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(Why don't we separate the OpenStep standard classes from the

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GNU-specific classes?): New Q/A pair.
(Where can I get a copy?): Removed reference to Rochester's FTP site,
which will no longer be used, now that I'm at CMU.


git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@1698 72102866-910b-0410-8b05-ffd578937521
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mccallum 1996-09-04 15:29:29 +00:00
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Documentation/gnustep-faq.texi
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@ -473,6 +473,13 @@ type can already be found on the server, there is no need to ask the
client for the type, and GNU distributed objects takes two less network
hops.
@item OpenStep's distributed objects mechanism is based on a single
@i{Port} class. By contrast, GNU distributed objects makes use of a
heirarchy of Port objects that will provide the different ``back-ends''
appropriate to different situations. For example, the network back-end
for GNU distributed objects will be able to send messages using TCP,
UDP, local Unix sockets, or shared memory.
@item NeXT's Objective C runtime becomes very slow when thread-safety is
turned on since the runtime must acquire a global mutual-exclusion lock
each time an Objective C message is sent. GNUstep takes advantage of
@ -679,6 +686,69 @@ Packet holds data and reply port
@end format
@item @b{Why don't we separate the OpenStep standard classes from the GNU-specific classes?}
Just like @i{GCC} has more features than ANSI C, @i{gawk} has more
features than @i{awk}, and the @i{GNU C Library} has more features than
standard C Libraries, also, @i{GNUstep} has more features than
@i{OpenStep}. In all these cases, ``more features'' means some
combination of increased capabilities, and better time/space efficiency.
It is in keeping with the GNU tradition that GNU implementations are not
simply mindless copies of others standards, but that our implementations
include new improvements and creative solutions to previous annoyances.
In fact, Richard Stallman encourages innovation of this kind---not only
for the sake of better software---but also because it makes the legal
issues more clear: when the underlying implementation differs from the
proprietary implementation in significant, core, structural ways, it is
far more difficult for the proprietary entities to claim copyright
infringement.
With Steve Job's reputation for legal intimidation (e.g. the 1991
third-party D.O. implementation, WebRex, etc), the GNUstep community
certainly needs to concern itself with legal safety.
But the far more exciting reason for structural differences is the
increased efficiency and features that come from the changes. The item
above, ``@b{In what ways is the Base Library different from OpenStep's
FoundationKit?}'', explains some of the advantages that GNUstep's
organizational differences provide.
Many of these advantages are based on variations in class hierarchy, and
could not have been obtained by simply adding Category methods, or
subclasses to NeXT's structural organization. Using advantageous GNU
structure, providing the OpenStep standard interface on top of the GNU
implementations is quite straightforward, (and, when the mechanism is
understood, quite clean, also).
By analogy, consider the GNU C Library's @i{stdio} functionality. It is
based on a different underlying structure that provides new features not
found in standard @i{stdio} implementations. A @i{FILE*} can be opened
on a memory string that automatically grows as necessary; a @i{FILE*}
can be opened on a Mach port, where available. Using the generalized
underlying mechanism, it is straightforward to also implement the
standard @i{FILE*} opened on a UNIX file descriptor.
For example, the GNUstep NSArray class is implemented in much the same
way. GNUstep has a generalized collection class hierarchy with a deep
structure that provides common super classes in which a programmer can
add new functionality across all collection classes at once. It also
provides a simple powerful way to ensure uniformity of method names and
semantics across all collection class methods. It also provides more
efficient code sharing between classes. The @i{Array} class is part of
the GNUstep collection classes hierarchy; implementing @i{NSArray} in
terms of @i{Array} is straightforward. It avoids much duplicated code.
And it also provides users of NSArray with the extra GNU features;
(although, like in the GNU C Library, the GNUstep library user has the
option of turning off the availability of these extra features.)
In summary, the GNU project has often found that, while adding new
features to standard programs and libraries often requires more thought
and source code than standard implementations, it is worthwhile because
of the advantages of (1) better features, (2) increased time/space
efficiency, and (2) legal clarity. GNUstep is no exception.
@item @b{Where can I get a copy?}
The most recently released ``official'' version can be obtained from
@ -687,13 +757,6 @@ The most recently released ``official'' version can be obtained from
The most recently released alpha version can be obtained from
@url{ftp://alpha.gnu.ai.mit.edu}.
The most recent developer's snapshot can be obtained from
@url{ftp://ftp.cs.rochester.edu/pub/u/mccallum/gnustep-base}. These
releases are there for exchange between active GNUstep coders, and for
curious code-readers, not for naive users; read the README.first file in
the FTP directory.
@end enumerate
@c GNUstep Base Library