pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "dopt-basics"
-version = "0.1.3"
+version = "0.1.4dev1"
 description = "basic cross-project tools for Python-based d-opt projects"
 authors = [
     {name = "Florian Förster", email = "f.foerster@d-opt.com"},
@@ -69,7 +69,7 @@ directory = "reports/coverage"
 
 
 [tool.bumpversion]
-current_version = "0.1.3"
+current_version = "0.1.4dev1"
 parse = """(?x)
     (?P<major>0|[1-9]\\d*)\\.
     (?P<minor>0|[1-9]\\d*)\\.

scripts/bump_patch.ps1

@@ -0,0 +1,2 @@
+pdm run bump-my-version bump patch
+pdm run bump-my-version show current_version

src/dopt_basics/result_pattern.py

@@ -0,0 +1,201 @@
+from __future__ import annotations
+
+import dataclasses as dc
+import inspect
+import typing as t
+from collections.abc import Callable
+from functools import wraps
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from logging import Logger
+
+P = t.ParamSpec("P")
+T = t.TypeVar("T")
+
+
+# ** Exceptions for result wrappers
+class WrapperAccessResultDespiteError(Exception):
+    """wrapped results exception: raised if result is accessed, even though
+    there was an error in the underlying procedure"""
+
+
+@dc.dataclass(kw_only=True, slots=True)
+class Status:
+    code: int
+    description: str
+    message: str
+    ExceptionType: type[Exception] | None = None
+
+
+class StatusHandler:
+    __slots__ = ("logger", "_SUCCESS")
+
+    def __init__(
+        self,
+        logger: Logger | None = None,
+    ) -> None:
+        self.logger = logger
+
+        self._SUCCESS: t.Final[Status] = Status(
+            code=0, description="SUCCESS", message="operation executed successfully"
+        )
+
+    @property
+    def SUCCESS(self) -> Status:
+        return self._SUCCESS
+
+    def error_to_exception(
+        self,
+        error_state: Status,
+    ) -> Exception:
+        if error_state.ExceptionType is None:
+            raise ValueError(
+                "Cannot construct exception from state where no exception is defined"
+            )
+        return error_state.ExceptionType(error_state.message)
+
+    def exception_to_error(
+        self,
+        exception: Exception,
+        code: int,
+    ) -> Status:
+        doc_string = inspect.getdoc(exception)
+        description = doc_string if doc_string is not None else ""
+        message = str(exception)
+        return self.error_state(
+            code,
+            description,
+            message,
+            exception=exception,
+        )
+
+    @staticmethod
+    def error_state(
+        code: int,
+        description: str,
+        message: str,
+        exception: Exception | None,
+    ) -> Status:
+        if code == 0:
+            raise ValueError(
+                "Custom error codes must not be zero since this value "
+                "is reserved for successful operations"
+            )
+        elif code < 0:
+            raise ValueError("Custom error codes must not be smaller than zero")
+
+        exception_type: type[Exception] | None = None
+        if exception is not None:
+            exception_type = type(exception)
+
+        return Status(
+            code=code,
+            description=description,
+            message=message,
+            ExceptionType=exception_type,
