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GNU Info File | 1994-11-07 | 40.1 KB | 823 lines

This is Info file libg++.info, produced by Makeinfo-1.55 from the input file ./libg++.texi. START-INFO-DIR-ENTRY * Libg++: (libg++). The g++ class library. END-INFO-DIR-ENTRY This file documents the features and implementation of The GNU C++ library Copyright (C) 1988, 1991, 1992 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the section entitled "GNU Library General Public License" is included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the section entitled "GNU Library General Public License" and this permission notice may be included in translations approved by the Free Software Foundation instead of in the original English.  File: libg++.info, Node: Top, Next: Copying, Up: (DIR) Introduction ************ This manual documents how to install and use the GNU C++ library. * Menu: * Copying:: GNU Library Public License says how you can copy and share the GNU C++ library. * Contributors:: People who have contributed to GNU C++ library. * Installation:: How to configure, compile and install GNU C++ library * Trouble:: If you have trouble installing GNU C++ library. * General:: Aims, objectives, and limitations of the GNU C++ library * Conventions:: Stylistic conventions * OK:: Support for representation invariants * Proto:: Introduction to container class prototypes * Pix:: Pseudo-indexes * Representations:: How variable-sized objects are represented * Expressions:: Some guidance on programming expression-oriented classes * Headers:: Header files and other support for interfacing C++ to C * Builtin:: Utility functions for builtin types * New:: Library dynamic allocation primitives * IOStream:(iostream)Top. The input/output library (istreams and ostreams). * Stream:: obsolete I/O library * Obstack:: Obstacks and their uses. * AllocRing:: A place to store objects for a while * String:: String, SubString, and Regex classes. * Integer:: Multiple precision Integer class. * Rational:: Multiple precision Rational class * Complex:: Complex number class * Fix:: Fixed point proportion classes * Bit:: BitSet and BitString classes * Random:: Random number generators * Data:: SampleStatistic and related classes for data collection * Curses:: CursesWindow class * List:: Lisp-like List prototype * LinkList:: Singly and doubly linked list class prototypes * Vector:: Vector prototypes * Plex:: Plex (adjustable array) prototypes * Stack:: Stack prototypes * Queue:: Queue prototypes * Deque:: Double ended queue prototypes * PQ:: Heap (priority queue) class prototypes * Set:: Set class prototypes * Bag:: Bag class prototypes * Map:: Map (Associative array) prototypes * GetOpt:: C++ class-based version of the GNU/UNIX getopt function * Projects:: Things Still Left to do  File: libg++.info, Node: Copying, Next: Contributors, Prev: Top, Up: Top GNU LIBRARY GENERAL PUBLIC LICENSE ********************************** Version 2, June 1991 Copyright (C) 1991 Free Software Foundation, Inc. 675 Mass Ave, Cambridge, MA 02139, USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. 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SIGNATURE OF TY COON, 1 April 1990 Ty Coon, President of Vice That's all there is to it!  File: libg++.info, Node: Contributors, Next: Installation, Prev: Copying, Up: Top Contributors to GNU C++ library ******************************* Aside from Michael Tiemann, who worked out the front end for GNU C++, and Richard Stallman, who worked out the back end, the following people (not including those who have made their contributions to GNU CC) should not go unmentioned. * Doug Lea contributed most otherwise unattributed classes. * Per Bothner contributed the iostream I/O classes. * Dirk Grunwald contributed the Random number generation classes, and PairingHeaps. * Kurt Baudendistel contributed Fixed precision reals. * Doug Schmidt contributed ordered hash tables, a perfect hash function generator, and several other utilities. * Marc Shapiro contributed the ideas and preliminary code for Plexes. * Eric Newton contributed the curses window classes. * Some of the I/O code is derived from BSD 4.4, and was developed by the University of California, Berkeley. * The code for converting accurately between floating point numbers and their string representations was written by David M. Gay of AT&T.  File: libg++.info, Node: Installation, Next: Trouble, Prev: Contributors, Up: Top Installing GNU C++ library ************************** 1. Read through the README file and the Makefile. Make sure that all paths, system-dependent compile switches, and program names are correct. 2. Check that files `values.h', `stdio.h', and `math.h' declare and define values appropriate for your system. 3. Type `make all' to compile the library, test, and install. Current details about contents of the tests and utilities are in the `README' file.  File: libg++.info, Node: Trouble, Next: General, Prev: Installation, Up: Top Trouble in Installation *********************** Here are some of the things that have caused trouble for people installing GNU C++ library. 1. Make sure that your GNU C++ version number is at least as high as your libg++ version number. For example, libg++ 1.22.0 requires g++ 1.22.0 or later releases. 2. Double-check system constants in the header files mentioned above.  File: libg++.info, Node: General, Next: Conventions, Prev: Trouble, Up: Top GNU C++ library aims, objectives, and limitations ************************************************* The GNU C++ library, libg++ is an attempt to provide a variety of C++ programming tools and other support to GNU C++ programmers. Differences in distribution policy are only part of the difference between libg++.a and AT&T libC.a. libg++ is not intended to be an exact clone of libC. For one, libg++ contains bits of code that depend on special features of GNU g++ that are either different or lacking in the AT&T version, including slightly different inlining and overloading strategies, dynamic local arrays, etc. All of these differences are minor. For example, while the AT&T and GNU stream classes are implemented in very different ways, the vast majority of C++ programs compile and run under either version with no visible difference. Additionally, all g++-specific constructs are conditionally compiled; The library is designed to be compatible with any 2.0 C++ compiler. libg++ has also contained workarounds for some limitations in g++: both g++ and libg++ are still undergoing rapid development and testing--a task that is helped tremendously by the feedback of active users. This manual is also still