feat: block number getter + setter

brownie/network/multicall.py

@@ -39,11 +39,13 @@ def __repr__(self) -> str:
 
 
 class Multicall:
+    """Context manager for batching multiple calls to constant contract functions."""
+
     def __init__(
         self, address: str = None, block_identifier: Union[int, str, bytes] = None
     ) -> None:
         self.address = address
-        self.block_identifier = block_identifier or chain.height
+        self._block_identifier = block_identifier or chain.height
         self._pending_calls: List[Call] = []
         self._complete = True
 
@@ -55,21 +57,21 @@ def __init__(
             elif "cmd" in active_network:
                 if block_identifier is not None:
                     raise ContractNotFound(
-                        f"Must deploy Multicall2 before block {self.block_identifier}. "
+                        f"Must deploy Multicall2 before block {self._block_identifier}. "
                         "Use `Multicall2.deploy` classmethod to deploy an instance of Multicall2."
                     )
                 deployment = self.deploy({"from": accounts[0]})
                 self.address = deployment.address
-                self.block_identifier = deployment.tx.block_number  # type: ignore
+                self._block_identifier = deployment.tx.block_number  # type: ignore
             else:
                 # live network and no address
                 raise ContractNotFound("Must provide Multicall2 address as argument")
 
-        if not web3.eth.get_code(self.address, self.block_identifier):
+        if not web3.eth.get_code(self.address, self._block_identifier):
             # TODO: Handle deploying multicall in a test network without breaking the expected chain
             # For Geth client's we can use state override to have multicall at any arbitrary address
             raise ContractNotFound(
-                f"Multicall2 at `{self.address}` not available at block `{self.block_identifier}`"
+                f"Multicall2 at `{self.address}` not available at block `{self._block_identifier}`"
             )
 
         contract = Contract.from_abi("Multicall2", self.address, MULTICALL2_ABI)  # type: ignore
@@ -84,7 +86,7 @@ def _flush(self, future_result: Result = None) -> Any:
         results = self._contract.tryAggregate(
             False,
             [_call.calldata for _call in self._pending_calls],
-            block_identifier=self.block_identifier,
+            block_identifier=self._block_identifier,
         )
         if not self._complete:
             ContractCall.__call__.__code__ = getattr(ContractCall, "__proxy_call_code")
@@ -141,6 +143,19 @@ def __exit__(self, exc_type: Exception, exc_val: Any, exc_tb: TracebackType) ->
         self._complete = True
         ContractCall.__call__.__code__ = getattr(ContractCall, "__original_call_code")
 
+    @property
+    def block_number(self) -> Union[int, str, bytes]:
+        return self._block_identifier
+
+    @block_number.setter
+    def block_number(self, value: Union[int, str, bytes]) -> None:
+        self.flush()
+        if not web3.eth.get_code(self.address, self._block_identifier):
+            raise ContractNotFound(
+                f"Multicall2 at `{self.address}` not available at block `{value}`"
+            )
+        self._block_identifier = value
+
     @classmethod
     def deploy(cls, tx_params: Dict) -> Contract:
         project = compile_source(MULTICALL2_SOURCE)