Accept memoryview in setter and getter type annotations (gijzelaerr#647)

The setter functions already worked with memoryview at runtime (using
direct struct.pack() slice assignment), but the type annotations only
accepted bytearray. This caused mypy errors when passing memoryview
objects from ctypes buffers.

- Add Buffer type alias (Union[bytearray, memoryview]) to setters and getters
- Update all function signatures to accept Buffer
- Fix .decode() calls in getters to use bytes() for memoryview compat
- Add 17 memoryview compatibility tests

Credit: LuTiFlekSSer for identifying the memoryview compatibility issue.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: gijzelaerr

snap7/util/db.py

@@ -635,7 +635,9 @@ def get_value(self, byte_index: Union[str, int], type_: str) -> ValueType:
                 return type_to_func[type_](bytearray_, byte_index)
         raise ValueError
 
-    def set_value(self, byte_index: Union[str, int], type_: str, value: Union[bool, str, float]) -> Optional[bytearray]:
+    def set_value(
+        self, byte_index: Union[str, int], type_: str, value: Union[bool, str, float]
+    ) -> Optional[Union[bytearray, memoryview]]:
         """Sets the value for a specific type in the specified byte index.
 
         Args:

snap7/util/getters.py

@@ -1,12 +1,16 @@
 import struct
 from datetime import timedelta, datetime, date
-from typing import NoReturn
+from typing import NoReturn, Union
 from logging import getLogger
 
+#: Buffer types accepted by getter functions.
+#: Both :class:`bytearray` and :class:`memoryview` are supported.
+Buffer = Union[bytearray, memoryview]
+
 logger = getLogger(__name__)
 
 
-def get_bool(bytearray_: bytearray, byte_index: int, bool_index: int) -> bool:
+def get_bool(bytearray_: Buffer, byte_index: int, bool_index: int) -> bool:
     """Get the boolean value from location in bytearray
 
     Args:
@@ -28,7 +32,7 @@ def get_bool(bytearray_: bytearray, byte_index: int, bool_index: int) -> bool:
     return current_value == index_value
 
 
-def get_byte(bytearray_: bytearray, byte_index: int) -> bytes:
+def get_byte(bytearray_: Buffer, byte_index: int) -> bytes:
     """Get byte value from bytearray.
 
     Notes:
@@ -48,7 +52,7 @@ def get_byte(bytearray_: bytearray, byte_index: int) -> bytes:
     return value
 
 
-def get_word(bytearray_: bytearray, byte_index: int) -> bytearray:
+def get_word(bytearray_: Buffer, byte_index: int) -> bytearray:
     """Get word value from bytearray.
 
     Notes:
@@ -73,7 +77,7 @@ def get_word(bytearray_: bytearray, byte_index: int) -> bytearray:
     return value
 
 
-def get_int(bytearray_: bytearray, byte_index: int) -> int:
+def get_int(bytearray_: Buffer, byte_index: int) -> int:
     """Get int value from bytearray.
 
     Notes:
@@ -98,7 +102,7 @@ def get_int(bytearray_: bytearray, byte_index: int) -> int:
     return value
 
 
-def get_uint(bytearray_: bytearray, byte_index: int) -> int:
+def get_uint(bytearray_: Buffer, byte_index: int) -> int:
     """Get unsigned int value from bytearray.
 
     Notes:
@@ -121,7 +125,7 @@ def get_uint(bytearray_: bytearray, byte_index: int) -> int:
     return int(get_word(bytearray_, byte_index))
 
 
-def get_real(bytearray_: bytearray, byte_index: int) -> float:
+def get_real(bytearray_: Buffer, byte_index: int) -> float:
     """Get real value.
 
     Notes:
@@ -145,7 +149,7 @@ def get_real(bytearray_: bytearray, byte_index: int) -> float:
     return real
 
 
-def get_fstring(bytearray_: bytearray, byte_index: int, max_length: int, remove_padding: bool = True) -> str:
+def get_fstring(bytearray_: Buffer, byte_index: int, max_length: int, remove_padding: bool = True) -> str:
     """Parse space-padded fixed-length string from bytearray
 
     Notes:
@@ -176,7 +180,7 @@ def get_fstring(bytearray_: bytearray, byte_index: int, max_length: int, remove_
         return string
 
 
-def get_string(bytearray_: bytearray, byte_index: int) -> str:
+def get_string(bytearray_: Buffer, byte_index: int) -> str:
     """Parse string from bytearray
 
     Notes:
@@ -210,7 +214,7 @@ def get_string(bytearray_: bytearray, byte_index: int) -> str:
     return "".join(data)
 
 
-def get_dword(bytearray_: bytearray, byte_index: int) -> int:
+def get_dword(bytearray_: Buffer, byte_index: int) -> int:
     """Gets the dword from the buffer.
 