under development; it has some catching up to do to include all the facilities now in the library. libg++ is not the only freely available source of C++ class libraries. Some notable alternative sources are Interviews and NIHCL. (InterViews has been available on the X-windows X11 tapes and also from interviews.stanford.edu. NIHCL is available by anonymous ftp from GNU archives (such as the pub directory of prep.ai.mit.edu), although it is not supported by the FSF - and needs some work before it will work with g++.) As every C++ programmer knows, the design (moreso than the implementation) of a C++ class library is something of a challenge. Part of the reason is that C++ supports two, partially incompatible, styles of object-oriented programming - The "forest" approach, involving a collection of free-standing classes that can be mixed and matched, versus the completely hierarchical (smalltalk style) approach, in which all classes are derived from a common ancestor. Of course, both styles have advantages and disadvantages. So far, libg++ has adopted the "forest" approach. Keith Gorlen's OOPS library adopts the hierarchical approach, and may be an attractive alternative for C++ programmers who prefer this style. Currently (and/or in the near future) libg++ provides support for a few basic kinds of classes: The first kind of support provides an interface between C++ programs and C libraries. This includes basic header files (like `stdio.h') as well as things like the File and stream classes. Other classes that interface to other aspects of C libraries (like those that maintain environmental information) are in various stages of development; all will undergo implementation modifications when the forthcoming GNU libc library is released. The second kind of support contains general-purpose basic classes that transparently manage variable-sized objects on the freestore. This includes Obstacks, multiple-precision Integers and Rationals, arbitrary length Strings, BitSets, and BitStrings. Third, several classes and utilities of common interest (e.g., Complex numbers) are provided. Fourth, a set of pseudo-generic prototype files are available as a mechanism for generating common container classes. These are described in more detail in the introduction to container prototypes. Currently, only a textual substitution mechanism is available for generic class creation.  File: libg++.info, Node: Conventions, Next: OK, Prev: General, Up: Top GNU C++ library stylistic conventions ************************************* * C++ source files have file extension `.cc'. Both C-compatibility header files and class declaration files have extension `.h'. * C++ class names begin with capital letters, except for `istream' and `ostream', for AT&T C++ compatibility. Multi-word class names capitalize each word, with no underscore separation. * Include files that define C++ classes begin with capital letters (as do the names of the classes themselves). `stream.h' is uncapitalized for AT&T C++ compatibility. * Include files that supply function prototypes for other C functions (system calls and libraries) are all lower case. * All include files define a preprocessor variable _X_h, where X is the name of the file, and conditionally compile only if this has not been already defined. The `#pragma once' facility is also used to avoid re-inclusion. * Structures and objects that must be publicly defined, but are not intended for public use have names beginning with an underscore. (for example, the `_Srep' struct, which is used only by the String and SubString classes.) * The underscore is used to separate components of long function names, e.g., `set_File_exception_handler()'. * When a function could be usefully defined either as a member or a friend, it is generally a member if it modifies and/or returns itself, else it is a friend. There are cases where naturalness of expression wins out over this rule. * Class declaration files are formatted so that it is easy to quickly check them to determine function names, parameters, and so on. Because of the different kinds of things that may appear in class declarations, there is no perfect way to do this. Any suggestions on developing a common class declaration formatting style are welcome. * All classes use the same simple error (exception) handling strategy. Almost every class has a member function named `error(char* msg)' that invokes an associated error handler function via a pointer to that function, so that the error handling function may be reset by programmers. By default nearly all call `*lib_error_handler', which prints the message and then aborts execution. This system is subject to change. In general, errors are assumed to be non-recoverable: Library classes do not include code that allows graceful continuation after exceptions.  File: libg++.info, Node: OK, Next: Proto, Prev: Conventions, Up: Top Support for representation invariants ************************************* Most GNU C++ library classes possess a method named `OK()', that is useful in helping to verify correct performance of class operations. The `OK()' operations checks the "representation invariant" of a class object. This is a test to check whether the object is in a valid state. In effect, it is a (sometimes partial) verification of the library's promise that (1) class operations always leave objects in valid states, and (2) the class protects itself so that client functions cannot corrupt this state. While no simple validation technique can assure that all operations perform correctly, calls to `OK()' can at least verify that operations do not corrupt representations. For example for `String a, b, c; ... a = b + c;', a call to `a.OK();' will guarantee that `a' is a valid `String', but does not guarantee that it contains the concatenation of `b + c'. However, given that `a' is known to be valid, it is possible to further verify its properties, for example via `a.after(b) == c && a.before(c) == b'. In other words, `OK()' generally checks only those internal representation properties that are otherwise inaccessible to users of the class. Other class operations are often useful for further validation. Failed calls to `OK()' call a class's `error' method if one exists, else directly call `abort'. Failure indicates an implementation error that should be reported. With only rare exceptions, the internal support functions for a class never themselves call `OK()' (although many of the test files in the distribution call `OK()' extensively). Verification of representational invariants can sometimes be very time consuming for complicated data structures.