Make pallet Assets instantiable (#8483)

* Make pallet Assets instantiable

* use instantiable benchmarks

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

substrate/frame/assets/src/benchmarking.rs

@@ -24,7 +24,7 @@ use super::*;
 use sp_runtime::traits::Bounded;
 use frame_system::RawOrigin as SystemOrigin;
 use frame_benchmarking::{
-	benchmarks, account, whitelisted_caller, whitelist_account, impl_benchmark_test_suite
+	benchmarks_instance_pallet, account, whitelisted_caller, whitelist_account, impl_benchmark_test_suite
 };
 use frame_support::traits::Get;
 use frame_support::{traits::EnsureOrigin, dispatch::UnfilteredDispatchable};
@@ -33,13 +33,13 @@ use crate::Pallet as Assets;
 
 const SEED: u32 = 0;
 
-fn create_default_asset<T: Config>(is_sufficient: bool)
+fn create_default_asset<T: Config<I>, I: 'static>(is_sufficient: bool)
 	-> (T::AccountId, <T::Lookup as StaticLookup>::Source)
 {
 	let caller: T::AccountId = whitelisted_caller();
 	let caller_lookup = T::Lookup::unlookup(caller.clone());
 	let root = SystemOrigin::Root.into();
-	assert!(Assets::<T>::force_create(
+	assert!(Assets::<T, I>::force_create(
 		root,
 		Default::default(),
 		caller_lookup.clone(),
@@ -49,14 +49,14 @@ fn create_default_asset<T: Config>(is_sufficient: bool)
 	(caller, caller_lookup)
 }
 
-fn create_default_minted_asset<T: Config>(is_sufficient: bool, amount: T::Balance)
+fn create_default_minted_asset<T: Config<I>, I: 'static>(is_sufficient: bool, amount: T::Balance)
 	-> (T::AccountId, <T::Lookup as StaticLookup>::Source)
 {
-	let (caller, caller_lookup)  = create_default_asset::<T>(is_sufficient);
+	let (caller, caller_lookup)  = create_default_asset::<T, I>(is_sufficient);
 	if !is_sufficient {
 		T::Currency::make_free_balance_be(&caller, T::Currency::minimum_balance());
 	}
-	assert!(Assets::<T>::mint(
+	assert!(Assets::<T, I>::mint(
 		SystemOrigin::Signed(caller.clone()).into(),
 		Default::default(),
 		caller_lookup.clone(),
@@ -65,42 +65,42 @@ fn create_default_minted_asset<T: Config>(is_sufficient: bool, amount: T::Balanc
 	(caller, caller_lookup)
 }
 
-fn swap_is_sufficient<T: Config>(s: &mut bool) {
-	Asset::<T>::mutate(&T::AssetId::default(), |maybe_a|
+fn swap_is_sufficient<T: Config<I>, I: 'static>(s: &mut bool) {
+	Asset::<T, I>::mutate(&T::AssetId::default(), |maybe_a|
 		if let Some(ref mut a) = maybe_a { sp_std::mem::swap(s, &mut a.is_sufficient) }
 	);
 }
 
-fn add_consumers<T: Config>(minter: T::AccountId, n: u32) {
+fn add_consumers<T: Config<I>, I: 'static>(minter: T::AccountId, n: u32) {
 	let origin = SystemOrigin::Signed(minter);
 	let mut s = false;
-	swap_is_sufficient::<T>(&mut s);
+	swap_is_sufficient::<T, I>(&mut s);
 	for i in 0..n {
 		let target = account("consumer", i, SEED);
 		T::Currency::make_free_balance_be(&target, T::Currency::minimum_balance());
 		let target_lookup = T::Lookup::unlookup(target);
-		assert!(Assets::<T>::mint(origin.clone().into(), Default::default(), target_lookup, 100u32.into()).is_ok());
+		assert!(Assets::<T, I>::mint(origin.clone().into(), Default::default(), target_lookup, 100u32.into()).is_ok());
 	}
-	swap_is_sufficient::<T>(&mut s);
+	swap_is_sufficient::<T, I>(&mut s);
 }
 
-fn add_sufficients<T: Config>(minter: T::AccountId, n: u32) {
+fn add_sufficients<T: Config<I>, I: 'static>(minter: T::AccountId, n: u32) {
 	let origin = SystemOrigin::Signed(minter);
 	let mut s = true;
-	swap_is_sufficient::<T>(&mut s);
+	swap_is_sufficient::<T, I>(&mut s);
 	for i in 0..n {
 		let target = account("sufficient", i, SEED);
 		let target_lookup = T::Lookup::unlookup(target);
-		assert!(Assets::<T>::mint(origin.clone().into(), Default::default(), target_lookup, 100u32.into()).is_ok());
+		assert!(Assets::<T, I>::mint(origin.clone().into(), Default::default(), target_lookup, 100u32.into()).is_ok());
 	}
-	swap_is_sufficient::<T>(&mut s);
+	swap_is_sufficient::<T, I>(&mut s);
 }
 
-fn add_approvals<T: Config>(minter: T::AccountId, n: u32) {
+fn add_approvals<T: Config<I>, I: 'static>(minter: T::AccountId, n: u32) {
 	T::Currency::deposit_creating(&minter, T::ApprovalDeposit::get() * n.into());
 	let minter_lookup = T::Lookup::unlookup(minter.clone());
 	let origin = SystemOrigin::Signed(minter);
-	Assets::<T>::mint(
+	Assets::<T, I>::mint(
 		origin.clone().into(),
 		Default::default(),
 		minter_lookup,
@@ -110,7 +110,7 @@ fn add_approvals<T: Config>(minter: T::AccountId, n: u32) {
 		let target = account("approval", i, SEED);
 		T::Currency::make_free_balance_be(&target, T::Currency::minimum_balance());
 		let target_lookup = T::Lookup::unlookup(target);
-		Assets::<T>::approve_transfer(
+		Assets::<T, I>::approve_transfer(
 			origin.clone().into(),
 			Default::default(),
 			target_lookup,
@@ -119,7 +119,7 @@ fn add_approvals<T: Config>(minter: T::AccountId, n: u32) {
 	}
 }
 
-fn assert_last_event<T: Config>(generic_event: <T as Config>::Event) {
+fn assert_last_event<T: Config<I>, I: 'static>(generic_event: <T as Config<I>>::Event) {
 	let events = frame_system::Pallet::<T>::events();
 	let system_event: <T as frame_system::Config>::Event = generic_event.into();
 	// compare to the last event record
@@ -127,7 +127,7 @@ fn assert_last_event<T: Config>(generic_event: <T as Config>::Event) {
 	assert_eq!(event, &system_event);
 }
 
-fn assert_event<T: Config>(generic_event: <T as Config>::Event) {
+fn assert_event<T: Config<I>, I: 'static>(generic_event: <T as Config<I>>::Event) {
 	let system_event: <T as frame_system::Config>::Event = generic_event.into();
 	let events = frame_system::Pallet::<T>::events();
 	assert!(events.iter().any(|event_record| {
@@ -135,14 +135,14 @@ fn assert_event<T: Config>(generic_event: <T as Config>::Event) {
 	}));
 }
 
-benchmarks! {
+benchmarks_instance_pallet! {
 	create {
 		let caller: T::AccountId = whitelisted_caller();
 		let caller_lookup = T::Lookup::unlookup(caller.clone());
-		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T>::max_value());
+		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T, I>::max_value());
 	}: _(SystemOrigin::Signed(caller.clone()), Default::default(), caller_lookup, 1u32.into())
 	verify {
-		assert_last_event::<T>(Event::Created(Default::default(), caller.clone(), caller).into());
+		assert_last_event::<T, I>(Event::Created(Default::default(), caller.clone(), caller).into());
 	}
 
 	force_create {
@@ -150,127 +150,127 @@ benchmarks! {
 		let caller_lookup = T::Lookup::unlookup(caller.clone());
 	}: _(SystemOrigin::Root, Default::default(), caller_lookup, true, 1u32.into())
 	verify {
-		assert_last_event::<T>(Event::ForceCreated(Default::default(), caller).into());
+		assert_last_event::<T, I>(Event::ForceCreated(Default::default(), caller).into());
 	}
 
 	destroy {
 		let c in 0 .. 5_000;
 		let s in 0 .. 5_000;
 		let a in 0 .. 5_00;
-		let (caller, _) = create_default_asset::<T>(true);
-		add_consumers::<T>(caller.clone(), c);
-		add_sufficients::<T>(caller.clone(), s);
-		add_approvals::<T>(caller.clone(), a);
-		let witness = Asset::<T>::get(T::AssetId::default()).unwrap().destroy_witness();
+		let (caller, _) = create_default_asset::<T, I>(true);
+		add_consumers::<T, I>(caller.clone(), c);
+		add_sufficients::<T, I>(caller.clone(), s);
+		add_approvals::<T, I>(caller.clone(), a);
+		let witness = Asset::<T, I>::get(T::AssetId::default()).unwrap().destroy_witness();
 	}: _(SystemOrigin::Signed(caller), Default::default(), witness)
 	verify {
-		assert_last_event::<T>(Event::Destroyed(Default::default()).into());
+		assert_last_event::<T, I>(Event::Destroyed(Default::default()).into());
 	}
 
