GNU uCommon C++

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Contents

distributed as:ucommon
external links:GNU uCommon C++
license used:GNU L-GPL 3.0
required by:GNU SIP Witch GNU ccAudio2 GNU ccScript
related to:

Description

GNU uCommon C++ is meant as a very light-weight C++ library to facilitate using C++ design patterns even for very deeply embedded applications, such as for systems using uclibc along with posix threading support. For this reason, GNU uCommon C++ disables language features that consume memory or introduce runtime overhead, such as rtti and exception handling, and assumes one will mostly be linking applications with other pure C based libraries rather than using the overhead of the standard C++ library and other similar class frameworks.

GNU uCommon C++ introduces some Objective-C based design patterns, such as reference counted objects, memory pools, smart pointers, and offers dynamic typing through very light use of inline templates for pure type translation that are then tied to concrete base classes to avoid template instantiation issues. C++ auto-variable automation is also used to enable referenced objects to be deleted and threading locks to be released that are acquired automatically when methods return rather than requiring one to explicitly code for these things.

GNU uCommon C++ depends on and when necessary will introduce some portable C replacement functions, especially for sockets, such as adding getaddrinfo for platforms which do not have it, or when threadsafe versions of existing C library functions are needed. Basic socket support for connecting to named destinations and multicast addresses, and binding to interfaces with IPV4 and IPV6 addresses is directly supported. Support for high resolution timing and Posix realtime clocks are also used when available.

While GNU uCommon C++ has been influenced by GNU Common C++, it introduces some new concepts for handling of thread locking and synchronization. GNU uCommon C++ also builds all higher level thread synchronization objects directly from conditionals. Hence, on platforms which for example do not have rwlocks, barriers, or semaphores, these are still found in GNU uCommon C++. A common and consistent call methodology is used for all locks, whether mutex, rw, or semaphore, based on whether used for exclusive or "shared" locking.

GNU uCommon C++ requires some knowledge of compiler switches and options to disable language features, the C++ runtime and stdlibs, and associated C++ headers. The current version supports compiling with GCC, which is commonly found on GNU/Linux, OS/X, BSD based systems, and many other platforms; and the Sun Workshop compiler, which is offered as an example how to adapt GNU uCommon C++ for additional compilers. GNU uCommon C++ may also be built with GCC cross compiling for mingw32 for Microsoft Windows targets using the Redhat w32 pthread library.

The minimum platform support for GNU uCommon C++ is a modern and working posix pthread threading library. GNU uCommon C++ does not support other non-posix threading models such as Microsoft Windows threads or non-preemtive threading libraries like GNU pth, so that we could optimize development efforts around Posix pthread exclusively. I further use a subset of posix threads to assure wider portability by avoiding more specialized features like process shared synchronization objects, pthread rwlocks and pthread semaphores, as these are not implemented on all platforms that I have found.

The first three releases of GNU uCommon C++ were introduced in 1999-2000 as a pure "C" library for embedded targets, and had not seen an update in 7 years. Hence I have had the package name in use for a very long time. Work on what became GNU uCommon C++ 0.4 was originally intended as a refactoring effort for GNU Common C++ to better support IPV6, and became something different as entirely new code was written in 2006. I originally hoped to release GNU uCommon C++ in March of 2007 as a new package under the GNU GPL V3, but the license was unavoidably delayed. I may use GNU uCommon C++ to offer guidelines and code for further improving GNU Common C++ releases, I may merge the two packages, or I may make GNU Common C++ an extension library for GNU uCommon C++. This has not been decided yet.

Development

Current goals are in clarifying object naming and the current ABI.

Documentation

Full class documentation is online.

Downloading

All releases of the ucommon package are found at ftp.gnu.org.

Related

GNU uCommon C++ is still related to GNU Common C++.

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