+        )
+
+    def raise_for_status(
+        self,
+        state: Status,
+    ) -> None:
+        if state == self.SUCCESS:
+            if self.logger is not None:
+                self.logger.info(
+                    "[STATUS] Raise for status - SUCCESS. all good.", stack_info=True
+                )
+            return
+
+        exc = self.error_to_exception(error_state=state)
+        raise exc
+
+
+class NotSet:
+    __slots__ = tuple()
+
+    def __init__(self) -> None: ...
+
+    def __str__(self) -> str:
+        return ">Not set<"
+
+    def __repr__(self) -> str:
+        return f"{self.__class__.__name__}()"
+
+
+STATUS_HANDLER: t.Final[StatusHandler] = StatusHandler()
+
+
+class ResultWrapper(t.Generic[T]):
+    __slots__ = ("_result", "status")
+
+    def __init__(
+        self,
+        result: T | NotSet,
+        exception: Exception | None,
+        code_on_error: int,
+    ) -> None:
+        if isinstance(result, NotSet) and exception is None:
+            raise ValueError("[ResultWrapper] Set >NotSet< without exception")
+        elif not isinstance(result, NotSet) and exception is not None:
+            raise ValueError("[ResultWrapper] Set result with exception")
+
+        self._result = result
+        status: Status = STATUS_HANDLER.SUCCESS
+        if exception is not None:
+            status = STATUS_HANDLER.exception_to_error(exception, code=code_on_error)
+        self.status = status
+
+    @property
+    def result(self) -> T:
+        if isinstance(self._result, NotSet):
+            raise WrapperAccessResultDespiteError(
+                "Can not access result because it is not set"
+            )
+        return self._result
+
+    def __str__(self) -> str:
+        return f"Status(result: {self._result}, status: {self.status})"
+
+    def __repr__(self) -> str:
+        return self.__str__()
+
+    def unwrap(self) -> T:
+        STATUS_HANDLER.raise_for_status(self.status)
+
+        return self.result
+
+
+def wrap_result(
+    code_on_error: int,
+    logger: Logger | None = None,
+) -> Callable[[Callable[P, T]], Callable[P, ResultWrapper[T]]]:
+    def wrap_result(func: Callable[P, T]) -> Callable[P, ResultWrapper[T]]:
+        @wraps(func)
+        def wrapper(*args: P.args, **kwargs: P.kwargs) -> ResultWrapper[T]:
+            wrapped_result: ResultWrapper[T]
+            try:
+                res = func(*args, **kwargs)
+                wrapped_result = ResultWrapper(
+                    result=res, exception=None, code_on_error=code_on_error
+                )
+            except Exception as err:
+                wrapped_result = ResultWrapper(
+                    result=NotSet(), exception=err, code_on_error=code_on_error
+                )
+                if logger is not None:
+                    logger.info(
+                        (
+                            "[RESULT-WRAPPER] An exception in routine %s occurred - msg: %s, "
+                            "stack trace:"
+                        ),
+                        func.__name__,
+                        str(err),
+                        stack_info=True,
+                    )
+
+            return wrapped_result
+
+        return wrapper
+
+    return wrap_result