 	mint {
-		let (caller, caller_lookup) = create_default_asset::<T>(true);
+		let (caller, caller_lookup) = create_default_asset::<T, I>(true);
 		let amount = T::Balance::from(100u32);
 	}: _(SystemOrigin::Signed(caller.clone()), Default::default(), caller_lookup, amount)
 	verify {
-		assert_last_event::<T>(Event::Issued(Default::default(), caller, amount).into());
+		assert_last_event::<T, I>(Event::Issued(Default::default(), caller, amount).into());
 	}
 
 	burn {
 		let amount = T::Balance::from(100u32);
-		let (caller, caller_lookup) = create_default_minted_asset::<T>(true, amount);
+		let (caller, caller_lookup) = create_default_minted_asset::<T, I>(true, amount);
 	}: _(SystemOrigin::Signed(caller.clone()), Default::default(), caller_lookup, amount)
 	verify {
-		assert_last_event::<T>(Event::Burned(Default::default(), caller, amount).into());
+		assert_last_event::<T, I>(Event::Burned(Default::default(), caller, amount).into());
 	}
 
 	transfer {
 		let amount = T::Balance::from(100u32);
-		let (caller, caller_lookup) = create_default_minted_asset::<T>(true, amount);
+		let (caller, caller_lookup) = create_default_minted_asset::<T, I>(true, amount);
 		let target: T::AccountId = account("target", 0, SEED);
 		let target_lookup = T::Lookup::unlookup(target.clone());
 	}: _(SystemOrigin::Signed(caller.clone()), Default::default(), target_lookup, amount)
 	verify {
-		assert_last_event::<T>(Event::Transferred(Default::default(), caller, target, amount).into());
+		assert_last_event::<T, I>(Event::Transferred(Default::default(), caller, target, amount).into());
 	}
 
 	transfer_keep_alive {
 		let mint_amount = T::Balance::from(200u32);
 		let amount = T::Balance::from(100u32);
-		let (caller, caller_lookup) = create_default_minted_asset::<T>(true, mint_amount);
+		let (caller, caller_lookup) = create_default_minted_asset::<T, I>(true, mint_amount);
 		let target: T::AccountId = account("target", 0, SEED);
 		let target_lookup = T::Lookup::unlookup(target.clone());
 	}: _(SystemOrigin::Signed(caller.clone()), Default::default(), target_lookup, amount)
 	verify {
 		assert!(frame_system::Pallet::<T>::account_exists(&caller));
-		assert_last_event::<T>(Event::Transferred(Default::default(), caller, target, amount).into());
+		assert_last_event::<T, I>(Event::Transferred(Default::default(), caller, target, amount).into());
 	}
 
 	force_transfer {
 		let amount = T::Balance::from(100u32);
-		let (caller, caller_lookup) = create_default_minted_asset::<T>(true, amount);
+		let (caller, caller_lookup) = create_default_minted_asset::<T, I>(true, amount);
 		let target: T::AccountId = account("target", 0, SEED);
 		let target_lookup = T::Lookup::unlookup(target.clone());
 	}: _(SystemOrigin::Signed(caller.clone()), Default::default(), caller_lookup, target_lookup, amount)
 	verify {
-		assert_last_event::<T>(
+		assert_last_event::<T, I>(
 			Event::Transferred(Default::default(), caller, target, amount).into()
 		);
 	}
 
 	freeze {
-		let (caller, caller_lookup) = create_default_minted_asset::<T>(true, 100u32.into());
+		let (caller, caller_lookup) = create_default_minted_asset::<T, I>(true, 100u32.into());
 	}: _(SystemOrigin::Signed(caller.clone()), Default::default(), caller_lookup)
 	verify {
-		assert_last_event::<T>(Event::Frozen(Default::default(), caller).into());
+		assert_last_event::<T, I>(Event::Frozen(Default::default(), caller).into());
 	}
 
 	thaw {
-		let (caller, caller_lookup) = create_default_minted_asset::<T>(true, 100u32.into());
-		Assets::<T>::freeze(
+		let (caller, caller_lookup) = create_default_minted_asset::<T, I>(true, 100u32.into());
+		Assets::<T, I>::freeze(
 			SystemOrigin::Signed(caller.clone()).into(),
 			Default::default(),
 			caller_lookup.clone(),
 		)?;
 	}: _(SystemOrigin::Signed(caller.clone()), Default::default(), caller_lookup)
 	verify {
-		assert_last_event::<T>(Event::Thawed(Default::default(), caller).into());
+		assert_last_event::<T, I>(Event::Thawed(Default::default(), caller).into());
 	}
 
 	freeze_asset {
-		let (caller, caller_lookup) = create_default_minted_asset::<T>(true, 100u32.into());
+		let (caller, caller_lookup) = create_default_minted_asset::<T, I>(true, 100u32.into());
 	}: _(SystemOrigin::Signed(caller.clone()), Default::default())
 	verify {
-		assert_last_event::<T>(Event::AssetFrozen(Default::default()).into());
+		assert_last_event::<T, I>(Event::AssetFrozen(Default::default()).into());
 	}
 
 	thaw_asset {
-		let (caller, caller_lookup) = create_default_minted_asset::<T>(true, 100u32.into());
-		Assets::<T>::freeze_asset(
+		let (caller, caller_lookup) = create_default_minted_asset::<T, I>(true, 100u32.into());
+		Assets::<T, I>::freeze_asset(
 			SystemOrigin::Signed(caller.clone()).into(),
 			Default::default(),
 		)?;
 	}: _(SystemOrigin::Signed(caller.clone()), Default::default())
 	verify {
-		assert_last_event::<T>(Event::AssetThawed(Default::default()).into());
+		assert_last_event::<T, I>(Event::AssetThawed(Default::default()).into());
 	}
 
 	transfer_ownership {
-		let (caller, _) = create_default_asset::<T>(true);
+		let (caller, _) = create_default_asset::<T, I>(true);
 		let target: T::AccountId = account("target", 0, SEED);
 		let target_lookup = T::Lookup::unlookup(target.clone());
 	}: _(SystemOrigin::Signed(caller), Default::default(), target_lookup)
 	verify {
-		assert_last_event::<T>(Event::OwnerChanged(Default::default(), target).into());
+		assert_last_event::<T, I>(Event::OwnerChanged(Default::default(), target).into());
 	}
 
 	set_team {
-		let (caller, _) = create_default_asset::<T>(true);
+		let (caller, _) = create_default_asset::<T, I>(true);
 		let target0 = T::Lookup::unlookup(account("target", 0, SEED));
 		let target1 = T::Lookup::unlookup(account("target", 1, SEED));
 		let target2 = T::Lookup::unlookup(account("target", 2, SEED));
 	}: _(SystemOrigin::Signed(caller), Default::default(), target0.clone(), target1.clone(), target2.clone())
 	verify {
-		assert_last_event::<T>(Event::TeamChanged(
+		assert_last_event::<T, I>(Event::TeamChanged(
 			Default::default(),
 			account("target", 0, SEED),
 			account("target", 1, SEED),
@@ -286,23 +286,23 @@ benchmarks! {
 		let symbol = vec![0u8; s as usize];
 		let decimals = 12;
 
-		let (caller, _) = create_default_asset::<T>(true);
-		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T>::max_value());
+		let (caller, _) = create_default_asset::<T, I>(true);
+		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T, I>::max_value());
 	}: _(SystemOrigin::Signed(caller), Default::default(), name.clone(), symbol.clone(), decimals)
 	verify {
 		let id = Default::default();
-		assert_last_event::<T>(Event::MetadataSet(id, name, symbol, decimals, false).into());
+		assert_last_event::<T, I>(Event::MetadataSet(id, name, symbol, decimals, false).into());
 	}
 
 	clear_metadata {
-		let (caller, _) = create_default_asset::<T>(true);
-		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T>::max_value());
+		let (caller, _) = create_default_asset::<T, I>(true);
+		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T, I>::max_value());
 		let dummy = vec![0u8; T::StringLimit::get() as usize];
 		let origin = SystemOrigin::Signed(caller.clone()).into();
-		Assets::<T>::set_metadata(origin, Default::default(), dummy.clone(), dummy, 12)?;
+		Assets::<T, I>::set_metadata(origin, Default::default(), dummy.clone(), dummy, 12)?;
 	}: _(SystemOrigin::Signed(caller), Default::default())
 	verify {
-		assert_last_event::<T>(Event::MetadataCleared(Default::default()).into());
+		assert_last_event::<T, I>(Event::MetadataCleared(Default::default()).into());
 	}
 
 	force_set_metadata {
@@ -313,10 +313,10 @@ benchmarks! {
 		let symbol = vec![0u8; s as usize];
 		let decimals = 12;
 
