fix some discrepancies in generic-asset (#4221)

* fix generic-asset

* Update lib.rs

* Update lib.rs

* Update lib.rs

* Update lib.rs

substrate/frame/generic-asset/src/lib.rs

@@ -95,9 +95,10 @@
 //! This will emit the `Transferred` event.
 //! - `reserve`: Moves an amount from free balance to reserved balance.
 //! - `unreserve`: Move up to an amount from reserved balance to free balance. This function cannot fail.
+//! - `mint_free`: Mint to an account's free balance.
+//! - `burn_free`: Burn an account's free balance.
 //! - `slash`: Deduct up to an amount from the combined balance of `who`, preferring to deduct from the
 //!	free balance. This function cannot fail.
-//! - `reward`: Add up to an amount to the free balance of an account.
 //! - `slash_reserved`: Deduct up to an amount from reserved balance of an account. This function cannot fail.
 //! - `repatriate_reserved`: Move up to an amount from reserved balance of an account to free balance of another
 //! account.
@@ -109,7 +110,7 @@
 //!
 //! The following examples show how to use the Generic Asset module in your custom module.
 //!
-//! ### Examples from the PRML
+//! ### Examples from the frame module
 //!
 //! The Fees module uses the `Currency` trait to handle fee charge/refund, and its types inherit from `Currency`:
 //!
@@ -162,7 +163,7 @@ use sp_runtime::traits::{
 use sp_std::prelude::*;
 use sp_std::{cmp, result, fmt::Debug};
 use frame_support::{
-	decl_event, decl_module, decl_storage, ensure, dispatch, decl_error,
+	decl_event, decl_module, decl_storage, ensure, decl_error,
 	traits::{
 		Currency, ExistenceRequirement, Imbalance, LockIdentifier, LockableCurrency, ReservableCurrency,
 		SignedImbalance, UpdateBalanceOutcome, WithdrawReason, WithdrawReasons, TryDrop,
@@ -359,7 +360,7 @@ decl_module! {
 		fn deposit_event() = default;
 
 		/// Create a new kind of asset.
-		fn create(origin, options: AssetOptions<T::Balance, T::AccountId>) -> dispatch::DispatchResult {
+		fn create(origin, options: AssetOptions<T::Balance, T::AccountId>) -> DispatchResult {
 			let origin = ensure_signed(origin)?;
 			let id = Self::next_asset_id();
 
@@ -392,7 +393,7 @@ decl_module! {
 			origin,
 			#[compact] asset_id: T::AssetId,
 			new_permission: PermissionLatest<T::AccountId>
-		) -> dispatch::DispatchResult {
+		) -> DispatchResult {
 			let origin = ensure_signed(origin)?;
 
 			let permissions: PermissionVersions<T::AccountId> = new_permission.into();
@@ -410,56 +411,20 @@ decl_module! {
 
 		/// Mints an asset, increases its total issuance.
 		/// The origin must have `mint` permissions.
-		fn mint(origin, #[compact] asset_id: T::AssetId, to: T::AccountId, amount: T::Balance)
-			-> dispatch::DispatchResult
-		{
-			let origin = ensure_signed(origin)?;
-			if Self::check_permission(&asset_id, &origin, &PermissionType::Mint) {
-				let original_free_balance = Self::free_balance(&asset_id, &to);
-				let current_total_issuance = <TotalIssuance<T>>::get(asset_id);
-				let new_total_issuance = current_total_issuance.checked_add(&amount)
-					.ok_or(Error::<T>::TotalMintingOverflow)?;
-				let value = original_free_balance.checked_add(&amount)
-					.ok_or(Error::<T>::FreeMintingOverflow)?;
-
-				<TotalIssuance<T>>::insert(asset_id, new_total_issuance);
-				Self::set_free_balance(&asset_id, &to, value);
-
-				Self::deposit_event(RawEvent::Minted(asset_id, to, amount));
-
-				Ok(())
-			} else {
-				Err(Error::<T>::NoMintPermission)?
-			}
+		fn mint(origin, #[compact] asset_id: T::AssetId, to: T::AccountId, amount: T::Balance) -> DispatchResult {
+			let who = ensure_signed(origin)?;
+			Self::mint_free(&asset_id, &who, &to, &amount)?;
+			Self::deposit_event(RawEvent::Minted(asset_id, to, amount));
+			Ok(())
 		}
 
