feat(nano): implement lazy imports

hathor/conf/settings.py

@@ -31,7 +31,7 @@
 GENESIS_TOKEN_UNITS = 1 * (10**9)  # 1B
 GENESIS_TOKENS = GENESIS_TOKEN_UNITS * (10**DECIMAL_PLACES)  # 100B
 
-HATHOR_TOKEN_UID = b'\x00'
+HATHOR_TOKEN_UID: bytes = b'\x00'
 
 
 @unique
@@ -469,7 +469,7 @@ def GENESIS_TX2_TIMESTAMP(self) -> int:
     ENABLE_NANO_CONTRACTS: NanoContractsSetting = NanoContractsSetting.DISABLED
 
     # List of enabled blueprints.
-    BLUEPRINTS: dict[bytes, 'str'] = {}
+    BLUEPRINTS: dict[bytes, str] = {}
 
     # The consensus algorithm protocol settings.
     CONSENSUS_ALGORITHM: ConsensusSettings = PowSettings()

hathor/dag_builder/artifacts.py

@@ -14,7 +14,7 @@
 
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Iterator, NamedTuple, TypeVar
+from typing import TYPE_CHECKING, Iterator, NamedTuple, Sequence, TypeVar
 
 from hathor.dag_builder.types import DAGNode
 from hathor.manager import HathorManager
@@ -49,9 +49,9 @@ def get_typed_vertex(self, name: str, type_: type[T]) -> T:
         assert isinstance(vertex, type_)
         return vertex
 
-    def get_typed_vertices(self, names: list[str], type_: type[T]) -> list[T]:
+    def get_typed_vertices(self, names: Sequence[str], type_: type[T]) -> Sequence[T]:
         """Get a list of vertices by name, asserting they are of the provided type."""
-        return [self.get_typed_vertex(name, type_) for name in names]
+        return tuple(self.get_typed_vertex(name, type_) for name in names)
 
     def propagate_with(self, manager: HathorManager, *, up_to: str | None = None) -> None:
         """

hathor/nanocontracts/__init__.py

@@ -12,16 +12,20 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from hathor.conf import settings
 from hathor.nanocontracts.blueprint import Blueprint
 from hathor.nanocontracts.context import Context
+from hathor.nanocontracts.contract_accessor import get_contract
 from hathor.nanocontracts.exception import NCFail
 from hathor.nanocontracts.on_chain_blueprint import OnChainBlueprint
 from hathor.nanocontracts.runner import Runner
 from hathor.nanocontracts.storage import NCMemoryStorageFactory, NCRocksDBStorageFactory, NCStorageFactory
-from hathor.nanocontracts.types import fallback, public, view
+from hathor.nanocontracts.types import TokenUid, VertexId, fallback, public, view
 
 # Identifier used in metadata's voided_by when a Nano Contract method fails.
 NC_EXECUTION_FAIL_ID: bytes = b'nc-fail'
+HATHOR_TOKEN_UID: TokenUid = TokenUid(VertexId(settings.HATHOR_TOKEN_UID))
+
 
 __all__ = [
     'Blueprint',
@@ -36,4 +40,6 @@
     'fallback',
     'view',
     'NC_EXECUTION_FAIL_ID',
+    'HATHOR_TOKEN_UID',
+    'get_contract',
 ]

hathor/nanocontracts/allowed_imports.py

@@ -33,7 +33,11 @@
     ),
     'collections': dict(OrderedDict=collections.OrderedDict),
     # hathor
-    'hathor.nanocontracts': dict(Blueprint=nc.Blueprint),
+    'hathor.nanocontracts': dict(
+        Blueprint=nc.Blueprint,
+        HATHOR_TOKEN_UID=nc.HATHOR_TOKEN_UID,
+        get_contract=nc.contract_accessor.get_contract,
+    ),
     'hathor.nanocontracts.blueprint': dict(Blueprint=nc.Blueprint),
     'hathor.nanocontracts.context': dict(Context=nc.Context),
     'hathor.nanocontracts.exception': dict(NCFail=nc.NCFail),

hathor/nanocontracts/blueprint_env.py

@@ -171,7 +171,14 @@ def call_public_method(
         **kwargs: Any,
     ) -> Any:
         """Call a public method of another contract."""
-        return self.__runner.syscall_call_another_contract_public_method(nc_id, method_name, actions, args, kwargs)
+        return self.__runner.syscall_call_another_contract_public_method(
+            nc_id,
+            method_name,
+            actions,
+            args,
+            kwargs,
+            forbid_fallback=False,
+        )
 
     @final
     def proxy_call_public_method(