-		create_default_asset::<T>(true);
+		create_default_asset::<T, I>(true);
 
 		let origin = T::ForceOrigin::successful_origin();
-		let call = Call::<T>::force_set_metadata(
+		let call = Call::<T, I>::force_set_metadata(
 			Default::default(),
 			name.clone(),
 			symbol.clone(),
@@ -326,28 +326,28 @@ benchmarks! {
 	}: { call.dispatch_bypass_filter(origin)? }
 	verify {
 		let id = Default::default();
-		assert_last_event::<T>(Event::MetadataSet(id, name, symbol, decimals, false).into());
+		assert_last_event::<T, I>(Event::MetadataSet(id, name, symbol, decimals, false).into());
 	}
 
 	force_clear_metadata {
-		let (caller, _) = create_default_asset::<T>(true);
-		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T>::max_value());
+		let (caller, _) = create_default_asset::<T, I>(true);
+		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T, I>::max_value());
 		let dummy = vec![0u8; T::StringLimit::get() as usize];
 		let origin = SystemOrigin::Signed(caller.clone()).into();
-		Assets::<T>::set_metadata(origin, Default::default(), dummy.clone(), dummy, 12)?;
+		Assets::<T, I>::set_metadata(origin, Default::default(), dummy.clone(), dummy, 12)?;
 
 		let origin = T::ForceOrigin::successful_origin();
-		let call = Call::<T>::force_clear_metadata(Default::default());
+		let call = Call::<T, I>::force_clear_metadata(Default::default());
 	}: { call.dispatch_bypass_filter(origin)? }
 	verify {
-		assert_last_event::<T>(Event::MetadataCleared(Default::default()).into());
+		assert_last_event::<T, I>(Event::MetadataCleared(Default::default()).into());
 	}
 
 	force_asset_status {
-		let (caller, caller_lookup) = create_default_asset::<T>(true);
+		let (caller, caller_lookup) = create_default_asset::<T, I>(true);
 
 		let origin = T::ForceOrigin::successful_origin();
-		let call = Call::<T>::force_asset_status(
+		let call = Call::<T, I>::force_asset_status(
 			Default::default(),
 			caller_lookup.clone(),
 			caller_lookup.clone(),
@@ -359,12 +359,12 @@ benchmarks! {
 		);
 	}: { call.dispatch_bypass_filter(origin)? }
 	verify {
-		assert_last_event::<T>(Event::AssetStatusChanged(Default::default()).into());
+		assert_last_event::<T, I>(Event::AssetStatusChanged(Default::default()).into());
 	}
 
 	approve_transfer {
-		let (caller, _) = create_default_minted_asset::<T>(true, 100u32.into());
-		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T>::max_value());
+		let (caller, _) = create_default_minted_asset::<T, I>(true, 100u32.into());
+		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T, I>::max_value());
 
 		let id = Default::default();
 		let delegate: T::AccountId = account("delegate", 0, SEED);
@@ -372,12 +372,12 @@ benchmarks! {
 		let amount = 100u32.into();
 	}: _(SystemOrigin::Signed(caller.clone()), id, delegate_lookup, amount)
 	verify {
-		assert_last_event::<T>(Event::ApprovedTransfer(id, caller, delegate, amount).into());
+		assert_last_event::<T, I>(Event::ApprovedTransfer(id, caller, delegate, amount).into());
 	}
 
 	transfer_approved {
-		let (owner, owner_lookup) = create_default_minted_asset::<T>(true, 100u32.into());
-		T::Currency::make_free_balance_be(&owner, DepositBalanceOf::<T>::max_value());
+		let (owner, owner_lookup) = create_default_minted_asset::<T, I>(true, 100u32.into());
+		T::Currency::make_free_balance_be(&owner, DepositBalanceOf::<T, I>::max_value());
 
 		let id = Default::default();
 		let delegate: T::AccountId = account("delegate", 0, SEED);
@@ -385,44 +385,44 @@ benchmarks! {
 		let delegate_lookup = T::Lookup::unlookup(delegate.clone());
 		let amount = 100u32.into();
 		let origin = SystemOrigin::Signed(owner.clone()).into();
-		Assets::<T>::approve_transfer(origin, id, delegate_lookup.clone(), amount)?;
+		Assets::<T, I>::approve_transfer(origin, id, delegate_lookup.clone(), amount)?;
 
 		let dest: T::AccountId = account("dest", 0, SEED);
 		let dest_lookup = T::Lookup::unlookup(dest.clone());
 	}: _(SystemOrigin::Signed(delegate.clone()), id, owner_lookup, dest_lookup, amount)
 	verify {
 		assert!(T::Currency::reserved_balance(&owner).is_zero());
-		assert_event::<T>(Event::Transferred(id, owner, dest, amount).into());
+		assert_event::<T, I>(Event::Transferred(id, owner, dest, amount).into());
 	}
 
 	cancel_approval {
-		let (caller, _) = create_default_minted_asset::<T>(true, 100u32.into());
-		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T>::max_value());
+		let (caller, _) = create_default_minted_asset::<T, I>(true, 100u32.into());
+		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T, I>::max_value());
 
 		let id = Default::default();
 		let delegate: T::AccountId = account("delegate", 0, SEED);
 		let delegate_lookup = T::Lookup::unlookup(delegate.clone());
 		let amount = 100u32.into();
 		let origin = SystemOrigin::Signed(caller.clone()).into();
-		Assets::<T>::approve_transfer(origin, id, delegate_lookup.clone(), amount)?;
+		Assets::<T, I>::approve_transfer(origin, id, delegate_lookup.clone(), amount)?;
 	}: _(SystemOrigin::Signed(caller.clone()), id, delegate_lookup)
 	verify {
-		assert_last_event::<T>(Event::ApprovalCancelled(id, caller, delegate).into());
+		assert_last_event::<T, I>(Event::ApprovalCancelled(id, caller, delegate).into());
 	}
 
 	force_cancel_approval {
-		let (caller, caller_lookup) = create_default_minted_asset::<T>(true, 100u32.into());
-		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T>::max_value());
+		let (caller, caller_lookup) = create_default_minted_asset::<T, I>(true, 100u32.into());
+		T::Currency::make_free_balance_be(&caller, DepositBalanceOf::<T, I>::max_value());
 
 		let id = Default::default();
 		let delegate: T::AccountId = account("delegate", 0, SEED);
 		let delegate_lookup = T::Lookup::unlookup(delegate.clone());
 		let amount = 100u32.into();
 		let origin = SystemOrigin::Signed(caller.clone()).into();
-		Assets::<T>::approve_transfer(origin, id, delegate_lookup.clone(), amount)?;
+		Assets::<T, I>::approve_transfer(origin, id, delegate_lookup.clone(), amount)?;
 	}: _(SystemOrigin::Signed(caller.clone()), id, caller_lookup, delegate_lookup)
 	verify {
-		assert_last_event::<T>(Event::ApprovalCancelled(id, caller, delegate).into());
+		assert_last_event::<T, I>(Event::ApprovalCancelled(id, caller, delegate).into());
 	}
 }
 

substrate/frame/assets/src/extra_mutator.rs

@@ -25,20 +25,23 @@ use super::*;
 /// any uncommitted changes (see `commit` function) will be automatically committed to storage when
 /// dropped. Changes, even after committed, may be reverted to their original values with the
 /// `revert` function.
-pub struct ExtraMutator<T: Config> {
+pub struct ExtraMutator<T: Config<I>, I: 'static = ()> {
 	id: T::AssetId,
 	who: T::AccountId,
 	original: T::Extra,
 	pending: Option<T::Extra>,
 }
 
-impl<T: Config> Drop for ExtraMutator<T> {
+impl<T: Config<I>, I: 'static> Drop for ExtraMutator<T, I> {
 	fn drop(&mut self) {
-		debug_assert!(self.commit().is_ok(), "attempt to write to non-existent asset account");
+		debug_assert!(
+			self.commit().is_ok(),
+			"attempt to write to non-existent asset account"
+		);
 	}
 }
 
-impl<T: Config> sp_std::ops::Deref for ExtraMutator<T> {
+impl<T: Config<I>, I: 'static> sp_std::ops::Deref for ExtraMutator<T, I> {
 	type Target = T::Extra;
 	fn deref(&self) -> &T::Extra {
 		match self.pending {
@@ -48,7 +51,7 @@ impl<T: Config> sp_std::ops::Deref for ExtraMutator<T> {
 	}
 }
 
-impl<T: Config> sp_std::ops::DerefMut for ExtraMutator<T> {
+impl<T: Config<I>, I: 'static> sp_std::ops::DerefMut for ExtraMutator<T, I> {
 	fn deref_mut(&mut self) -> &mut T::Extra {
 		if self.pending.is_none() {
 			self.pending = Some(self.original.clone());
@@ -57,15 +60,16 @@ impl<T: Config> sp_std::ops::DerefMut for ExtraMutator<T> {
 	}
 }
 
-impl<T: Config> ExtraMutator<T> {
-	pub(super) fn maybe_new(id: T::AssetId, who: impl sp_std::borrow::Borrow<T::AccountId>)
-		-> Option<ExtraMutator<T>>
-	{
-		if Account::<T>::contains_key(id, who.borrow()) {
-			Some(ExtraMutator::<T> {
+impl<T: Config<I>, I: 'static> ExtraMutator<T, I> {
+	pub(super) fn maybe_new(
+		id: T::AssetId,
+		who: impl sp_std::borrow::Borrow<T::AccountId>,
+	) -> Option<ExtraMutator<T, I>> {
+		if Account::<T, I>::contains_key(id, who.borrow()) {
+			Some(ExtraMutator::<T, I> {
 				id,
 				who: who.borrow().clone(),
-				original: Account::<T>::get(id, who.borrow()).extra,
+				original: Account::<T, I>::get(id, who.borrow()).extra,
 				pending: None,
 			})
 		} else {
@@ -73,18 +77,17 @@ impl<T: Config> ExtraMutator<T> {
 		}
 	}
 
