Miscellaneous fixes, especially to ObjC runtime description.

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@1143 72102866-910b-0410-8b05-ffd578937521

Documentation/gnustep-faq.texi

@@ -1,6 +1,6 @@
 @chapter GNUstep Frequently Asked Questions with Answers
 
-Last updated 3 March 1996.
+Last updated 11 March 1996.
 Maintained by Andrew McCallum <mccallum@@gnu.ai.mit.edu>, with
 contributions by Pascal Forget <pascal@@wsc.com>, Scott Christley
 <scottc@@net-community.com>, and Randy Chapman <chapman@@u.washington.edu>.
@@ -29,27 +29,26 @@ The GNUstep project consists of the following sub-projects:
 
 @itemize @bullet
 
-@item GNU Compiler and Objective-C Runtime Library - though not part of 
+@item GNU Objective C Compiler and Objective C Runtime Library -
-the GNUstep project per se, the GNU Compiler is used to compile 
+Although not actually a sub-project the GNUstep, GCC and the GNU
-Objective-C code and the Library is a fundamental part of any GNUstep 
+Objective C Runtime Library are integral to GNUstep, since they are used
-application.  Of particular interest to the GNUstep project is its 
+to make every GNU Objective C program.
-efficient thread-safe capability.
 
-@item GNUstep Base Library - code for non-graphical objects, such as
+@item GNUstep Base Library - Code for non-graphical objects, such as
 strings, collections, archiving support and distributed objects
 messaging.  (Including functionality similar to OpenStep's
 @samp{FoundationKit}.)
 
-@item GNUstep GUI Library - code for graphical objects used in making a
+@item GNUstep GUI Library - Code for graphical objects used in making a
 Graphical User Interface (GUI).  This includes buttons, sliders, text
 fields, windows, menus, etc.  (Including functionality similar to
 OpenStep's @samp{AppKit}.)
 
-@item GNUstep DisplayGhostScript Server - a server that draws PostScript
+@item GNUstep DisplayGhostScript Server - A server that draws PostScript
 graphics to the screen, and receives events from the keyboard and
 mouse.  It is based on GhostScript.
 
-@item GNUstep Interface Modeller Application - an application for
+@item GNUstep Interface Modeller Application - An application for
 graphically assembling application interfaces.
 
 @end itemize
@@ -68,16 +67,14 @@ the FAQ maintainer.
 
 The initial target platforms for GNUstep are Linux and other UN*X's.
 There has been some OS/2 WARP work, but I have not seen any ongoing work
-on this platform.
+on this platform yet, (contact McCallum if you are interested).
 
 
 @item What is the OpenStep standard?
 
 OpenStep is an Application Programming Interface (API) for creating
 applications using the Objective C language.  It was published by NeXT
-Computer Inc. in 1994.  It is being used by Sun Microsystems as part of
+Computer Inc. in 1994.
-their Common Desktop Environment (CDE), and it is being used by Ohio Carbon
-Blank as part of their On-line Virtual Community Project.
 
 OpenStep consists of three parts: the @samp{FoundationKit}, a library of
 non-graphical objects; the @samp{AppKit}, a library of objects usful in
@@ -209,7 +206,7 @@ can be found below.
 With free software, you should never, ever, believe promises about when
 a project will be finished.  ...However, that said: there are certain
 GNUstep developers that are counting on having useful Base and GUI
-libraries working by Summer 1996.
+libraries working by the end of Summer 1996.
 
 @item How can I help?
 
@@ -224,50 +221,87 @@ Andrew McCallum <mccallum@@gnu.ai.mit.edu>.
 More detailed inforation about each of the GNUstep sub-projects can be
 found below.
 
-@section GNU Compiler and Objective-C Runtime Library
+@section GNU Objective C Compiler and Objective C Runtime Library
 
 @enumerate
 
-@item What is the Objective-C Runtime Library?
+@item What is the Objective C Runtime Library?
 
-The Objective-C Runtime Library is a library of C functions and data 
+The Objective C Runtime Library provides C functions and data structures
-structures required to execute an Objective-C program.  There has been
+required to execute an Objective C program.  An introduction to the
-much written about the special capabilities of Objective-C; we refer you 
+Objective C Language is provided at
-to these resources to learn more about the language:
+@samp{http://www.next.com/Pubs/Documents/OPENSTEP/ObjectiveC/
+objctoc.htm}.  The Frequently Asked Questions list for
+@samp{comp.lang.objective-c} can be found at @samp{??}.
 