 		/// Burns an asset, decreases its total issuance.
-		///
 		/// The `origin` must have `burn` permissions.
-		fn burn(origin, #[compact] asset_id: T::AssetId, to: T::AccountId, amount: T::Balance)
-			-> dispatch::DispatchResult
-		{
-			let origin = ensure_signed(origin)?;
-
-			if Self::check_permission(&asset_id, &origin, &PermissionType::Burn) {
-				let original_free_balance = Self::free_balance(&asset_id, &to);
-
-				let current_total_issuance = <TotalIssuance<T>>::get(asset_id);
-				let new_total_issuance = current_total_issuance.checked_sub(&amount)
-					.ok_or(Error::<T>::TotalBurningUnderflow)?;
-				let value = original_free_balance.checked_sub(&amount)
-					.ok_or(Error::<T>::FreeBurningUnderflow)?;
-
-				<TotalIssuance<T>>::insert(asset_id, new_total_issuance);
-
-				Self::set_free_balance(&asset_id, &to, value);
-
-				Self::deposit_event(RawEvent::Burned(asset_id, to, amount));
-
-				Ok(())
-			} else {
-				Err(Error::<T>::NoBurnPermission)?
-			}
+		fn burn(origin, #[compact] asset_id: T::AssetId, to: T::AccountId, amount: T::Balance) -> DispatchResult {
+			let who = ensure_signed(origin)?;
+			Self::burn_free(&asset_id, &who, &to, &amount)?;
+			Self::deposit_event(RawEvent::Burned(asset_id, to, amount));
+			Ok(())
 		}
 
 		/// Can be used to create reserved tokens.
@@ -468,7 +433,7 @@ decl_module! {
 			origin,
 			asset_id: T::AssetId,
 			options: AssetOptions<T::Balance, T::AccountId>
-		) -> dispatch::DispatchResult {
+		) -> DispatchResult {
 			ensure_root(origin)?;
 			Self::create_asset(Some(asset_id), None, options)
 		}
@@ -565,6 +530,53 @@ impl<T: Trait> Module<T> {
 		<ReservedBalance<T>>::get(asset_id, who)
 	}
 
+	/// Mint to an account's free balance, without event
+	pub fn mint_free(
+		asset_id: &T::AssetId,
+		who: &T::AccountId,
+		to: &T::AccountId,
+		amount: &T::Balance,
+	) -> DispatchResult {
+		if Self::check_permission(asset_id, who, &PermissionType::Mint) {
+			let original_free_balance = Self::free_balance(&asset_id, &to);
+			let current_total_issuance = <TotalIssuance<T>>::get(asset_id);
+			let new_total_issuance = current_total_issuance.checked_add(&amount)
+				.ok_or(Error::<T>::TotalMintingOverflow)?;
+			let value = original_free_balance.checked_add(&amount)
+				.ok_or(Error::<T>::FreeMintingOverflow)?;
+
+			<TotalIssuance<T>>::insert(asset_id, new_total_issuance);
+			Self::set_free_balance(&asset_id, &to, value);
+			Ok(())
+		} else {
+			Err(Error::<T>::NoMintPermission)?
+		}
+	}
+
+	/// Burn an account's free balance, without event
+	pub fn burn_free(
+		asset_id: &T::AssetId,
+		who: &T::AccountId,
+		to: &T::AccountId,
+		amount: &T::Balance,
+	) -> DispatchResult {
+		if Self::check_permission(asset_id, who, &PermissionType::Burn) {
+			let original_free_balance = Self::free_balance(asset_id, to);
+
+			let current_total_issuance = <TotalIssuance<T>>::get(asset_id);
+			let new_total_issuance = current_total_issuance.checked_sub(amount)
+				.ok_or(Error::<T>::TotalBurningUnderflow)?;
+			let value = original_free_balance.checked_sub(amount)
+				.ok_or(Error::<T>::FreeBurningUnderflow)?;
+
+			<TotalIssuance<T>>::insert(asset_id, new_total_issuance);
+			Self::set_free_balance(asset_id, to, value);
+			Ok(())
+		} else {
+			Err(Error::<T>::NoBurnPermission)?
+		}
+	}
+
 	/// Creates an asset.
 	///
 	/// # Arguments
@@ -577,7 +589,7 @@ impl<T: Trait> Module<T> {
 		asset_id: Option<T::AssetId>,
 		from_account: Option<T::AccountId>,
 		options: AssetOptions<T::Balance, T::AccountId>,
-	) -> dispatch::DispatchResult {
+	) -> DispatchResult {
 		let asset_id = if let Some(asset_id) = asset_id {
 			ensure!(!<TotalIssuance<T>>::exists(&asset_id), Error::<T>::IdAlreadyTaken);
 			ensure!(asset_id < Self::next_asset_id(), Error::<T>::IdUnavailable);
@@ -610,7 +622,7 @@ impl<T: Trait> Module<T> {
 		from: &T::AccountId,
 		to: &T::AccountId,
 		amount: T::Balance
-	) -> dispatch::DispatchResult {
+	) -> DispatchResult {
 		let new_balance = Self::free_balance(asset_id, from)
 			.checked_sub(&amount)
 			.ok_or(Error::<T>::InsufficientBalance)?;
@@ -631,7 +643,7 @@ impl<T: Trait> Module<T> {
 		from: &T::AccountId,
 		to: &T::AccountId,
 		amount: T::Balance,
-	) -> dispatch::DispatchResult {
+	) -> DispatchResult {
 		Self::make_transfer(asset_id, from, to, amount)?;
 
