Stanislav Angelovič
58358eefa1
This makes the library more robust and prone to user's errors when the user writes an extension for their custom type. In case they forget to implement a serialization function for that type and yet insert an object of that type into sdbus::Message, the current behavior is that, surprisingly, the library masks the error as it resolves the call to the Variant overload, because Variant provides an implicit template converting constructor, so the library tries to construct first the Variant object from the object of custom type, and then inserting into the message that Variant object. Variant constructor serializes the underlying object into its internal message object, which resolves to the same message insertion overload, creating an infinite recursion and ultimately the stack overflow. This is undesired and plain wrong. Marking this Variant converting constructor solves these problems, plus in overall it makes the code a little safer and more verbose. With explicit Variant constructor, when the user forgets to implement a serialization function for their type, the call of such function will fail with an expressive compilation error, and will produce no undesired, surprising results.
sdbus-c++
sdbus-c++ is a high-level C++ D-Bus library for Linux designed to provide expressive, easy-to-use API in modern C++. It adds another layer of abstraction on top of sd-bus, a nice, fresh C D-Bus implementation by systemd.
sdbus-c++ has been written primarily as a replacement of dbus-c++, which currently suffers from a number of (unresolved) bugs, concurrency issues and inherent design complexities and limitations. sdbus-c++ has learned from dbus-c++ and has chosen a different path, a path of simple yet powerful design that is intuitive and friendly to the user and inherently free of those bugs.
Even though sdbus-c++ uses sd-bus library, it is not necessarily constrained to systemd and can perfectly be used in non-systemd environments as well.
Building and installing the library
The library is built using CMake:
$ mkdir build
$ cd build
$ cmake .. -DCMAKE_BUILD_TYPE=Release ${OTHER_CONFIG_FLAGS}
$ cmake --build .
$ sudo cmake --build . --target install
CMake configuration flags for sdbus-c++
-
BUILD_CODE_GEN[boolean]Option for building the stub code generator
sdbus-c++-xml2cppfor generating the adaptor and proxy interfaces out of the D-Bus IDL XML description. Default value:OFF. Use-DBUILD_CODE_GEN=ONflag to turn on building the code gen. -
BUILD_DOC[boolean]Option for including sdbus-c++ documentation files and tutorials. Default value:
ON. With this option turned on, you may also enable/disable the following option:-
BUILD_DOXYGEN_DOC[boolean]Option for building Doxygen documentation of sdbus-c++ API. If enabled, the documentation must still be built explicitly through
cmake --build . --target doc. Default value:OFF. Use-DBUILD_DOXYGEN_DOC=OFFto disable searching for Doxygen and building Doxygen documentation of sdbus-c++ API.
-
-
BUILD_TESTS[boolean]Option for building sdbus-c++ unit and integration tests, invokable by
cmake --build . --target test(Note: before invokingcmake --build . --target test, make sure you copytests/integrationtests/files/org.sdbuscpp.integrationtests.conffile to/etc/dbus-1/system.ddirectory). That incorporates downloading and building static libraries of Google Test. Default value:OFF. Use-DBUILD_TESTS=ONto enable building the tests. With this option turned on, you may also enable/disable the following options:-
ENABLE_PERF_TESTS[boolean]Option for building sdbus-c++ performance tests. Default value:
OFF. -
ENABLE_STRESS_TESTS[boolean]Option for building sdbus-c++ stress tests. Default value:
OFF. -
INSTALL_TESTS[boolean]Option for installing tests that were built. Default value:
OFF. -
TESTS_INSTALL_PATH[string]Path where the test binaries shall get installed. Default value:
${CMAKE_INSTALL_PREFIX}/tests/sdbus-c++(previously:/opt/test/bin).
-
-
BUILD_LIBSYSTEMD[boolean]Option for building libsystemd dependency library automatically when sdbus-c++ is built, and making libsystemd an integral part of sdbus-c++ library. Default value:
OFF. Might be very helpful in non-systemd environments where libsystemd shared library is unavailable (see Solving libsystemd dependency for more information). With this option turned on, you may also provide the following configuration flag:-
LIBSYSTEMD_VERSION[string]Defines version of systemd to be downloaded, built and integrated into sdbus-c++. Default value:
242. -
LIBSYSTEMD_EXTRA_CONFIG_OPTS[string]Additional options to be passed as-is to the libsystemd build system (meson for systemd v242) in its configure step. Can be used for passing e.g. toolchain file path in case of cross builds. Default value: empty.
-
-
CMAKE_BUILD_TYPE[string]This is a CMake-builtin option. Set to
Releaseto build sdbus-c++ for production use. Set toDebugif you want to help further develop (and debug) the library :) -
BUILD_SHARED_LIBS[boolean]This is a global CMake flag, promoted in sdbus-c++ project to a CMake option. Use this to control whether sdbus-c++ is built as either a shared or static library. Default value:
ON. -
BUILD_EXAMPLES[boolean]Build example programs which are located in the example directory. Examples are not installed. Default value:
OFF
Dependencies
C++17- the library uses C++17 features.libsystemd/libelogind/basu- libraries containing sd-bus implementation that sdbus-c++ is written around. In case oflibsystemdandlibelogind, version >= 236 is needed. (In case you have a non-systemd environment, don't worry, see Solving libsystemd dependency for more information.)googletest- google unit testing framework, only necessary when building tests, will be downloaded and built automatically.pkgconfig- required for sdbus-c++ to be able to find some dependency packages.expat- necessary when building xml2cpp code generator (BUILD_CODE_GENoption is ON).
Licensing
The library is distributed under LGPLv2.1 license, with a specific exception for macro/template/inline code in library header files.
References/documentation
- Using sdbus-c++ - the main, comprehensive tutorial on sdbus-c++
- Systemd and dbus configuration
- D-Bus Specification
- sd-bus Overview
Contributing
Contributions that increase the library quality, functionality, or fix issues are very welcome. To introduce a change, please submit a pull request with a description.