Use bounded typevar to avoid casting .duplicate()

src/rp2/abstract_entry_set.py

@@ -14,7 +14,7 @@
 
 from copy import copy
 from datetime import date, datetime
-from typing import Dict, Iterable, Iterator, List, Optional, Set
+from typing import Dict, Iterable, Iterator, List, Optional, Set, TypeVar
 
 from rp2.abstract_entry import AbstractEntry
 from rp2.configuration import MAX_DATE, MIN_DATE, Configuration
@@ -24,6 +24,8 @@
 from rp2.out_transaction import OutTransaction
 from rp2.rp2_error import RP2TypeError, RP2ValueError
 
+T = TypeVar("T", bound="AbstractEntrySet")
+
 
 class AbstractEntrySet(Iterable[AbstractEntry]):
     def __init__(
@@ -49,9 +51,9 @@ def __init__(
         self._entry_to_parent: Dict[AbstractEntry, Optional[AbstractEntry]] = {}
         self.__is_sorted: bool = False
 
-    def duplicate(self, from_date: date = MIN_DATE, to_date: date = MAX_DATE) -> "AbstractEntrySet":
+    def duplicate(self: T, from_date: date = MIN_DATE, to_date: date = MAX_DATE) -> T:
         # pylint: disable=protected-access
-        result: AbstractEntrySet = copy(self)
+        result: T = copy(self)
         result._from_date = from_date
         result._to_date = to_date
         # Force sort to recompute fields that are affected by time filter

src/rp2/balance.py

@@ -15,10 +15,11 @@
 from dataclasses import dataclass
 from datetime import date, datetime
 from decimal import Decimal
-from typing import Callable, Dict, List, Optional, Union, cast
+from typing import Callable, Dict, List, Optional
 
 from prezzemolo.utility import to_string
 
+from rp2.abstract_entry import AbstractEntry
 from rp2.configuration import Configuration
 from rp2.in_transaction import InTransaction
 from rp2.input_data import InputData
@@ -118,11 +119,11 @@ def __init__(
         from_account: Account
         to_account: Account
 
-        in_transactions: List[InTransaction] = cast(List[InTransaction], list(self.__input_data.unfiltered_in_transaction_set))
-        intra_transactions: List[IntraTransaction] = cast(List[IntraTransaction], list(self.__input_data.unfiltered_intra_transaction_set))
-        out_transactions: List[OutTransaction] = cast(List[OutTransaction], list(self.__input_data.unfiltered_out_transaction_set))
+        in_transactions = list(self.__input_data.unfiltered_in_transaction_set)
+        intra_transactions = list(self.__input_data.unfiltered_intra_transaction_set)
+        out_transactions = list(self.__input_data.unfiltered_out_transaction_set)
 
-        transactions: List[Union[InTransaction, IntraTransaction, OutTransaction]] = in_transactions + intra_transactions + out_transactions
+        transactions = in_transactions + intra_transactions + out_transactions
         transactions = sorted(
             transactions,
             key=_transaction_time_sort_key,
@@ -244,5 +245,5 @@ def _balance_sort_key(balance: Balance) -> str:
     return f"{balance.exchange}_{balance.holder}"
 
 
-def _transaction_time_sort_key(transaction: Union[InTransaction, IntraTransaction, OutTransaction]) -> datetime:
+def _transaction_time_sort_key(transaction: AbstractEntry) -> datetime:
     return transaction.timestamp

src/rp2/computed_data.py

@@ -208,8 +208,8 @@ def __init__(
         TransactionSet.type_check("taxable_event_set", unfiltered_taxable_event_set, EntrySetType.MIXED, asset, True)
         GainLossSet.type_check("gain_loss_set", unfiltered_gain_loss_set)
 
-        self.__filtered_taxable_event_set: TransactionSet = cast(TransactionSet, unfiltered_taxable_event_set.duplicate(from_date=from_date, to_date=to_date))
-        self.__filtered_gain_loss_set: GainLossSet = cast(GainLossSet, unfiltered_gain_loss_set.duplicate(from_date=from_date, to_date=to_date))
+        self.__filtered_taxable_event_set: TransactionSet = unfiltered_taxable_event_set.duplicate(from_date=from_date, to_date=to_date)
+        self.__filtered_gain_loss_set: GainLossSet = unfiltered_gain_loss_set.duplicate(from_date=from_date, to_date=to_date)
 
         yearly_gain_loss_list: List[YearlyGainLoss] = self._create_yearly_gain_loss_list(unfiltered_gain_loss_set, to_date)
         LOGGER.debug("%s: Created yearly gain-loss list", input_data.asset)

src/rp2/input_data.py

@@ -13,7 +13,6 @@
 # limitations under the License.
 
 from datetime import date
-from typing import cast
 
 from rp2.configuration import MAX_DATE, MIN_DATE, Configuration
 from rp2.entry_types import EntrySetType
@@ -53,15 +52,9 @@ def __init__(
         if not isinstance(to_date, date):
             raise RP2TypeError("Parameter 'to_date' is not of type date")
 
-        self.__filtered_in_transaction_set: TransactionSet = cast(
-            TransactionSet, self.__unfiltered_in_transaction_set.duplicate(from_date=from_date, to_date=to_date)
-        )
-        self.__filtered_out_transaction_set: TransactionSet = cast(
-            TransactionSet, self.__unfiltered_out_transaction_set.duplicate(from_date=from_date, to_date=to_date)
-        )
-        self.__filtered_intra_transaction_set: TransactionSet = cast(
-            TransactionSet, self.__unfiltered_intra_transaction_set.duplicate(from_date=from_date, to_date=to_date)
-        )
+        self.__filtered_in_transaction_set: TransactionSet = self.__unfiltered_in_transaction_set.duplicate(from_date=from_date, to_date=to_date)
+        self.__filtered_out_transaction_set: TransactionSet = self.__unfiltered_out_transaction_set.duplicate(from_date=from_date, to_date=to_date)
+        self.__filtered_intra_transaction_set: TransactionSet = self.__unfiltered_intra_transaction_set.duplicate(from_date=from_date, to_date=to_date)
 
     @property
     def asset(self) -> str: