Merge pull request #81 from nqminds/feat/add-LoggerContextManager

feat: add `LoggerContextManager` Python class

CHANGELOG.md

@@ -7,6 +7,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add `nqm.logger.LoggerContextManager` Python class, which automatically
+  creates/deletes a
+  [`nqm.logger.Logger`](https://nqminds.github.io/nqm-irimager/apidoc/nqm.irimager.html#nqm.irimager.Logger)
+  object when used in a [`with:` statement][PEP 343] ([#81][]).
+
+[#81]: https://github.com/nqminds/nqm-irimager/pull/81
+[PEP 343]: https://peps.python.org/pep-0343/
+
 ## [1.0.0] - 2023-10-30
 
 Initial release.

CMakeLists.txt

@@ -47,6 +47,7 @@ add_custom_command(
     "-I;$<JOIN:$<TARGET_PROPERTY:irimager,INCLUDE_DIRECTORIES>,;-I;>"
     -std=c++17
     "${CMAKE_CURRENT_SOURCE_DIR}/src/nqm/irimager/irimager_class.hpp"
+    "${CMAKE_CURRENT_SOURCE_DIR}/src/nqm/irimager/logger_context_manager.hpp"
     "${CMAKE_CURRENT_SOURCE_DIR}/src/nqm/irimager/logger.hpp"
   COMMAND_EXPAND_LISTS
   VERBATIM
@@ -165,6 +166,19 @@ target_link_libraries(logger
     irlogger_to_spd
 )
 
+add_library(logger_context_manager OBJECT
+  "src/nqm/irimager/logger_context_manager.cpp"
+)
+set_target_properties(logger_context_manager PROPERTIES
+  PRIVATE_HEADER
+    "src/nqm/irimager/logger_context_manager.hpp"
+  POSITION_INDEPENDENT_CODE ON # -fPIC
+)
+target_link_libraries(logger_context_manager
+  PUBLIC
+    logger
+)
+
 pybind11_add_module(irimager MODULE
   "src/nqm/irimager/irimager.cpp"
   "${CMAKE_CURRENT_BINARY_DIR}/docstrings.h"
@@ -180,6 +194,7 @@ target_link_libraries(irimager
     irimager_class
     irlogger_parser
     irlogger_to_spd
+    logger_context_manager
     logger
 )
 

README.md

@@ -71,16 +71,17 @@ easy as:
 ```python
 import datetime
 import logging
-from nqm.irimager import IRImager, Logger
+from nqm.irimager import IRImager, LoggerContextManager
 
 logging.basicConfig()
 logging.getLogger().setLevel(1) # trace
-logger = Logger()
+
 # Your XML config,
 # see http://documentation.evocortex.com/libirimager2/html/Overview.html#subsec_overview_config_file
 XML_CONFIG = "tests/__fixtures__/382x288@27Hz.xml"
-irimager = IRImager(XML_CONFIG)
-with irimager:
+with LoggerContextManager():
+  irimager = IRImager(XML_CONFIG)
+  with irimager:
     print(f"Started at {datetime.datetime.now()}")
     while True: # press CTRL+C to stop this program
         try:
@@ -90,8 +91,6 @@ with irimager:
           raise error
         frame_in_celsius = array / (10 ** irimager.get_temp_range_decimal()) - 100
         print(f"At {timestamp}: Average temperature is {frame_in_celsius.mean()}")
-
-del logger # to stop
 ```
 
 ## Development

src/nqm/irimager/__init__.pyi

@@ -101,3 +101,19 @@ class Logger:
     def __init__(self) -> None:
         """Creates a new logger using the default Python :py:class:`logging.Logger`"""
     def __del__(self): ...
+
+class LoggerContextManager:
+    """Context Manager around a Logger object.
+
+    Designed for use with Python's ``with`` syntax.
+    """
+
+    def __enter__(self) -> None:
+        """Starts the logger if it's not already started."""
+    def __exit__(
+        self,
+        exc_type: typing.Optional[typing.Type[BaseException]],
+        exc: typing.Optional[BaseException],
+        traceback: typing.Optional[types.TracebackType],
+    ) -> None:
+        """Stops the logger"""

src/nqm/irimager/irimager.cpp

@@ -8,6 +8,7 @@
 
 #include "./irimager_class.hpp"
 #include "./logger.hpp"
+#include "./logger_context_manager.hpp"
 
 #ifndef DOCSTRINGS_H
 #error DOCSTRINGS_H must be defined to the output of pybind11_mkdocs
@@ -76,4 +77,16 @@ to control these cameras.)";
 
   pybind11::class_<Logger>(m, "Logger", DOC(Logger))
       .def(pybind11::init<>(), DOC(Logger, Logger));
+
+  pybind11::class_<LoggerContextManager>(m, "LoggerContextManager",
+                                         DOC(LoggerContextManager))
+      .def(pybind11::init<>())
+      .def("__enter__", &LoggerContextManager::start)
+      .def("__exit__",
+           [](LoggerContextManager *logger_cm,
+              [[maybe_unused]] const std::optional<pybind11::type>,
+              [[maybe_unused]] const std::optional<pybind11::object>,
+              [[maybe_unused]] const std::optional<pybind11::object>) {
+             logger_cm->stop();
+           });
 }

src/nqm/irimager/logger_context_manager.cpp

@@ -0,0 +1,9 @@
+#include "./logger_context_manager.hpp"
+
+LoggerContextManager::~LoggerContextManager() = default;
+
+void LoggerContextManager::start() {
+  if (!logger_) logger_ = std::make_unique<Logger>();
+}
+
+void LoggerContextManager::stop() { logger_ = nullptr; }

src/nqm/irimager/logger_context_manager.hpp

@@ -0,0 +1,31 @@
+#ifndef NQM_IRIMAGER_LOGGER_CONTEXT_MANAGER
+#define NQM_IRIMAGER_LOGGER_CONTEXT_MANAGER
+
+#include <memory>
+
+#include <pybind11/pybind11.h>
+
+#include "./logger.hpp"
+
+/**
+ * Context Manager around a Logger object.
+ *
+ * Designed for use with Python's ``with`` syntax.
+ */
+class LoggerContextManager {
+ public:
+  virtual ~LoggerContextManager();
+
+  /**
+   * Starts the logger if it's not already started.
+   */
+  void start();
+
+  /** Stops the logger */
+  void stop();
+
+ private:
+  std::unique_ptr<Logger> logger_;
+};
+
+#endif /* NQM_IRIMAGER_LOGGER_CONTEXT_MANAGER */

tests/test_logger_context_manager.py

@@ -0,0 +1,41 @@
+"""Tests for nqm.irimager.Logging"""
+import logging
+
+import pytest
+
+from nqm.irimager import LoggerContextManager
+
+
+def test_logger_in_context_manager(caplog):
+    """We should be able to wrap logger in a context manager"""
+
+    with caplog.at_level(logging.DEBUG):
+        with LoggerContextManager():
+            assert "Redirecting spdlogs to a callback." in caplog.text
+
+        caplog.clear()
+
+        # creating a second logger should be fine after the first contextmanager
+        # closes
+        with LoggerContextManager():
+            assert "Redirecting spdlogs to a callback." in caplog.text
+
+
+def test_logger_in_context_manager_handles_exception(caplog):
+    """We should be able to wrap logger in a context manager and handle exceptions"""
+
+    with caplog.at_level(logging.DEBUG):
+        # creating a second logger should be fine, even if the first
+        # contextmanager broke due to an exception
+        with pytest.raises(
+            NotImplementedError,
+            match="Testing whether contextmanager cleans up after errors",
+        ):
+            with LoggerContextManager():
+                raise NotImplementedError(
+                    "Testing whether contextmanager cleans up after errors"
+                )
+
+        caplog.clear()
+        with LoggerContextManager():
+            assert "Redirecting spdlogs to a callback." in caplog.text