tests/test_result_pattern.py

@@ -0,0 +1,268 @@
+import logging
+
+import pytest
+
+from dopt_basics import result_pattern
+
+
+@pytest.fixture(scope="module")
+def status_hdlr() -> result_pattern.StatusHandler:
+    return result_pattern.StatusHandler()
+
+
+@pytest.fixture(scope="module")
+def dummy_logger() -> logging.Logger:
+    logger = logging.getLogger("test")
+    handlers = tuple(logger.handlers)
+    for handler in handlers:
+        logger.removeHandler(handler)
+    logger.addHandler(logging.NullHandler())
+
+    return logger
+
+
+def test_NotSet():
+    not_set = result_pattern.NotSet()
+    # using slots, dynamic attribute generation should not be possible
+    with pytest.raises(AttributeError):
+        not_set.test = "try to set value"  # type: ignore
+
+
+def test_status_handler_properties(status_hdlr, dummy_logger):
+    assert status_hdlr.logger is None
+    assert status_hdlr._SUCCESS is not None
+    assert status_hdlr.SUCCESS is not None
+    assert isinstance(status_hdlr.SUCCESS, result_pattern.Status)
+    assert status_hdlr.SUCCESS.code == 0
+    assert status_hdlr.SUCCESS.description == "SUCCESS"
+    status_hdlr.logger = dummy_logger
+    assert status_hdlr.logger is not None
+
+
+def test_status_handler_error_state_generation_FailCodeZero(status_hdlr):
+    description: str = "test"
+    message: str = "this is a test case"
+    code: int = 0
+    with pytest.raises(ValueError, match="must not be zero since this value"):
+        status_hdlr.error_state(code, description, message, None)
+
+
+def test_status_handler_error_state_generation_FailCodeNegative(status_hdlr):
+    description: str = "test"
+    message: str = "this is a test case"
+    code: int = -100
+    with pytest.raises(ValueError, match="must not be smaller than zero"):
+        status_hdlr.error_state(code, description, message, None)
+
+
+def test_status_handler_error_state_generation_SuccessWithoutException(status_hdlr):
+    description: str = "test"
+    message: str = "this is a test case"
+    code: int = 100
+    err_state = status_hdlr.error_state(code, description, message, None)
+    assert err_state.code == code
+    assert err_state.description == description
+    assert err_state.message == message
+    assert err_state.ExceptionType is None
+
+
+def test_status_handler_error_state_generation_SuccessWithException(status_hdlr):
+    description: str = "test"
+    message: str = "this is a test case"
+    code: int = 100
+    exception: Exception = ValueError(message)
+    err_state = status_hdlr.error_state(code, description, message, exception)
+    assert err_state.code == code
+    assert err_state.description == description
+    assert err_state.message == message
+    assert err_state.ExceptionType is ValueError
+
+
+def test_status_handler_error_to_exception_FailWithoutException(status_hdlr):
+    description: str = "test"
+    message: str = "this is a test case"
+    code: int = 100
+    err_state = status_hdlr.error_state(code, description, message, None)
+    assert err_state.code == code
+    assert err_state.description == description
+    assert err_state.message == message
+    assert err_state.ExceptionType is None
+    with pytest.raises(ValueError, match="state where no exception is defined"):
+        status_hdlr.error_to_exception(err_state)
+
+
+def test_status_handler_error_to_exception_SuccessWithException(status_hdlr):
+    description: str = "test"
+    message: str = "this is a test case"
+    code: int = 100
+    exception: Exception = ValueError(message)
+    err_state = status_hdlr.error_state(code, description, message, exception)
+    assert err_state.code == code
+    assert err_state.description == description
+    assert err_state.message == message
+    assert err_state.ExceptionType is ValueError
+    exc = status_hdlr.error_to_exception(err_state)
+    assert isinstance(exc, ValueError)
+    assert str(exc) == message
+
+
+def test_status_handler_exception_to_error_Success(status_hdlr):
+    description: str = "test"
+    message: str = "this is a test case"
+    code: int = 100
+
+    class TestException(Exception):
+        """test"""
+
+    exc = TestException(message)
+    err_state = status_hdlr.exception_to_error(exc, code)
+    assert err_state.code == code
+    assert err_state.description == description
+    assert err_state.message == message
+    assert err_state.ExceptionType is TestException
+
+
+def test_status_handler_raise_for_status_Success(dummy_logger):
+    status_hdlr = result_pattern.StatusHandler(dummy_logger)
+    state = status_hdlr.SUCCESS
+