-
 	/// Commit any changes to storage.
 	pub fn commit(&mut self) -> Result<(), ()> {
 		if let Some(extra) = self.pending.take() {
-			Account::<T>::try_mutate_exists(self.id, self.who.borrow(), |maybe_account|
+			Account::<T, I>::try_mutate_exists(self.id, self.who.borrow(), |maybe_account| {
 				if let Some(ref mut account) = maybe_account {
 					account.extra = extra;
 					Ok(())
 				} else {
 					Err(())
 				}
-			)
+			})
 		} else {
 			Ok(())
 		}
@@ -93,13 +96,13 @@ impl<T: Config> ExtraMutator<T> {
 	/// Revert any changes, even those already committed by `self` and drop self.
 	pub fn revert(mut self) -> Result<(), ()> {
 		self.pending = None;
-		Account::<T>::try_mutate_exists(self.id, self.who.borrow(), |maybe_account|
+		Account::<T, I>::try_mutate_exists(self.id, self.who.borrow(), |maybe_account| {
 			if let Some(ref mut account) = maybe_account {
 				account.extra = self.original.clone();
 				Ok(())
 			} else {
 				Err(())
 			}
-		)
+		})
 	}
 }

substrate/frame/assets/src/functions.rs

@@ -20,37 +20,40 @@
 use super::*;
 
 // The main implementation block for the module.
-impl<T: Config> Pallet<T> {
+impl<T: Config<I>, I: 'static> Pallet<T, I> {
 	// Public immutables
 
 	/// Return the extra "sid-car" data for `id`/`who`, or `None` if the account doesn't exist.
-	pub fn adjust_extra(id: T::AssetId, who: impl sp_std::borrow::Borrow<T::AccountId>)
-		-> Option<ExtraMutator<T>>
-	{
+	pub fn adjust_extra(
+		id: T::AssetId,
+		who: impl sp_std::borrow::Borrow<T::AccountId>,
+	) -> Option<ExtraMutator<T, I>> {
 		ExtraMutator::maybe_new(id, who)
 	}
 
 	/// Get the asset `id` balance of `who`.
 	pub fn balance(id: T::AssetId, who: impl sp_std::borrow::Borrow<T::AccountId>) -> T::Balance {
-		Account::<T>::get(id, who.borrow()).balance
+		Account::<T, I>::get(id, who.borrow()).balance
 	}
 
 	/// Get the total supply of an asset `id`.
 	pub fn total_supply(id: T::AssetId) -> T::Balance {
-		Asset::<T>::get(id).map(|x| x.supply).unwrap_or_else(Zero::zero)
+		Asset::<T, I>::get(id)
+			.map(|x| x.supply)
+			.unwrap_or_else(Zero::zero)
 	}
 
 	pub(super) fn new_account(
 		who: &T::AccountId,
-		d: &mut AssetDetails<T::Balance, T::AccountId, DepositBalanceOf<T>>,
+		d: &mut AssetDetails<T::Balance, T::AccountId, DepositBalanceOf<T, I>>,
 	) -> Result<bool, DispatchError> {
-		let accounts = d.accounts.checked_add(1).ok_or(Error::<T>::Overflow)?;
+		let accounts = d.accounts.checked_add(1).ok_or(Error::<T, I>::Overflow)?;
 		let is_sufficient = if d.is_sufficient {
 			frame_system::Pallet::<T>::inc_sufficients(who);
 			d.sufficients += 1;
 			true
 		} else {
-			frame_system::Pallet::<T>::inc_consumers(who).map_err(|_| Error::<T>::NoProvider)?;
+			frame_system::Pallet::<T>::inc_consumers(who).map_err(|_| Error::<T, I>::NoProvider)?;
 			false
 		};
 		d.accounts = accounts;
@@ -60,7 +63,7 @@ impl<T: Config> Pallet<T> {
 	pub(super) fn dead_account(
 		what: T::AssetId,
 		who: &T::AccountId,
-		d: &mut AssetDetails<T::Balance, T::AccountId, DepositBalanceOf<T>>,
+		d: &mut AssetDetails<T::Balance, T::AccountId, DepositBalanceOf<T, I>>,
 		sufficient: bool,
 	) {
 		if sufficient {
@@ -73,15 +76,19 @@ impl<T: Config> Pallet<T> {
 		T::Freezer::died(what, who)
 	}
 
-	pub(super) fn can_increase(id: T::AssetId, who: &T::AccountId, amount: T::Balance) -> DepositConsequence {
-		let details = match Asset::<T>::get(id) {
+	pub(super) fn can_increase(
+		id: T::AssetId,
+		who: &T::AccountId,
+		amount: T::Balance,
+	) -> DepositConsequence {
+		let details = match Asset::<T, I>::get(id) {
 			Some(details) => details,
 			None => return DepositConsequence::UnknownAsset,
 		};
 		if details.supply.checked_add(&amount).is_none() {
 			return DepositConsequence::Overflow
 		}
-		let account = Account::<T>::get(id, who);
+		let account = Account::<T, I>::get(id, who);
 		if account.balance.checked_add(&amount).is_none() {
 			return DepositConsequence::Overflow
 		}
@@ -108,7 +115,7 @@ impl<T: Config> Pallet<T> {
 		keep_alive: bool,
 	) -> WithdrawConsequence<T::Balance> {
 		use WithdrawConsequence::*;
-		let details = match Asset::<T>::get(id) {
+		let details = match Asset::<T, I>::get(id) {
 			Some(details) => details,
 			None => return UnknownAsset,
 		};
@@ -118,7 +125,7 @@ impl<T: Config> Pallet<T> {
 		if details.is_frozen {
 			return Frozen
 		}
-		let account = Account::<T>::get(id, who);
+		let account = Account::<T, I>::get(id, who);
 		if account.is_frozen {
 			return Frozen
 		}
@@ -155,19 +162,21 @@ impl<T: Config> Pallet<T> {
 		id: T::AssetId,
 		who: &T::AccountId,
 		keep_alive: bool,
-	) -> Result<T::Balance, Error<T>> {
-		let details = match Asset::<T>::get(id) {
+	) -> Result<T::Balance, Error<T, I>> {
+		let details = match Asset::<T, I>::get(id) {
 			Some(details) => details,
-			None => return Err(Error::<T>::Unknown),
+			None => return Err(Error::<T, I>::Unknown),
 		};
-		ensure!(!details.is_frozen, Error::<T>::Frozen);
+		ensure!(!details.is_frozen, Error::<T, I>::Frozen);
 
-		let account = Account::<T>::get(id, who);
-		ensure!(!account.is_frozen, Error::<T>::Frozen);
+		let account = Account::<T, I>::get(id, who);
+		ensure!(!account.is_frozen, Error::<T, I>::Frozen);
 
 		let amount = if let Some(frozen) = T::Freezer::frozen_balance(id, who) {
 			// Frozen balance: account CANNOT be deleted
-			let required = frozen.checked_add(&details.min_balance).ok_or(Error::<T>::Overflow)?;
+			let required = frozen
+				.checked_add(&details.min_balance)
+				.ok_or(Error::<T, I>::Overflow)?;
 			account.balance.saturating_sub(required)
 		} else {
 			let is_provider = false;
@@ -204,9 +213,8 @@ impl<T: Config> Pallet<T> {
 		amount: T::Balance,
 		f: DebitFlags,
 	) -> Result<T::Balance, DispatchError> {
-		let actual = Self::reducible_balance(id, target, f.keep_alive)?
-			.min(amount);
-		ensure!(f.best_effort || actual >= amount, Error::<T>::BalanceLow);
+		let actual = Self::reducible_balance(id, target, f.keep_alive)?.min(amount);
+		ensure!(f.best_effort || actual >= amount, Error::<T, I>::BalanceLow);
 
 		let conseq = Self::can_decrease(id, target, actual, f.keep_alive);
 		let actual = match conseq.into_result() {
@@ -263,7 +271,10 @@ impl<T: Config> Pallet<T> {
 	) -> DispatchResult {
 		Self::increase_balance(id, beneficiary, amount, |details| -> DispatchResult {
 			if let Some(check_issuer) = maybe_check_issuer {
-				ensure!(&check_issuer == &details.issuer, Error::<T>::NoPermission);
+				ensure!(
+					&check_issuer == &details.issuer,
+					Error::<T, I>::NoPermission
+				);
 			}
 			debug_assert!(T::Balance::max_value() - details.supply >= amount, "checked in prep; qed");
 			details.supply = details.supply.saturating_add(amount);
@@ -283,17 +294,19 @@ impl<T: Config> Pallet<T> {
 		id: T::AssetId,
 		beneficiary: &T::AccountId,
 		amount: T::Balance,
-		check: impl FnOnce(&mut AssetDetails<T::Balance, T::AccountId, DepositBalanceOf<T>>) -> DispatchResult,
+		check: impl FnOnce(
+			&mut AssetDetails<T::Balance, T::AccountId, DepositBalanceOf<T, I>>,
+		) -> DispatchResult,
 	) -> DispatchResult {
 		if amount.is_zero() { return Ok(()) }
 
