add general OnDust implemention (#328)

Author: wangjj9219

currencies/Cargo.toml

@@ -23,7 +23,7 @@ orml-utilities = { path = "../utilities", version = "0.3.3-dev", default-feature
 [dev-dependencies]
 sp-core = { version = "2.0.0", default-features = false }
 pallet-balances = "2.0.0"
-tokens = { package = "orml-tokens", path = "../tokens" }
+orml_tokens = { package = "orml-tokens", path = "../tokens", version = "0.3.3-dev" }
 
 clear_on_drop = { version = "0.2.4", features = ["no_cc"] }	# https://github.com/paritytech/substrate/issues/4179
 

currencies/src/mock.rs

@@ -3,7 +3,7 @@
 #![cfg(test)]
 
 use frame_support::{impl_outer_event, impl_outer_origin, parameter_types};
-use orml_traits::{parameter_type_with_key, OnDust};
+use orml_traits::parameter_type_with_key;
 use pallet_balances;
 use sp_core::H256;
 use sp_runtime::{
@@ -12,8 +12,6 @@ use sp_runtime::{
 	AccountId32, ModuleId, Perbill,
 };
 
-use tokens;
-
 use super::*;
 
 mod currencies {
@@ -24,7 +22,7 @@ impl_outer_event! {
 	pub enum TestEvent for Runtime {
 		frame_system<T>,
 		currencies<T>,
-		tokens<T>,
+		orml_tokens<T>,
 		pallet_balances<T>,
 	}
 }
@@ -91,13 +89,6 @@ impl pallet_balances::Trait for Runtime {
 }
 pub type PalletBalances = pallet_balances::Module<Runtime>;
 
-pub struct MockOnDust;
-impl OnDust<AccountId, CurrencyId, Balance> for MockOnDust {
-	fn on_dust(who: &AccountId, currency_id: CurrencyId, amount: Balance) {
-		let _ = <Tokens as MultiCurrency<_>>::transfer(currency_id, who, &DustAccount::get(), amount);
-	}
-}
-
 parameter_type_with_key! {
 	pub ExistentialDeposits: |currency_id: CurrencyId| -> Balance {
 		Default::default()
@@ -108,16 +99,16 @@ parameter_types! {
 	pub DustAccount: AccountId = ModuleId(*b"orml/dst").into_account();
 }
 
-impl tokens::Trait for Runtime {
+impl orml_tokens::Trait for Runtime {
 	type Event = TestEvent;
 	type Balance = Balance;
 	type Amount = i64;
 	type CurrencyId = CurrencyId;
 	type WeightInfo = ();
 	type ExistentialDeposits = ExistentialDeposits;
-	type OnDust = MockOnDust;
+	type OnDust = orml_tokens::TransferDust<Runtime, DustAccount>;
 }
-pub type Tokens = tokens::Module<Runtime>;
+pub type Tokens = orml_tokens::Module<Runtime>;
 
 pub const NATIVE_CURRENCY_ID: CurrencyId = 1;
 pub const X_TOKEN_ID: CurrencyId = 2;
@@ -186,7 +177,7 @@ impl ExtBuilder {
 		.assimilate_storage(&mut t)
 		.unwrap();
 
-		tokens::GenesisConfig::<Runtime> {
+		orml_tokens::GenesisConfig::<Runtime> {
 			endowed_accounts: self
 				.endowed_accounts
 				.into_iter()

tokens/src/lib.rs

@@ -85,6 +85,28 @@ pub trait WeightInfo {
 	fn transfer_all() -> Weight;
 }
 
+pub struct TransferDust<T, GetAccountId>(marker::PhantomData<(T, GetAccountId)>);
+impl<T, GetAccountId> OnDust<T::AccountId, T::CurrencyId, T::Balance> for TransferDust<T, GetAccountId>
+where
+	T: Trait,
+	GetAccountId: Get<T::AccountId>,
+{
+	fn on_dust(who: &T::AccountId, currency_id: T::CurrencyId, amount: T::Balance) {
+		// transfer the dust to treasury account, ignore the result,
+		// if failed will leave some dust which still could be recycled.
+		let _ = <Module<T> as MultiCurrency<T::AccountId>>::transfer(currency_id, who, &GetAccountId::get(), amount);
+	}
+}
+
+pub struct BurnDust<T>(marker::PhantomData<T>);
+impl<T: Trait> OnDust<T::AccountId, T::CurrencyId, T::Balance> for BurnDust<T> {
+	fn on_dust(who: &T::AccountId, currency_id: T::CurrencyId, amount: T::Balance) {
+		// burn the dust, ignore the result,
+		// if failed will leave some dust which still could be recycled.
+		let _ = Module::<T>::withdraw(currency_id, who, amount);
+	}
+}
+
 pub trait Trait: frame_system::Trait {
 	type Event: From<Event<Self>> + Into<<Self as frame_system::Trait>::Event>;
 

tokens/src/mock.rs

@@ -270,13 +270,6 @@ impl pallet_elections_phragmen::Trait for Runtime {
 	type WeightInfo = ();
 }
 
-pub struct MockOnDust;
-impl OnDust<AccountId, CurrencyId, Balance> for MockOnDust {
-	fn on_dust(who: &AccountId, currency_id: CurrencyId, amount: Balance) {
-		let _ = <Tokens as MultiCurrency<_>>::transfer(currency_id, who, &DustAccount::get(), amount);
-	}
-}
-
 parameter_type_with_key! {
 	pub ExistentialDeposits: |currency_id: CurrencyId| -> Balance {
 		match currency_id {
@@ -298,7 +291,7 @@ impl Trait for Runtime {
 	type CurrencyId = CurrencyId;
 	type WeightInfo = ();
 	type ExistentialDeposits = ExistentialDeposits;
-	type OnDust = MockOnDust;
+	type OnDust = TransferDust<Runtime, DustAccount>;
 }
 pub type Tokens = Module<Runtime>;
 pub type TreasuryCurrencyAdapter = <Runtime as pallet_treasury::Trait>::Currency;