(self.rules.contains(&rule_type), EIllegalRule);
        total = total - 1;
    };
    (item, paid, from)
}

Function `add_rule`

Add a custom Rule to the TransferPolicy. Once set, TransferRequest must receive a confirmation of the rule executed so the hot potato can be unpacked.

• T: the type to which TransferPolicy is applied.
• Rule: the witness type for the Custom rule
• Config: a custom configuration for the rule

Config requires drop to allow creators to remove any policy at any moment, even if graceful unpacking has not been implemented in a "rule module".

public fun add_rule<T, Rule: drop, Config: drop, store>(_: Rule, policy: &mut sui::transfer_policy::TransferPolicy<T>, cap: &sui::transfer_policy::TransferPolicyCap<T>, cfg: Config)

Implementation

public fun add_rule<T, Rule: drop, Config: store + drop>(
    _: Rule,
    policy: &mut TransferPolicy<T>,
    cap: &TransferPolicyCap<T>,
    cfg: Config,
) {
    assert!(object::id(policy) == cap.policy_id, ENotOwner);
    assert!(!has_rule<T, Rule>(policy), ERuleAlreadySet);
    df::add(&mut policy.id, RuleKey<Rule> {}, cfg);
    policy.rules.insert(type_name::with_defining_ids<Rule>())
}

Function `get_rule`

Get the custom Config for the Rule (can be only one per "Rule" type).

public fun get_rule<T, Rule: drop, Config: drop, store>(_: Rule, policy: &sui::transfer_policy::TransferPolicy<T>): &Config

Implementation

public fun get_rule<T, Rule: drop, Config: store + drop>(
    _: Rule,
    policy: &TransferPolicy<T>,
): &Config {
    df::borrow(&policy.id, RuleKey<Rule> {})
}

Function `add_to_balance`

Add some SUI to the balance of a TransferPolicy.

public fun add_to_balance<T, Rule: drop>(_: Rule, policy: &mut sui::transfer_policy::TransferPolicy<T>, coin: sui::coin::Coin<sui::sui::SUI>)

Implementation

public fun add_to_balance<T, Rule: drop>(_: Rule, policy: &mut TransferPolicy<T>, coin: Coin<SUI>) {
    assert!(has_rule<T, Rule>(policy), EUnknownRequirement);
    coin::put(&mut policy.balance, coin)
}

Function `add_receipt`

Adds a Receipt to the TransferRequest, unblocking the request and confirming that the policy requirements are satisfied.

public fun add_receipt<T, Rule: drop>(_: Rule, request: &mut sui::transfer_policy::TransferRequest<T>)

Implementation

public fun add_receipt<T, Rule: drop>(_: Rule, request: &mut TransferRequest<T>) {
    request.receipts.insert(type_name::with_defining_ids<Rule>())
}

Function `has_rule`

Check whether a custom rule has been added to the TransferPolicy.

public fun has_rule<T, Rule: drop>(policy: &sui::transfer_policy::TransferPolicy<T>): bool

Implementation

public fun has_rule<T, Rule: drop>(policy: &TransferPolicy<T>): bool {
    df::exists_(&policy.id, RuleKey<Rule> {})
}

Function `remove_rule`

Remove the Rule from the TransferPolicy.

public fun remove_rule<T, Rule: drop, Config: drop, store>(policy: &mut sui::transfer_policy::TransferPolicy<T>, cap: &sui::transfer_policy::TransferPolicyCap<T>)

Implementation

public fun remove_rule<T, Rule: drop, Config: store + drop>(
    policy: &mut TransferPolicy<T>,
    cap: &TransferPolicyCap<T>,
) {
    assert!(object::id(policy) == cap.policy_id, ENotOwner);
    let _: Config = df::remove(&mut policy.id, RuleKey<Rule> {});
    policy.rules.remove(&type_name::with_defining_ids<Rule>());
}

Function `uid`

Allows reading custom attachments to the TransferPolicy if there are any.

public fun uid<T>(self: &sui::transfer_policy::TransferPolicy<T>): &sui::object::UID

Implementation

public fun uid<T>(self: &TransferPolicy<T>): &UID { &self.id }

Function `uid_mut_as_owner`

Get a mutable reference to the self.id to enable custom attachments to the TransferPolicy.

public fun uid_mut_as_owner<T>(self: &mut sui::transfer_policy::TransferPolicy<T>, cap: &sui::transfer_policy::TransferPolicyCap<T>): &mut sui::object::UID

Implementation

public fun uid_mut_as_owner<T>(self: &mut TransferPolicy<T>, cap: &TransferPolicyCap<T>): &mut UID {
    assert!(object::id(self) == cap.policy_id, ENotOwner);
    &mut self.id
}

Function `rules`

Read the rules field from the TransferPolicy.

public fun rules<T>(self: &sui::transfer_policy::TransferPolicy<T>): &sui::vec_set::VecSet<std::type_name::TypeName>

Implementation

public fun rules<T>(self: &TransferPolicy<T>): &VecSet<TypeName> {
    &self.rules
}

Function `item`

Get the item field of the TransferRequest.

public fun item<T>(self: &sui::transfer_policy::TransferRequest<T>): sui::object::ID

Implementation

public fun item<T>(self: &TransferRequest<T>): ID { self.item }

Function `paid`

Get the paid field of the TransferRequest.

public fun paid<T>(self: &sui::transfer_policy::TransferRequest<T>): u64

Implementation

public fun paid<T>(self: &TransferRequest<T>): u64 { self.paid }

Function `from`

Get the from field of the TransferRequest.

public fun from<T>(self: &sui::transfer_policy::TransferRequest<T>): sui::object::ID

Implementation

public fun from<T>(self: &TransferRequest<T>): ID { self.from }