     Notes:
@@ -235,7 +239,7 @@ def get_dword(bytearray_: bytearray, byte_index: int) -> int:
     return dword
 
 
-def get_dint(bytearray_: bytearray, byte_index: int) -> int:
+def get_dint(bytearray_: Buffer, byte_index: int) -> int:
     """Get dint value from bytearray.
 
     Notes:
@@ -262,7 +266,7 @@ def get_dint(bytearray_: bytearray, byte_index: int) -> int:
     return dint
 
 
-def get_udint(bytearray_: bytearray, byte_index: int) -> int:
+def get_udint(bytearray_: Buffer, byte_index: int) -> int:
     """Get unsigned dint value from bytearray.
 
     Notes:
@@ -289,7 +293,7 @@ def get_udint(bytearray_: bytearray, byte_index: int) -> int:
     return dint
 
 
-def get_s5time(bytearray_: bytearray, byte_index: int) -> str:
+def get_s5time(bytearray_: Buffer, byte_index: int) -> str:
     micro_to_milli = 1000
     data_bytearray = bytearray_[byte_index : byte_index + 2]
     s5time_data_int_like = list(data_bytearray.hex())
@@ -315,7 +319,7 @@ def get_s5time(bytearray_: bytearray, byte_index: int) -> str:
     return "".join(str(s5time))
 
 
-def get_dt(bytearray_: bytearray, byte_index: int) -> str:
+def get_dt(bytearray_: Buffer, byte_index: int) -> str:
     """Get  DATE_AND_TIME Value from bytearray as ISO 8601 formatted Date String
     Notes:
         Datatype `DATE_AND_TIME` consists in 8 bytes in the PLC.
@@ -331,7 +335,7 @@ def get_dt(bytearray_: bytearray, byte_index: int) -> str:
     return get_date_time_object(bytearray_, byte_index).isoformat(timespec="microseconds")
 
 
-def get_date_time_object(bytearray_: bytearray, byte_index: int) -> datetime:
+def get_date_time_object(bytearray_: Buffer, byte_index: int) -> datetime:
     """Get  DATE_AND_TIME Value from bytearray as python datetime object
     Notes:
         Datatype `DATE_AND_TIME` consists in 8 bytes in the PLC.
@@ -364,7 +368,7 @@ def bcd_to_byte(byte: int) -> int:
     return datetime(year, month, day, hour, min_, sec, microsec)
 
 
-def get_time(bytearray_: bytearray, byte_index: int) -> str:
+def get_time(bytearray_: Buffer, byte_index: int) -> str:
     """Get time value from bytearray.
 
     Notes:
@@ -408,7 +412,7 @@ def get_time(bytearray_: bytearray, byte_index: int) -> str:
     return time_str
 
 
-def get_usint(bytearray_: bytearray, byte_index: int) -> int:
+def get_usint(bytearray_: Buffer, byte_index: int) -> int:
     """Get the unsigned small int from the bytearray
 
     Notes:
@@ -434,7 +438,7 @@ def get_usint(bytearray_: bytearray, byte_index: int) -> int:
     return value
 
 
-def get_sint(bytearray_: bytearray, byte_index: int) -> int:
+def get_sint(bytearray_: Buffer, byte_index: int) -> int:
     """Get the small int
 
     Notes:
@@ -460,7 +464,7 @@ def get_sint(bytearray_: bytearray, byte_index: int) -> int:
     return value
 
 
-def get_lint(bytearray_: bytearray, byte_index: int) -> int:
+def get_lint(bytearray_: Buffer, byte_index: int) -> int:
     """Get the long int
 
     THIS VALUE IS NEITHER TESTED NOR VERIFIED BY A REAL PLC AT THE MOMENT
@@ -490,7 +494,7 @@ def get_lint(bytearray_: bytearray, byte_index: int) -> int:
     return int(lint)
 
 
-def get_lreal(bytearray_: bytearray, byte_index: int) -> float:
+def get_lreal(bytearray_: Buffer, byte_index: int) -> float:
     """Get the long real
 
     Datatype `lreal` (long real) consists in 8 bytes in the PLC.
@@ -515,7 +519,7 @@ def get_lreal(bytearray_: bytearray, byte_index: int) -> float:
     return float(struct.unpack_from(">d", bytearray_, offset=byte_index)[0])
 
 
-def get_lword(bytearray_: bytearray, byte_index: int) -> int:
+def get_lword(bytearray_: Buffer, byte_index: int) -> int:
     """Get the long word
 
     Notes:
@@ -540,7 +544,7 @@ def get_lword(bytearray_: bytearray, byte_index: int) -> int:
     return lword
 
 
-def get_ulint(bytearray_: bytearray, byte_index: int) -> int:
+def get_ulint(bytearray_: Buffer, byte_index: int) -> int:
     """Get ulint value from bytearray.
 
