Implement holds and freezes in orml-tokens.

[TorstenStueber]

The latest Polkadot release (v0.9.42) added two new traits to the Fungibles family: hold and freeze (which has been added in paritytech/substrate#12951).

It would be very helpful if the tokens pallet also implement this additional Fungibles traits. At least for the hold trait it should be possible to use the underlying reserve mechanism.

[Chralt98]

Regarding holds and freezes: Will anything change for the interface of orml_currencies? Or is it completely abstracted away and we can use reserve_named and unreserve_named and set_lock, extend_lock and remove_lock in the future?

[xlc]

fungibles traits are implemented

Current interface is not impacted.

[TorstenStueber]

fungibles traits are implemented

@xlc This issue is specifically about Fungibles::InspectFreeze, Fungibles::InspectHold, etc. (three more, see here).

To my knowledge they are not implemented yet.

[wischli]

I'd like to add that the fn reducible_balance impl of orml-tokens seems to diverge from frame (both for fungible, i.e. pallet-balances as well as fungibles, i.e. pallet-assets:

For orml-tokens, the only case considering subtracting ED from the liquid funds is Preservation::Protect whereas in frame this can also occur for other preservations with Preservation::Preserve being the most protected one:

orml-tokens

open-runtime-module-library/tokens/src/lib.rs

Line 1809 in 83a76c2

if frame_system::Pallet::<T>::can_dec_provider(who) && !matches!(preservation, Preservation::Protect) {

pallet-balances

https://github.com/paritytech/polkadot-sdk/blob/3ae86ae075ac5eb9b80f89f09bd7f4a63f97c582/substrate/frame/balances/src/impl_fungible.rs#L57-L67

pallet-assets

https://github.com/paritytech/polkadot-sdk/blob/3ae86ae075ac5eb9b80f89f09bd7f4a63f97c582/substrate/frame/assets/src/impl_fungibles.rs#L58-L59

[Chralt98]

@xlc

orml-currencies still uses the Currency traits here:

open-runtime-module-library/currencies/src/lib.rs

Line 43 in 9869331

Currency as PalletCurrency, ExistenceRequirement, Get, Imbalance, LockableCurrency as PalletLockableCurrency,

https://forum.polkadot.network/t/polkadot-release-analysis-v0-9-41-v0-9-42/2828#high-impact-7

paritytech/substrate#12951

From the Upgrading section:

It is not crucial to get this done in any particular timeframe, however at some point in the future Currency traits, Locks and Reserves will be deprecated and removed, so it will need to happen before then.

So, I assume since the traits haven't been removed yet, the implementations using the Currency traits in orml-currencies won't change?

[xlc]

the current code works fine so there is no plan to change it unless absolutely necessary