+    assert status_hdlr.raise_for_status(state) is None
+
+
+def test_status_handler_raise_for_status_RaiseException(dummy_logger):
+    status_hdlr = result_pattern.StatusHandler(dummy_logger)
+
+    description: str = "test"
+    message: str = "this is a test case"
+    code: int = 100
+    exception: Exception = ValueError(message)
+    err_state = result_pattern.Status(
+        code=code, description=description, message=message, ExceptionType=type(exception)
+    )
+
+    with pytest.raises(type(exception), match=message):
+        status_hdlr.raise_for_status(err_state)
+
+
+def test_result_wrapper_class_FailInitNotSetNoException():
+    error_code = 146
+    test_result = result_pattern.NotSet()
+    exception = None
+
+    with pytest.raises(ValueError, match="Set >NotSet< without exception"):
+        _: result_pattern.ResultWrapper[int] = result_pattern.ResultWrapper(
+            result=test_result,
+            exception=exception,
+            code_on_error=error_code,
+        )
+
+
+def test_result_wrapper_class_FailInitSetResultWithException():
+    error_code = 146
+    test_result = 10
+    message = "Test of error message"
+    exception = ValueError(message)
+
+    with pytest.raises(ValueError, match="Set result with exception"):
+        _: result_pattern.ResultWrapper[int] = result_pattern.ResultWrapper(
+            result=test_result,
+            exception=exception,
+            code_on_error=error_code,
+        )
+
+
+def test_result_wrapper_class_Success(status_hdlr):
+    # successful operation
+    test_result = 10
+    error_code = 146
+    twrapper: result_pattern.ResultWrapper[int] = result_pattern.ResultWrapper(
+        result=test_result,
+        exception=None,
+        code_on_error=error_code,
+    )
+    assert twrapper.status == status_hdlr.SUCCESS
+    assert twrapper.result == test_result
+    assert twrapper.unwrap() == test_result
+    assert twrapper.status.code != error_code
+    assert twrapper.status.code == status_hdlr.SUCCESS.code
+
+
+def test_result_wrapper_class_FailureAccess(status_hdlr):
+    # test for no result
+    error_code = 146
+    test_result = result_pattern.NotSet()
+    message = "Test of error message"
+    exception = ValueError(message)
+    twrapper: result_pattern.ResultWrapper[int] = result_pattern.ResultWrapper(
+        result=test_result,
+        exception=exception,
+        code_on_error=error_code,
+    )
+    assert twrapper.status != status_hdlr.SUCCESS
+    assert twrapper.status.code == error_code
+    with pytest.raises(result_pattern.WrapperAccessResultDespiteError):
+        twrapper.result
+    with pytest.raises(type(exception), match=message):
+        _ = twrapper.unwrap()
+
+
+def test_wrap_result_ExceptionRaised():
+    MESSAGE = "Test case wrapped function decorator"
+    error_code = 103
+
+    @result_pattern.wrap_result(error_code)
+    def test_func_1() -> None:
+        raise ValueError(MESSAGE)
+
+    res = test_func_1()
+    assert isinstance(res, result_pattern.ResultWrapper)
+    assert res.status.code == error_code
+    assert res.status.message == MESSAGE
+    assert res.status.ExceptionType is ValueError
+    with pytest.raises(ValueError, match=MESSAGE):
+        res.unwrap()
+
+
+def test_wrap_result_NotNone_Success(status_hdlr):
+    error_code = 103
+
+    @result_pattern.wrap_result(error_code)
+    def test_func_2(x: str, y: str) -> int:
+        return int(int(x) / int(y))
+
+    res = test_func_2("2", "1")
+    assert res.result == 2
+    assert res.unwrap() == 2
+    assert res.status == status_hdlr.SUCCESS
+
+
+def test_wrap_result_NotNone_FailureZeroDivisionError():
+    error_code = 103
+
+    @result_pattern.wrap_result(error_code)
+    def test_func_2(x: str, y: str) -> int:
+        return int(int(x) / int(y))
+
+    res = test_func_2("2", "0")
+    with pytest.raises(result_pattern.WrapperAccessResultDespiteError):
+        res.result
+    with pytest.raises(ZeroDivisionError):
+        res.unwrap()
+    assert res.status.code == error_code
+    assert res.status.ExceptionType is ZeroDivisionError
+
+
+def test_wrap_result_NotNone_FailureValueErrorWithLogger(dummy_logger):
+    error_code = 103
+
+    @result_pattern.wrap_result(error_code, logger=dummy_logger)
+    def test_func_2(x: str, y: str) -> int:
+        return int(int(x) / int(y))
+
+    res = test_func_2("2", "test")
+    with pytest.raises(result_pattern.WrapperAccessResultDespiteError):
+        res.result
+    with pytest.raises(ValueError):
+        res.unwrap()
+    assert res.status.code == error_code
+    assert res.status.ExceptionType is ValueError