-NEXTSTEP Object-Oriented Programming And The Objective-C Language
+The GNU Objective C Runtime Library offers everything NeXT's runtime
-Addison-Wesley Publishing Company
+does, including Categories, Protocols, @samp{+poseAs:}, thread-safety,
-ISBN 0-201-63251-9
+class initialization on demand, delayed loading of classes, and
+initialization of static instances (such as @@""-style string objects). 
+
+It also has several improvements over NeXT's implementation:
+
+@itemize @bullet
+
+@item NeXT's runtime requires an extra function call (objc_msgSend) for
+each message that is sent; (the function looks up the receiving
+instance's implementation of the method).  GNU's implementation is
+faster because it does not use an extra function call.  Instead, it
+inlines a short piece of code that makes two pointer hops into a method
+dispatch table; because the code is inlined, it does not incur the
+overhead of a function call.
+
+@item When running in thread-safe mode, NeXT's runtime must aquire a
+global mutual exclusion lock every time a message is sent; this is
+extremely slow.  GNU's runtime, amazingly, sends messages just as fast
+in thread-safe mode as it does in single-thread mode---the code path
+does not contain even a single extra instruction!  The GNU runtime only
+needs locks when certainly structures are written, not read; the
+structures are written relatively infrequently: only at class
+initialization and when @samp{+poseAs:} is called.
+
+@item GNU's runtime provides ``selector-types'' along with each
+selector; NeXT's does not.  A selector-type is a string that describes
+the C variable types for the method's return and argument values.  Among
+other uses, selector-types is extrememly helpful for fast distributed
+objects implementations, (see GNUstep Base Library Section, below).
+
+@item Many of the GNU functions have different names than their
+corresponding NeXT functions; the GNU names conform to the GNU coding
+standards.
+
+@item GNU's runtime library has a new class heirarchy manipulating
+method called @samp{-transmuteClassTo:}.  It can change the class of an
+instance to a cousin class of the same instance-size.
+
+@item NeXT's compiler, @samp{cc}, is based on an old version of
+@samp{gcc}.  GNU's compiler is, of course, the latest version of
+@samp{gcc}, and therefore contains all the latest enhancements.
+
+@end itemize
 
-FSF's implementation utilizes a very efficient sparse array for storing
-and looking up selectors when performing method calls, and recently has
-been enhanced to provide thread safe operation that induces NO overhead
-to method calls.  It has full support for protocols and categories.
 
 @item What is its current state of development?
 
-As of this writing 2.7.2 is the most recent version of the GNU Compiler;
+GNU's Objective C Runtime library has been stable and useable since
-it can be obtained at any of the FSF's ftp archives.  This version does
+1993.  Enhancements continue to be made.
-not contain the patches for thread safe operation; though a later release
-of the compiler will, so you must apply the patch which is distributed
-with the GNUstep Base Library and recompile the Objective-C Runtime Library.
 
-The thread safe patch defines a number of functions for maintaining mutual
+The package @samp{gcc-2.7.2} contains the source for the GNU Objective C
-exclusion objects and threads.  The NSThread and NSLock type classes 
+compiler and runtime library.  It can be obtained from
-in the GNUstep Base Library are based upon these underlying functions, but
+@samp{ftp://prep.ai.mit.edu/pub/gnu}, or any other mirror of the GNU
-you can call them directly if you are not using GNUstep.  The implementation
+archives.  As far as I know, the GNU Objective C Runtime runs on all,
-is based upon a back-end program for the underlying operating system;
+platforms on which GCC runs.
-currently Microsoft Windows NT/95, SGI Unix, and Sun Unix have back-end
-tested implementations.  Volunteers are solicited for writing additional
-back-ends, especially one for Linux which is sorely needed.
 
-Additional detail about the implementation of thread safe operation can be
+GCC version 2.7.2 does not contain the thread-safe features, but the
-found in the source code and related documentation files.  The Library
+next version of GCC will.  A patch for thread-safe features is provided
-will still operate in a single, non-threaded, environment but any attempt
+with the latest developer snaphots of the GNUstep Base Library.  There
-to create a thread will return an error.
+are currently thread-safe backends for DEC OSF/1, Solaris, IRIX, and
+WindowsNT.  Volunteers are solicited for writing additional back-ends,
+especially one for Linux.
 