 		Self::can_increase(id, beneficiary, amount).into_result()?;
-		Asset::<T>::try_mutate(id, |maybe_details| -> DispatchResult {
-			let details = maybe_details.as_mut().ok_or(Error::<T>::Unknown)?;
+		Asset::<T, I>::try_mutate(id, |maybe_details| -> DispatchResult {
+			let details = maybe_details.as_mut().ok_or(Error::<T, I>::Unknown)?;
 
 			check(details)?;
 
-			Account::<T>::try_mutate(id, beneficiary, |t| -> DispatchResult {
+			Account::<T, I>::try_mutate(id, beneficiary, |t| -> DispatchResult {
 				let new_balance = t.balance.saturating_add(amount);
 				ensure!(new_balance >= details.min_balance, TokenError::BelowMinimum);
 				if t.balance.is_zero() {
@@ -324,7 +337,7 @@ impl<T: Config> Pallet<T> {
 		let actual = Self::decrease_balance(id, target, amount, f, |actual, details| {
 			// Check admin rights.
 			if let Some(check_admin) = maybe_check_admin {
-				ensure!(&check_admin == &details.admin, Error::<T>::NoPermission);
+				ensure!(&check_admin == &details.admin, Error::<T, I>::NoPermission);
 			}
 
 			debug_assert!(details.supply >= actual, "checked in prep; qed");
@@ -351,19 +364,19 @@ impl<T: Config> Pallet<T> {
 		f: DebitFlags,
 		check: impl FnOnce(
 			T::Balance,
-			&mut AssetDetails<T::Balance, T::AccountId, DepositBalanceOf<T>>,
+			&mut AssetDetails<T::Balance, T::AccountId, DepositBalanceOf<T, I>>,
 		) -> DispatchResult,
 	) -> Result<T::Balance, DispatchError> {
 		if amount.is_zero() { return Ok(amount) }
 
 		let actual = Self::prep_debit(id, target, amount, f)?;
 
-		Asset::<T>::try_mutate(id, |maybe_details| -> DispatchResult {
-			let details = maybe_details.as_mut().ok_or(Error::<T>::Unknown)?;
+		Asset::<T, I>::try_mutate(id, |maybe_details| -> DispatchResult {
+			let details = maybe_details.as_mut().ok_or(Error::<T, I>::Unknown)?;
 
 			check(actual, details)?;
 
-			Account::<T>::try_mutate_exists(id, target, |maybe_account| -> DispatchResult {
+			Account::<T, I>::try_mutate_exists(id, target, |maybe_account| -> DispatchResult {
 				let mut account = maybe_account.take().unwrap_or_default();
 				debug_assert!(account.balance >= actual, "checked in prep; qed");
 
@@ -411,14 +424,14 @@ impl<T: Config> Pallet<T> {
 		let debit = Self::prep_debit(id, &source, amount, f.into())?;
 		let (credit, maybe_burn) = Self::prep_credit(id, &dest, amount, debit, f.burn_dust)?;
 
-		let mut source_account = Account::<T>::get(id, &source);
+		let mut source_account = Account::<T, I>::get(id, &source);
 
-		Asset::<T>::try_mutate(id, |maybe_details| -> DispatchResult {
-			let details = maybe_details.as_mut().ok_or(Error::<T>::Unknown)?;
+		Asset::<T, I>::try_mutate(id, |maybe_details| -> DispatchResult {
+			let details = maybe_details.as_mut().ok_or(Error::<T, I>::Unknown)?;
 
 			// Check admin rights.
 			if let Some(need_admin) = maybe_need_admin {
-				ensure!(&need_admin == &details.admin, Error::<T>::NoPermission);
+				ensure!(&need_admin == &details.admin, Error::<T, I>::NoPermission);
 			}
 
 			// Skip if source == dest
@@ -437,7 +450,7 @@ impl<T: Config> Pallet<T> {
 			debug_assert!(source_account.balance >= debit, "checked in prep; qed");
 			source_account.balance = source_account.balance.saturating_sub(debit);
 
-			Account::<T>::try_mutate(id, &dest, |a| -> DispatchResult {
+			Account::<T, I>::try_mutate(id, &dest, |a| -> DispatchResult {
 				// Calculate new balance; this will not saturate since it's already checked in prep.
 				debug_assert!(a.balance.checked_add(&credit).is_some(), "checked in prep; qed");
 				let new_balance = a.balance.saturating_add(credit);
@@ -455,9 +468,9 @@ impl<T: Config> Pallet<T> {
 			if source_account.balance < details.min_balance {
 				debug_assert!(source_account.balance.is_zero(), "checked in prep; qed");
 				Self::dead_account(id, &source, details, source_account.sufficient);
-				Account::<T>::remove(id, &source);
+				Account::<T, I>::remove(id, &source);
 			} else {
-				Account::<T>::insert(id, &source, &source_account)
+				Account::<T, I>::insert(id, &source, &source_account)
 			}
 
 			Ok(())

substrate/frame/assets/src/impl_fungibles.rs

@@ -19,23 +19,24 @@
 
 use super::*;
 
-impl<T: Config> fungibles::Inspect<<T as SystemConfig>::AccountId> for Pallet<T> {
+impl<T: Config<I>, I: 'static> fungibles::Inspect<<T as SystemConfig>::AccountId> for Pallet<T, I> {
 	type AssetId = T::AssetId;
 	type Balance = T::Balance;
 
 	fn total_issuance(asset: Self::AssetId) -> Self::Balance {
-		Asset::<T>::get(asset).map(|x| x.supply).unwrap_or_else(Zero::zero)
+		Asset::<T, I>::get(asset)
+			.map(|x| x.supply)
+			.unwrap_or_else(Zero::zero)
 	}
 
 	fn minimum_balance(asset: Self::AssetId) -> Self::Balance {
-		Asset::<T>::get(asset).map(|x| x.min_balance).unwrap_or_else(Zero::zero)
+		Asset::<T, I>::get(asset)
+			.map(|x| x.min_balance)
+			.unwrap_or_else(Zero::zero)
 	}
 
-	fn balance(
-		asset: Self::AssetId,
-		who: &<T as SystemConfig>::AccountId,
-	) -> Self::Balance {
-		Pallet::<T>::balance(asset, who)
+	fn balance(asset: Self::AssetId, who: &<T as SystemConfig>::AccountId) -> Self::Balance {
+		Pallet::<T, I>::balance(asset, who)
 	}
 
 	fn reducible_balance(
@@ -43,7 +44,7 @@ impl<T: Config> fungibles::Inspect<<T as SystemConfig>::AccountId> for Pallet<T>
 		who: &<T as SystemConfig>::AccountId,
 		keep_alive: bool,
 	) -> Self::Balance {
-		Pallet::<T>::reducible_balance(asset, who, keep_alive).unwrap_or(Zero::zero())
+		Pallet::<T, I>::reducible_balance(asset, who, keep_alive).unwrap_or(Zero::zero())
 	}
 
 	fn can_deposit(
@@ -51,7 +52,7 @@ impl<T: Config> fungibles::Inspect<<T as SystemConfig>::AccountId> for Pallet<T>
 		who: &<T as SystemConfig>::AccountId,
 		amount: Self::Balance,
 	) -> DepositConsequence {
-		Pallet::<T>::can_increase(asset, who, amount)
+		Pallet::<T, I>::can_increase(asset, who, amount)
 	}
 
 	fn can_withdraw(
@@ -59,11 +60,11 @@ impl<T: Config> fungibles::Inspect<<T as SystemConfig>::AccountId> for Pallet<T>
 		who: &<T as SystemConfig>::AccountId,
 		amount: Self::Balance,
 	) -> WithdrawConsequence<Self::Balance> {
-		Pallet::<T>::can_decrease(asset, who, amount, false)
+		Pallet::<T, I>::can_decrease(asset, who, amount, false)
 	}
 }
 
-impl<T: Config> fungibles::Mutate<<T as SystemConfig>::AccountId> for Pallet<T> {
+impl<T: Config<I>, I: 'static> fungibles::Mutate<<T as SystemConfig>::AccountId> for Pallet<T, I> {
 	fn mint_into(
 		asset: Self::AssetId,
 		who: &<T as SystemConfig>::AccountId,
@@ -97,7 +98,7 @@ impl<T: Config> fungibles::Mutate<<T as SystemConfig>::AccountId> for Pallet<T>
 	}
 }
 
-impl<T: Config> fungibles::Transfer<T::AccountId> for Pallet<T> {
+impl<T: Config<I>, I: 'static> fungibles::Transfer<T::AccountId> for Pallet<T, I> {
 	fn transfer(
 		asset: Self::AssetId,
 		source: &T::AccountId,
@@ -114,13 +115,15 @@ impl<T: Config> fungibles::Transfer<T::AccountId> for Pallet<T> {
 	}
 }
 
-impl<T: Config> fungibles::Unbalanced<T::AccountId> for Pallet<T> {
+impl<T: Config<I>, I: 'static> fungibles::Unbalanced<T::AccountId> for Pallet<T, I> {
 	fn set_balance(_: Self::AssetId, _: &T::AccountId, _: Self::Balance) -> DispatchResult {
 		unreachable!("set_balance is not used if other functions are impl'd");
 	}
 	fn set_total_issuance(id: T::AssetId, amount: Self::Balance) {
-		Asset::<T>::mutate_exists(id, |maybe_asset| if let Some(ref mut asset) = maybe_asset {
-			asset.supply = amount
+		Asset::<T, I>::mutate_exists(id, |maybe_asset| {
+			if let Some(ref mut asset) = maybe_asset {
+				asset.supply = amount
+			}
 		});
 	}
 	fn decrease_balance(asset: T::AssetId, who: &T::AccountId, amount: Self::Balance)

substrate/frame/assets/src/impl_stored_map.rs

@@ -19,11 +19,11 @@
 
 use super::*;
 