     Notes:
@@ -565,7 +569,7 @@ def get_ulint(bytearray_: bytearray, byte_index: int) -> int:
     return lint
 
 
-def get_tod(bytearray_: bytearray, byte_index: int) -> timedelta:
+def get_tod(bytearray_: Buffer, byte_index: int) -> timedelta:
     len_bytearray_ = len(bytearray_)
     byte_range = byte_index + 4
     if len_bytearray_ < byte_range:
@@ -576,7 +580,7 @@ def get_tod(bytearray_: bytearray, byte_index: int) -> timedelta:
     return time_val
 
 
-def get_date(bytearray_: bytearray, byte_index: int = 0) -> date:
+def get_date(bytearray_: Buffer, byte_index: int = 0) -> date:
     len_bytearray_ = len(bytearray_)
     byte_range = byte_index + 2
     if len_bytearray_ < byte_range:
@@ -587,7 +591,7 @@ def get_date(bytearray_: bytearray, byte_index: int = 0) -> date:
     return date_val
 
 
-def get_ltime(bytearray_: bytearray, byte_index: int) -> timedelta:
+def get_ltime(bytearray_: Buffer, byte_index: int) -> timedelta:
     """Get LTIME value from bytearray.
 
     Notes:
@@ -612,7 +616,7 @@ def get_ltime(bytearray_: bytearray, byte_index: int) -> timedelta:
     return timedelta(microseconds=nanoseconds // 1000)
 
 
-def get_ltod(bytearray_: bytearray, byte_index: int) -> timedelta:
+def get_ltod(bytearray_: Buffer, byte_index: int) -> timedelta:
     """Get LTOD (Long Time of Day) value from bytearray.
 
     Notes:
@@ -635,7 +639,7 @@ def get_ltod(bytearray_: bytearray, byte_index: int) -> timedelta:
     return result
 
 
-def get_ldt(bytearray_: bytearray, byte_index: int) -> datetime:
+def get_ldt(bytearray_: Buffer, byte_index: int) -> datetime:
     """Get LDT (Long Date and Time) value from bytearray.
 
     Notes:
@@ -655,7 +659,7 @@ def get_ldt(bytearray_: bytearray, byte_index: int) -> datetime:
     return epoch + timedelta(microseconds=nanoseconds // 1000)
 
 
-def get_dtl(bytearray_: bytearray, byte_index: int) -> datetime:
+def get_dtl(bytearray_: Buffer, byte_index: int) -> datetime:
     time_to_datetime = datetime(
         year=int.from_bytes(bytearray_[byte_index : byte_index + 2], byteorder="big"),
         month=int(bytearray_[byte_index + 2]),
@@ -670,7 +674,7 @@ def get_dtl(bytearray_: bytearray, byte_index: int) -> datetime:
     return time_to_datetime
 
 
-def get_char(bytearray_: bytearray, byte_index: int) -> str:
+def get_char(bytearray_: Buffer, byte_index: int) -> str:
     """Get char value from bytearray.
 
     Notes:
@@ -694,7 +698,7 @@ def get_char(bytearray_: bytearray, byte_index: int) -> str:
     return char
 
 
-def get_wchar(bytearray_: bytearray, byte_index: int) -> str:
+def get_wchar(bytearray_: Buffer, byte_index: int) -> str:
     """Get wchar value from bytearray.
 
     Datatype `wchar` in the PLC is represented in 2 bytes. It has to be in utf-16-be format.
@@ -715,10 +719,10 @@ def get_wchar(bytearray_: bytearray, byte_index: int) -> str:
     """
     if bytearray_[byte_index] == 0:
         return chr(bytearray_[byte_index + 1])
-    return bytearray_[byte_index : byte_index + 2].decode("utf-16-be")
+    return bytes(bytearray_[byte_index : byte_index + 2]).decode("utf-16-be")
 
 
-def get_wstring(bytearray_: bytearray, byte_index: int) -> str:
+def get_wstring(bytearray_: Buffer, byte_index: int) -> str:
     """Parse wstring from bytearray
 
     Notes:
@@ -759,8 +763,8 @@ def get_wstring(bytearray_: bytearray, byte_index: int) -> str:
             f"expected or is larger than 16382. Bytearray doesn't seem to be a valid string."
         )
 
-    return bytearray_[wstring_start : wstring_start + wstr_symbols_amount].decode("utf-16-be")
+    return bytes(bytearray_[wstring_start : wstring_start + wstr_symbols_amount]).decode("utf-16-be")
 
 
-def get_array(bytearray_: bytearray, byte_index: int) -> NoReturn:
+def get_array(bytearray_: Buffer, byte_index: int) -> NoReturn:
     raise NotImplementedError