feat(tokens): OnDeposit, OnTransfer, OnSlash hooks #815
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tokens/src/lib.rs
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| @@ -890,6 +901,7 @@ impl<T: Config> Pallet<T> { | |||
| amount: T::Balance, | |||
| existence_requirement: ExistenceRequirement, | |||
| ) -> DispatchResult { | |||
| T::OnTransfer::on_transfer(currency_id, from, to, amount)?; | |||
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move this after the early return. on the case no event is emitted, no hook should be called.
| } | ||
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| /// Hook to run before transferring from an account to another. | ||
| pub trait OnTransfer<AccountId, CurrencyId, Balance> { |
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Do you intent to allow OnTransfer to be able to cancel the transfer?
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Ideally I wanted all of these hooks to be able to fail, in consequence cancelling the transfer / deposit / slash. The trait bound on slash() prevents such an implementation unfortunately, but the other two (on_deposit and on_transfer) are allowed to return a Result so that's what they do.
Codecov Report
@@ Coverage Diff @@
## master #815 +/- ##
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+ Coverage 78.05% 78.24% +0.19%
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Files 102 102
Lines 10041 10129 +88
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+ Hits 7837 7925 +88
Misses 2204 2204
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Adds configurable hooks to the Tokens pallet, for functions which emit
Event::Deposited,Event::Transfer,Event::Slashed. A hook call is not added toslash_reserved_named(...), because that function callsslash_reserved(...)so the hook is run there.These hooks enable tokenizing "positions" which require lazy operations to be executed each time they are modified. An example would be tokenizing one's nomination / stake. For Alice to send her nominated position (the right to claim the nominated tokens) to Bob, her nomination rewards have to first be collected. In this example, the transfer hook would collect the sender's rewards before the actual transfer occurs.