Add AssetDelta.__mul__ method

CHANGELOG.md

@@ -1,6 +1,6 @@
-# Current
+# 0.22.2
 
-- TODO
+- Add `AssetDelta.__mul__` method
 
 # 0.21.1
 

eth_defi/tx.py

@@ -97,6 +97,26 @@ def __post_init__(self):
         assert type(self.asset) in (HexAddress, str)
         assert self.raw_amount, "Raw amount should be specified"
 
+    def __mul__(self, other: float | int) -> "AssetDelta":
+        """Adjust asset delta by multiplier.
+
+        E.g. multiplied by 0.99 returns :py:class:`AssetDelta` with
+        raw amount reduced 1%. Uses integer flooring.
+
+        Example:
+
+        .. code-block:: python
+
+            d = AssetDelta(usdc.address, 1*10**6)
+            d2 = d * 0.99
+            assert d2.raw_amount == int(10**6 * 0.99)
+        """
+        assert isinstance(other, (float, int))
+        return AssetDelta(
+            self.asset,
+            int(self.raw_amount * other)
+        )
+
     def is_incoming(self) -> bool:
         """This delta describes incoming assets."""
         return self.raw_amount > 0

tests/enzyme/test_vault_controlled_wallet.py

@@ -92,6 +92,14 @@ def deployment(
     return deployment
 
 
+def test_asset_delta_mul(usdc: Contract):
+    """Check that the asset delta multiplier works."""
+
+    d = AssetDelta(usdc.address, 1*10**6)
+    d2 = d * 0.99
+    assert d2.raw_amount == int(10**6 * 0.99)
+
+
 def test_repr(
     web3: Web3,
     deployment: EnzymeDeployment,