-impl<T: Config> StoredMap<(T::AssetId, T::AccountId), T::Extra> for Pallet<T> {
+impl<T: Config<I>, I: 'static> StoredMap<(T::AssetId, T::AccountId), T::Extra> for Pallet<T, I> {
 	fn get(id_who: &(T::AssetId, T::AccountId)) -> T::Extra {
 		let &(id, ref who) = id_who;
-		if Account::<T>::contains_key(id, who) {
-			Account::<T>::get(id, who).extra
+		if Account::<T, I>::contains_key(id, who) {
+			Account::<T, I>::get(id, who).extra
 		} else {
 			Default::default()
 		}
@@ -34,13 +34,13 @@ impl<T: Config> StoredMap<(T::AssetId, T::AccountId), T::Extra> for Pallet<T> {
 		f: impl FnOnce(&mut Option<T::Extra>) -> Result<R, E>,
 	) -> Result<R, E> {
 		let &(id, ref who) = id_who;
-		let mut maybe_extra = Some(Account::<T>::get(id, who).extra);
+		let mut maybe_extra = Some(Account::<T, I>::get(id, who).extra);
 		let r = f(&mut maybe_extra)?;
 		// They want to write some value or delete it.
 		// If the account existed and they want to write a value, then we write.
 		// If the account didn't exist and they want to delete it, then we let it pass.
 		// Otherwise, we fail.
-		Account::<T>::try_mutate_exists(id, who, |maybe_account| {
+		Account::<T, I>::try_mutate_exists(id, who, |maybe_account| {
 			if let Some(extra) = maybe_extra {
 				// They want to write a value. Let this happen only if the account actually exists.
 				if let Some(ref mut account) = maybe_account {

substrate/frame/assets/src/lib.rs

@@ -165,13 +165,13 @@ pub mod pallet {
 
 	#[pallet::pallet]
 	#[pallet::generate_store(pub(super) trait Store)]
-	pub struct Pallet<T>(_);
+	pub struct Pallet<T, I = ()>(_);
 
 	#[pallet::config]
 	/// The module configuration trait.
-	pub trait Config: frame_system::Config {
+	pub trait Config<I: 'static = ()>: frame_system::Config {
 		/// The overarching event type.
-		type Event: From<Event<Self>> + IsType<<Self as frame_system::Config>::Event>;
+		type Event: From<Event<Self, I>> + IsType<<Self as frame_system::Config>::Event>;
 
 		/// The units in which we record balances.
 		type Balance: Member + Parameter + AtLeast32BitUnsigned + Default + Copy;
@@ -187,17 +187,17 @@ pub mod pallet {
 		type ForceOrigin: EnsureOrigin<Self::Origin>;
 
 		/// The basic amount of funds that must be reserved for an asset.
-		type AssetDeposit: Get<DepositBalanceOf<Self>>;
+		type AssetDeposit: Get<DepositBalanceOf<Self, I>>;
 
 		/// The basic amount of funds that must be reserved when adding metadata to your asset.
-		type MetadataDepositBase: Get<DepositBalanceOf<Self>>;
+		type MetadataDepositBase: Get<DepositBalanceOf<Self, I>>;
 
 		/// The additional funds that must be reserved for the number of bytes you store in your
 		/// metadata.
-		type MetadataDepositPerByte: Get<DepositBalanceOf<Self>>;
+		type MetadataDepositPerByte: Get<DepositBalanceOf<Self, I>>;
 
 		/// The amount of funds that must be reserved when creating a new approval.
-		type ApprovalDeposit: Get<DepositBalanceOf<Self>>;
+		type ApprovalDeposit: Get<DepositBalanceOf<Self, I>>;
 
 		/// The maximum length of a name or symbol stored on-chain.
 		type StringLimit: Get<u32>;
@@ -215,16 +215,16 @@ pub mod pallet {
 
 	#[pallet::storage]
 	/// Details of an asset.
-	pub(super) type Asset<T: Config> = StorageMap<
+	pub(super) type Asset<T: Config<I>, I: 'static = ()> = StorageMap<
 		_,
 		Blake2_128Concat,
 		T::AssetId,
-		AssetDetails<T::Balance, T::AccountId, DepositBalanceOf<T>>,
+		AssetDetails<T::Balance, T::AccountId, DepositBalanceOf<T, I>>,
 	>;
 
 	#[pallet::storage]
 	/// The number of units of assets held by any given account.
-	pub(super) type Account<T: Config> = StorageDoubleMap<
+	pub(super) type Account<T: Config<I>, I: 'static = ()> = StorageDoubleMap<
 		_,
 		Blake2_128Concat,
 		T::AssetId,
@@ -237,30 +237,34 @@ pub mod pallet {
 	#[pallet::storage]
 	/// Approved balance transfers. First balance is the amount approved for transfer. Second
 	/// is the amount of `T::Currency` reserved for storing this.
-	pub(super) type Approvals<T: Config> = StorageDoubleMap<
+	pub(super) type Approvals<T: Config<I>, I: 'static = ()> = StorageDoubleMap<
 		_,
 		Blake2_128Concat,
 		T::AssetId,
 		Blake2_128Concat,
 		ApprovalKey<T::AccountId>,
-		Approval<T::Balance, DepositBalanceOf<T>>,
+		Approval<T::Balance, DepositBalanceOf<T, I>>,
 		OptionQuery,
 	>;
 
 	#[pallet::storage]
 	/// Metadata of an asset.
-	pub(super) type Metadata<T: Config> = StorageMap<
+	pub(super) type Metadata<T: Config<I>, I: 'static = ()> = StorageMap<
 		_,
 		Blake2_128Concat,
 		T::AssetId,
-		AssetMetadata<DepositBalanceOf<T>>,
+		AssetMetadata<DepositBalanceOf<T, I>>,
 		ValueQuery,
 	>;
 
 	#[pallet::event]
 	#[pallet::generate_deposit(pub(super) fn deposit_event)]
-	#[pallet::metadata(T::AccountId = "AccountId", T::Balance = "Balance", T::AssetId = "AssetId")]
-	pub enum Event<T: Config> {
+	#[pallet::metadata(
+		T::AccountId = "AccountId",
+		T::Balance = "Balance",
+		T::AssetId = "AssetId"
+	)]
+	pub enum Event<T: Config<I>, I: 'static = ()> {
 		/// Some asset class was created. \[asset_id, creator, owner\]
 		Created(T::AssetId, T::AccountId, T::AccountId),
 		/// Some assets were issued. \[asset_id, owner, total_supply\]
@@ -305,7 +309,7 @@ pub mod pallet {
 	}
 
 	#[pallet::error]
-	pub enum Error<T> {
+	pub enum Error<T, I = ()> {
 		/// Account balance must be greater than or equal to the transfer amount.
 		BalanceLow,
 		/// Balance should be non-zero.
@@ -335,10 +339,10 @@ pub mod pallet {
 	}
 
 	#[pallet::hooks]
-	impl<T: Config> Hooks<BlockNumberFor<T>> for Pallet<T> {}
+	impl<T: Config<I>, I: 'static> Hooks<BlockNumberFor<T>> for Pallet<T, I> {}
 
 	#[pallet::call]
-	impl<T: Config> Pallet<T> {
+	impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		/// Issue a new class of fungible assets from a public origin.
 		///
 		/// This new asset class has no assets initially and its owner is the origin.
@@ -368,26 +372,29 @@ pub mod pallet {
 			let owner = ensure_signed(origin)?;
 			let admin = T::Lookup::lookup(admin)?;
 
-			ensure!(!Asset::<T>::contains_key(id), Error::<T>::InUse);
-			ensure!(!min_balance.is_zero(), Error::<T>::MinBalanceZero);
+			ensure!(!Asset::<T, I>::contains_key(id), Error::<T, I>::InUse);
+			ensure!(!min_balance.is_zero(), Error::<T, I>::MinBalanceZero);
 
 			let deposit = T::AssetDeposit::get();
 			T::Currency::reserve(&owner, deposit)?;
 
-			Asset::<T>::insert(id, AssetDetails {
-				owner: owner.clone(),
-				issuer: admin.clone(),
-				admin: admin.clone(),
-				freezer: admin.clone(),
-				supply: Zero::zero(),
-				deposit,
-				min_balance,
-				is_sufficient: false,
-				accounts: 0,
-				sufficients: 0,
-				approvals: 0,
-				is_frozen: false,
-			});
+			Asset::<T, I>::insert(
+				id,
+				AssetDetails {
+					owner: owner.clone(),
+					issuer: admin.clone(),
+					admin: admin.clone(),
+					freezer: admin.clone(),
+					supply: Zero::zero(),
+					deposit,
+					min_balance,
+					is_sufficient: false,
+					accounts: 0,
+					sufficients: 0,
+					approvals: 0,
+					is_frozen: false,
+				},
+			);
 			Self::deposit_event(Event::Created(id, owner, admin));
 			Ok(())
 		}
@@ -424,23 +431,26 @@ pub mod pallet {
 			T::ForceOrigin::ensure_origin(origin)?;
 			let owner = T::Lookup::lookup(owner)?;
 