 		if from != to {
@@ -646,7 +658,7 @@ impl<T: Trait> Module<T> {
 	/// If the free balance is lower than `amount`, then no funds will be moved and an `Err` will
 	/// be returned. This is different behavior than `unreserve`.
 	pub fn reserve(asset_id: &T::AssetId, who: &T::AccountId, amount: T::Balance)
-		-> dispatch::DispatchResult
+		-> DispatchResult
 	{
 		// Do we need to consider that this is an atomic transaction?
 		let original_reserve_balance = Self::reserved_balance(asset_id, who);
@@ -683,7 +695,7 @@ impl<T: Trait> Module<T> {
 	/// then `Some(remaining)` will be returned. Full completion is given by `None`.
 	/// NOTE: LOW-LEVEL: This will not attempt to maintain total issuance. It is expected that
 	/// the caller will do this.
-	fn slash(asset_id: &T::AssetId, who: &T::AccountId, amount: T::Balance) -> Option<T::Balance> {
+	pub fn slash(asset_id: &T::AssetId, who: &T::AccountId, amount: T::Balance) -> Option<T::Balance> {
 		let free_balance = Self::free_balance(asset_id, who);
 		let free_slash = sp_std::cmp::min(free_balance, amount);
 		let new_free_balance = free_balance - free_slash;
@@ -701,7 +713,7 @@ impl<T: Trait> Module<T> {
 	/// is less than `amount`, then a non-zero second item will be returned.
 	/// NOTE: LOW-LEVEL: This will not attempt to maintain total issuance. It is expected that
 	/// the caller will do this.
-	fn slash_reserved(asset_id: &T::AssetId, who: &T::AccountId, amount: T::Balance) -> Option<T::Balance> {
+	pub fn slash_reserved(asset_id: &T::AssetId, who: &T::AccountId, amount: T::Balance) -> Option<T::Balance> {
 		let original_reserve_balance = Self::reserved_balance(asset_id, who);
 		let slash = sp_std::cmp::min(original_reserve_balance, amount);
 		let new_reserve_balance = original_reserve_balance - slash;
@@ -720,7 +732,7 @@ impl<T: Trait> Module<T> {
 	/// the `remaining` would be returned, else `Zero::zero()`.
 	/// NOTE: LOW-LEVEL: This will not attempt to maintain total issuance. It is expected that
 	/// the caller will do this.
-	fn repatriate_reserved(
+	pub fn repatriate_reserved(
 		asset_id: &T::AssetId,
 		who: &T::AccountId,
 		beneficiary: &T::AccountId,
@@ -785,7 +797,7 @@ impl<T: Trait> Module<T> {
 		_amount: T::Balance,
 		reasons: WithdrawReasons,
 		new_balance: T::Balance,
-	) -> dispatch::DispatchResult {
+	) -> DispatchResult {
 		if asset_id != &Self::staking_asset_id() {
 			return Ok(());
 		}