 @end enumerate
-@c GNU Compiler and Objective-C Runtime Library
+@c GNU Compiler and Objective C Runtime Library
+
 
 @section GNUstep Base Library
 
@@ -363,12 +397,12 @@ variety of enumeration methods based on invocations.
 @item OpenStep's archiving mechanism provides only one choice of backend
 format.  By backend format, I mean a format for writing C types, such as
 ints, floats and C strings.  The GNUstep archiving mechanism has a clear
-separation between frontend and backend.  Different backends backend's
+separation between frontend and backend.  Different backends are
-are provided.  One writes in human-readable and human-editable ASCII
+provided.  One backend writes in human-readable and human-editable ASCII
 text, (including programmer-provided text name labels for each of the
 items.)  Another writes in a compact, stream machine-independent bits.
 A third writes in an even more compact stream of machine-dependent bits;
-this is useful for a distributed objects connection on machines of the
+this is useful for distributed objects connections on machines of the
 same architecture.
 
 I'm not sure how OpenStep's archiving system implements forward
@@ -434,11 +468,11 @@ Collection                 Root all the collection classes (abstract)
         Queue              First in, first out
         Stack              First in, last out
         GapArray           Efficient handle middle insert and delete
-      LinkedList           More efficient than arrays for many ops
+      LinkedList           More efficient than arrays for some ops
 
 Strings (as in Smalltalk, part of the collection class heirarchy):
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-      ConstantString        Root of string classes, not changable
+      ConstantString        Root of string classes, chars not changable
         String              contents can be changed
         *CString            Strings based on 1-byte characters
 
@@ -529,6 +563,7 @@ It provides functionality that aims to implement the @samp{AppKit}
 portion of the OpenStep standard.  However the implementation has
 been written to take advantage of GNUstep enhancements wherever possible.
 
+
 @item Explain the organization of the front- and back-ends.
 
 The GNUstep GUI Library is divided into a front- and back-end.  The
@@ -558,13 +593,14 @@ A number of classes in the front-end are complete or almost complete;
 these include:  NSActionCell, NSButtonCell, NSButton, NSCell, NSControl,
 NSEvent, NSFont, NSResponder, and NSSlider.
 
-These classes are complete enough to use but still require some major
+Other classes are complete enough to use, but still require some major
-additions before being considered almost complete:  NSApplication, NSBox,
+additions before being considered almost complete: NSApplication, NSBox,
 NSColor, NSFontManager, NSMenu, NSMenuCell, NSPopUpButton, NSSliderCell,
 NSText, NSTextField, NSTextFieldCell, NSView, and NSWindow.
 
 All remaining classes have stub implementations.
 
+
 @item What is the current state of development of the X/DPS back-end?
 
 
@@ -602,28 +638,31 @@ able to find it in @samp{ftp://alpha.gnu.ai.mit.edu/gnu}.
 
 @item What is the Interface Modeller?
 
-Interface Modeller in its simplest form is an application for visually
+Interface Modeller, in its simplest form, is an application for visually
 constructing and prototyping graphical user interfaces.  At a more
-abstract level, it is a tool for connecting instances of Objective-C
+abstract level, it is a tool for connecting instances of Objective C
 classes to create a graph of objects; this graph is a model of an
 executable program that Interface Modeller can save to a file to be
 loaded and executed later outside of Interface Modeller.
 
 @item What is its current state of development?
 
-It is in the specification stage; no code has been written yet.  You
+It is in the specification stage; no code has been written yet.  The
-may read the current specifications at the GNUstep WWW pages.
+current specifications are available through the GNUstep WWW pages.
 
 @end enumerate
 @c GNUstep IM
 
-@format
 
+@ignore
 [Notes to FAQ contributors: Be succinct.  Stick to the facts.  Emphasize
 technical features that are already implemented; avoid writing about
-vague features without concrete ideas about their implementation; (the
+vague features without concrete ideas about their implementation.  Your
-IM section, for example, may be short?).  Your audience is future and
+audience is future and present code contributors to GNUstep, not
-present code contributors to GNUstep, not managers or publicity people.]
+managers or publicity people.]
+@end ignore
+
+@format
 
 
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