-			ensure!(!Asset::<T>::contains_key(id), Error::<T>::InUse);
-			ensure!(!min_balance.is_zero(), Error::<T>::MinBalanceZero);
+			ensure!(!Asset::<T, I>::contains_key(id), Error::<T, I>::InUse);
+			ensure!(!min_balance.is_zero(), Error::<T, I>::MinBalanceZero);
 
-			Asset::<T>::insert(id, AssetDetails {
-				owner: owner.clone(),
-				issuer: owner.clone(),
-				admin: owner.clone(),
-				freezer: owner.clone(),
-				supply: Zero::zero(),
-				deposit: Zero::zero(),
-				min_balance,
-				is_sufficient,
-				accounts: 0,
-				sufficients: 0,
-				approvals: 0,
-				is_frozen: false,
-			});
+			Asset::<T, I>::insert(
+				id,
+				AssetDetails {
+					owner: owner.clone(),
+					issuer: owner.clone(),
+					admin: owner.clone(),
+					freezer: owner.clone(),
+					supply: Zero::zero(),
+					deposit: Zero::zero(),
+					min_balance,
+					is_sufficient,
+					accounts: 0,
+					sufficients: 0,
+					approvals: 0,
+					is_frozen: false,
+				},
+			);
 			Self::deposit_event(Event::ForceCreated(id, owner));
 			Ok(())
 		}
@@ -473,25 +483,28 @@ pub mod pallet {
 				Ok(_) => None,
 				Err(origin) => Some(ensure_signed(origin)?),
 			};
-			Asset::<T>::try_mutate_exists(id, |maybe_details| {
-				let mut details = maybe_details.take().ok_or(Error::<T>::Unknown)?;
+			Asset::<T, I>::try_mutate_exists(id, |maybe_details| {
+				let mut details = maybe_details.take().ok_or(Error::<T, I>::Unknown)?;
 				if let Some(check_owner) = maybe_check_owner {
-					ensure!(details.owner == check_owner, Error::<T>::NoPermission);
+					ensure!(details.owner == check_owner, Error::<T, I>::NoPermission);
 				}
-				ensure!(details.accounts == witness.accounts, Error::<T>::BadWitness);
-				ensure!(details.sufficients == witness.sufficients, Error::<T>::BadWitness);
-				ensure!(details.approvals == witness.approvals, Error::<T>::BadWitness);
+				ensure!(details.accounts == witness.accounts, Error::<T, I>::BadWitness);
+				ensure!(details.sufficients == witness.sufficients, Error::<T, I>::BadWitness);
+				ensure!(details.approvals == witness.approvals, Error::<T, I>::BadWitness);
 
-				for (who, v) in Account::<T>::drain_prefix(id) {
+				for (who, v) in Account::<T, I>::drain_prefix(id) {
 					Self::dead_account(id, &who, &mut details, v.sufficient);
 				}
 				debug_assert_eq!(details.accounts, 0);
 				debug_assert_eq!(details.sufficients, 0);
 
-				let metadata = Metadata::<T>::take(&id);
-				T::Currency::unreserve(&details.owner, details.deposit.saturating_add(metadata.deposit));
+				let metadata = Metadata::<T, I>::take(&id);
+				T::Currency::unreserve(
+					&details.owner,
+					details.deposit.saturating_add(metadata.deposit),
+				);
 
-				Approvals::<T>::remove_prefix(&id);
+				Approvals::<T, I>::remove_prefix(&id);
 				Self::deposit_event(Event::Destroyed(id));
 
 				// NOTE: could use postinfo to reflect the actual number of accounts/sufficient/approvals
@@ -685,14 +698,17 @@ pub mod pallet {
 		) -> DispatchResult {
 			let origin = ensure_signed(origin)?;
 
-			let d = Asset::<T>::get(id).ok_or(Error::<T>::Unknown)?;
-			ensure!(&origin == &d.freezer, Error::<T>::NoPermission);
+			let d = Asset::<T, I>::get(id).ok_or(Error::<T, I>::Unknown)?;
+			ensure!(&origin == &d.freezer, Error::<T, I>::NoPermission);
 			let who = T::Lookup::lookup(who)?;
-			ensure!(Account::<T>::contains_key(id, &who), Error::<T>::BalanceZero);
+			ensure!(
+				Account::<T, I>::contains_key(id, &who),
+				Error::<T, I>::BalanceZero
+			);
 
-			Account::<T>::mutate(id, &who, |a| a.is_frozen = true);
+			Account::<T, I>::mutate(id, &who, |a| a.is_frozen = true);
 
-			Self::deposit_event(Event::<T>::Frozen(id, who));
+			Self::deposit_event(Event::<T, I>::Frozen(id, who));
 			Ok(())
 		}
 
@@ -715,14 +731,17 @@ pub mod pallet {
 		) -> DispatchResult {
 			let origin = ensure_signed(origin)?;
 
-			let details = Asset::<T>::get(id).ok_or(Error::<T>::Unknown)?;
-			ensure!(&origin == &details.admin, Error::<T>::NoPermission);
+			let details = Asset::<T, I>::get(id).ok_or(Error::<T, I>::Unknown)?;
+			ensure!(&origin == &details.admin, Error::<T, I>::NoPermission);
 			let who = T::Lookup::lookup(who)?;
-			ensure!(Account::<T>::contains_key(id, &who), Error::<T>::BalanceZero);
+			ensure!(
+				Account::<T, I>::contains_key(id, &who),
+				Error::<T, I>::BalanceZero
+			);
 
-			Account::<T>::mutate(id, &who, |a| a.is_frozen = false);
+			Account::<T, I>::mutate(id, &who, |a| a.is_frozen = false);
 
-			Self::deposit_event(Event::<T>::Thawed(id, who));
+			Self::deposit_event(Event::<T, I>::Thawed(id, who));
 			Ok(())
 		}
 
@@ -742,13 +761,13 @@ pub mod pallet {
 		) -> DispatchResult {
 			let origin = ensure_signed(origin)?;
 
-			Asset::<T>::try_mutate(id, |maybe_details| {
-				let d = maybe_details.as_mut().ok_or(Error::<T>::Unknown)?;
-				ensure!(&origin == &d.freezer, Error::<T>::NoPermission);
+			Asset::<T, I>::try_mutate(id, |maybe_details| {
+				let d = maybe_details.as_mut().ok_or(Error::<T, I>::Unknown)?;
+				ensure!(&origin == &d.freezer, Error::<T, I>::NoPermission);
 
 				d.is_frozen = true;
 
-				Self::deposit_event(Event::<T>::AssetFrozen(id));
+				Self::deposit_event(Event::<T, I>::AssetFrozen(id));
 				Ok(())
 			})
 		}
@@ -769,13 +788,13 @@ pub mod pallet {
 		) -> DispatchResult {
 			let origin = ensure_signed(origin)?;
 
-			Asset::<T>::try_mutate(id, |maybe_details| {
-				let d = maybe_details.as_mut().ok_or(Error::<T>::Unknown)?;
-				ensure!(&origin == &d.admin, Error::<T>::NoPermission);
+			Asset::<T, I>::try_mutate(id, |maybe_details| {
+				let d = maybe_details.as_mut().ok_or(Error::<T, I>::Unknown)?;
+				ensure!(&origin == &d.admin, Error::<T, I>::NoPermission);
 
 				d.is_frozen = false;
 
-				Self::deposit_event(Event::<T>::AssetThawed(id));
+				Self::deposit_event(Event::<T, I>::AssetThawed(id));
 				Ok(())
 			})
 		}
@@ -799,12 +818,14 @@ pub mod pallet {
 			let origin = ensure_signed(origin)?;
 			let owner = T::Lookup::lookup(owner)?;
 
-			Asset::<T>::try_mutate(id, |maybe_details| {
-				let details = maybe_details.as_mut().ok_or(Error::<T>::Unknown)?;
-				ensure!(&origin == &details.owner, Error::<T>::NoPermission);
-				if details.owner == owner { return Ok(()) }
+			Asset::<T, I>::try_mutate(id, |maybe_details| {
+				let details = maybe_details.as_mut().ok_or(Error::<T, I>::Unknown)?;
+				ensure!(&origin == &details.owner, Error::<T, I>::NoPermission);
+				if details.owner == owner {
+					return Ok(());
+				}
 
-				let metadata_deposit = Metadata::<T>::get(id).deposit;
+				let metadata_deposit = Metadata::<T, I>::get(id).deposit;
 				let deposit = details.deposit + metadata_deposit;
 
 				// Move the deposit to the new owner.
@@ -842,9 +863,9 @@ pub mod pallet {
 			let admin = T::Lookup::lookup(admin)?;
 			let freezer = T::Lookup::lookup(freezer)?;
 
-			Asset::<T>::try_mutate(id, |maybe_details| {
-				let details = maybe_details.as_mut().ok_or(Error::<T>::Unknown)?;
-				ensure!(&origin == &details.owner, Error::<T>::NoPermission);
+			Asset::<T, I>::try_mutate(id, |maybe_details| {
+				let details = maybe_details.as_mut().ok_or(Error::<T, I>::Unknown)?;
+				ensure!(&origin == &details.owner, Error::<T, I>::NoPermission);
 
 				details.issuer = issuer.clone();
 				details.admin = admin.clone();
@@ -881,14 +902,17 @@ pub mod pallet {
 		) -> DispatchResult {
 			let origin = ensure_signed(origin)?;
 
-			ensure!(name.len() <= T::StringLimit::get() as usize, Error::<T>::BadMetadata);
-			ensure!(symbol.len() <= T::StringLimit::get() as usize, Error::<T>::BadMetadata);
+			ensure!(name.len() <= T::StringLimit::get() as usize, Error::<T, I>::BadMetadata);
+			ensure!(symbol.len() <= T::StringLimit::get() as usize, Error::<T, I>::BadMetadata);
 
-			let d = Asset::<T>::get(id).ok_or(Error::<T>::Unknown)?;
-			ensure!(&origin == &d.owner, Error::<T>::NoPermission);
+			let d = Asset::<T, I>::get(id).ok_or(Error::<T, I>::Unknown)?;
+			ensure!(&origin == &d.owner, Error::<T, I>::NoPermission);
 
-			Metadata::<T>::try_mutate_exists(id, |metadata| {
-				ensure!(metadata.as_ref().map_or(true, |m| !m.is_frozen), Error::<T>::NoPermission);
+			Metadata::<T, I>::try_mutate_exists(id, |metadata| {
+				ensure!(
+					metadata.as_ref().map_or(true, |m| !m.is_frozen),
+					Error::<T, I>::NoPermission
+				);
 
 				let old_deposit = metadata.take().map_or(Zero::zero(), |m| m.deposit);
 				let new_deposit = T::MetadataDepositPerByte::get()
@@ -932,11 +956,11 @@ pub mod pallet {
 		) -> DispatchResult {
 			let origin = ensure_signed(origin)?;
 
-			let d = Asset::<T>::get(id).ok_or(Error::<T>::Unknown)?;
-			ensure!(&origin == &d.owner, Error::<T>::NoPermission);
+			let d = Asset::<T, I>::get(id).ok_or(Error::<T, I>::Unknown)?;
+			ensure!(&origin == &d.owner, Error::<T, I>::NoPermission);
 
-			Metadata::<T>::try_mutate_exists(id, |metadata| {
-				let deposit = metadata.take().ok_or(Error::<T>::Unknown)?.deposit;
+			Metadata::<T, I>::try_mutate_exists(id, |metadata| {
+				let deposit = metadata.take().ok_or(Error::<T, I>::Unknown)?.deposit;
 				T::Currency::unreserve(&d.owner, deposit);
 				Self::deposit_event(Event::MetadataCleared(id));
 				Ok(())
@@ -968,11 +992,11 @@ pub mod pallet {
 		) -> DispatchResult {
 			T::ForceOrigin::ensure_origin(origin)?;
 
-			ensure!(name.len() <= T::StringLimit::get() as usize, Error::<T>::BadMetadata);
-			ensure!(symbol.len() <= T::StringLimit::get() as usize, Error::<T>::BadMetadata);
+			ensure!(name.len() <= T::StringLimit::get() as usize, Error::<T, I>::BadMetadata);
+			ensure!(symbol.len() <= T::StringLimit::get() as usize, Error::<T, I>::BadMetadata);
 
-			ensure!(Asset::<T>::contains_key(id), Error::<T>::Unknown);
-			Metadata::<T>::try_mutate_exists(id, |metadata| {
+			ensure!(Asset::<T, I>::contains_key(id), Error::<T, I>::Unknown);
+			Metadata::<T, I>::try_mutate_exists(id, |metadata| {
 				let deposit = metadata.take().map_or(Zero::zero(), |m| m.deposit);
 				*metadata = Some(AssetMetadata {
 					deposit,
@@ -1005,9 +1029,9 @@ pub mod pallet {
 		) -> DispatchResult {
 			T::ForceOrigin::ensure_origin(origin)?;
 
-			let d = Asset::<T>::get(id).ok_or(Error::<T>::Unknown)?;
-			Metadata::<T>::try_mutate_exists(id, |metadata| {
-				let deposit = metadata.take().ok_or(Error::<T>::Unknown)?.deposit;
+			let d = Asset::<T, I>::get(id).ok_or(Error::<T, I>::Unknown)?;
+			Metadata::<T, I>::try_mutate_exists(id, |metadata| {
+				let deposit = metadata.take().ok_or(Error::<T, I>::Unknown)?.deposit;
 				T::Currency::unreserve(&d.owner, deposit);
 				Self::deposit_event(Event::MetadataCleared(id));
 				Ok(())
@@ -1050,8 +1074,8 @@ pub mod pallet {
 		) -> DispatchResult {
 			T::ForceOrigin::ensure_origin(origin)?;
 
-			Asset::<T>::try_mutate(id, |maybe_asset| {
-				let mut asset = maybe_asset.take().ok_or(Error::<T>::Unknown)?;
+			Asset::<T, I>::try_mutate(id, |maybe_asset| {
+				let mut asset = maybe_asset.take().ok_or(Error::<T, I>::Unknown)?;
 				asset.owner = T::Lookup::lookup(owner)?;
 				asset.issuer = T::Lookup::lookup(issuer)?;
 				asset.admin = T::Lookup::lookup(admin)?;
@@ -1097,7 +1121,7 @@ pub mod pallet {
 			let delegate = T::Lookup::lookup(delegate)?;
 
 			let key = ApprovalKey { owner, delegate };
-			Approvals::<T>::try_mutate(id, &key, |maybe_approved| -> DispatchResult {
+			Approvals::<T, I>::try_mutate(id, &key, |maybe_approved| -> DispatchResult {
 				let mut approved = maybe_approved.take().unwrap_or_default();
 				let deposit_required = T::ApprovalDeposit::get();
 				if approved.deposit < deposit_required {
@@ -1135,7 +1159,7 @@ pub mod pallet {
 			let owner = ensure_signed(origin)?;
 			let delegate = T::Lookup::lookup(delegate)?;
 			let key = ApprovalKey { owner, delegate };
-			let approval = Approvals::<T>::take(id, &key).ok_or(Error::<T>::Unknown)?;
+			let approval = Approvals::<T, I>::take(id, &key).ok_or(Error::<T, I>::Unknown)?;
 			T::Currency::unreserve(&key.owner, approval.deposit);
 
 			Self::deposit_event(Event::ApprovalCancelled(id, key.owner, key.delegate));
@@ -1166,8 +1190,8 @@ pub mod pallet {
 				.map(|_| ())
 				.or_else(|origin| -> DispatchResult {
 					let origin = ensure_signed(origin)?;
-					let d = Asset::<T>::get(id).ok_or(Error::<T>::Unknown)?;
-					ensure!(&origin == &d.admin, Error::<T>::NoPermission);
+					let d = Asset::<T, I>::get(id).ok_or(Error::<T, I>::Unknown)?;
+					ensure!(&origin == &d.admin, Error::<T, I>::NoPermission);
 					Ok(())
 				})?;
 
@@ -1175,7 +1199,7 @@ pub mod pallet {
 			let delegate = T::Lookup::lookup(delegate)?;
 
 			let key = ApprovalKey { owner, delegate };
-			let approval = Approvals::<T>::take(id, &key).ok_or(Error::<T>::Unknown)?;
+			let approval = Approvals::<T, I>::take(id, &key).ok_or(Error::<T, I>::Unknown)?;
 			T::Currency::unreserve(&key.owner, approval.deposit);
 
 			Self::deposit_event(Event::ApprovalCancelled(id, key.owner, key.delegate));
@@ -1213,9 +1237,12 @@ pub mod pallet {
 			let destination = T::Lookup::lookup(destination)?;
 
 			let key = ApprovalKey { owner, delegate };
-			Approvals::<T>::try_mutate_exists(id, &key, |maybe_approved| -> DispatchResult {
-				let mut approved = maybe_approved.take().ok_or(Error::<T>::Unapproved)?;
-				let remaining = approved.amount.checked_sub(&amount).ok_or(Error::<T>::Unapproved)?;
+			Approvals::<T, I>::try_mutate_exists(id, &key, |maybe_approved| -> DispatchResult {
+				let mut approved = maybe_approved.take().ok_or(Error::<T, I>::Unapproved)?;
+				let remaining = approved
+					.amount
+					.checked_sub(&amount)
+					.ok_or(Error::<T, I>::Unapproved)?;
 
 				let f = TransferFlags {
 					keep_alive: false,

substrate/frame/assets/src/types.rs

@@ -15,11 +15,12 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//! Various basic tyoes for use in the assets pallet.
+//! Various basic types for use in the assets pallet.
 
 use super::*;
 
-pub(super) type DepositBalanceOf<T> = <<T as Config>::Currency as Currency<<T as SystemConfig>::AccountId>>::Balance;
+pub(super) type DepositBalanceOf<T, I = ()> =
+	<<T as Config<I>>::Currency as Currency<<T as SystemConfig>::AccountId>>::Balance;
 
 #[derive(Clone, Encode, Decode, Eq, PartialEq, RuntimeDebug)]
 pub struct AssetDetails<