--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libobjc/README	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,104 @@
+
+GNU Objective C notes
+*********************
+
+This document is to explain what has been done, and a little about how
+specific features differ from other implementations.  The runtime has
+been completely rewritten in gcc 2.4.  The earlier runtime had several
+severe bugs and was rather incomplete.  The compiler has had several
+new features added as well.
+
+This is not documentation for Objective C, it is usable to someone
+who knows Objective C from somewhere else.
+
+
+Runtime API functions
+=====================
+
+The runtime is modeled after the NeXT Objective C runtime.  That is,
+most functions have semantics as it is known from the NeXT.  The
+names, however, have changed.  All runtime API functions have names
+of lowercase letters and underscores as opposed to the
+`traditional' mixed case names.  
+	The runtime api functions are not documented as of now.
+Someone offered to write it, and did it, but we were not allowed to
+use it by his university (Very sad story).  We have started writing
+the documentation over again.  This will be announced in appropriate
+places when it becomes available.
+
+
+Protocols
+=========
+
+Protocols are now fully supported.  The semantics is exactly as on the
+NeXT.  There is a flag to specify how protocols should be typechecked
+when adopted to classes.  The normal typechecker requires that all
+methods in a given protocol must be implemented in the class that
+adopts it -- it is not enough to inherit them.  The flag
+`-Wno-protocol' causes it to allow inherited methods, while
+`-Wprotocols' is the default which requires them defined.
+
+
++load
+===========
+This method, if defined, is called for each class and category
+implementation when the class is loaded into the runtime.  This method
+is not inherited, and is thus not called for a subclass that doesn't
+define it itself.  Thus, each +load method is called exactly once by
+the runtime.  The runtime invocation of this method is thread safe.
+
+
++initialize 
+===========
+
+This method, if defined, is called before any other instance or class
+methods of that particular class.  For the GNU runtime, this method is 
+not inherited, and is thus not called as initializer for a subclass that 
+doesn't define it itself.  Thus, each +initialize method is called exactly 
+once by the runtime (or never if no methods of that particular class is 
+never called).  It is wise to guard against multiple invocations anyway 
+to remain portable with the NeXT runtime.  The runtime invocation of 
+this method is thread safe.
+
+
+Passivation/Activation/Typedstreams
+===================================
+
+This is supported in the style of NeXT TypedStream's.  Consult the
+headerfile Typedstreams.h for api functions.  I (Kresten) have
+rewritten it in Objective C, but this implementation is not part of
+2.4, it is available from the GNU Objective C prerelease archive. 
+   There is one difference worth noting concerning objects stored with
+objc_write_object_reference (aka NXWriteObjectReference).  When these
+are read back in, their object is not guaranteed to be available until
+the `-awake' method is called in the object that requests that object.
+To objc_read_object you must pass a pointer to an id, which is valid
+after exit from the function calling it (like e.g. an instance
+variable).  In general, you should not use objects read in until the
+-awake method is called.
+
+
+Acknowledgements
+================
+
+The GNU Objective C team: Geoffrey Knauth <gsk@marble.com> (manager),
+Tom Wood <wood@next.com> (compiler) and Kresten Krab Thorup
+<krab@iesd.auc.dk> (runtime) would like to thank a some people for
+participating in the development of the present GNU Objective C.
+
+Paul Burchard <burchard@geom.umn.edu> and Andrew McCallum
+<mccallum@cs.rochester.edu> has been very helpful debugging the
+runtime.   Eric Herring <herring@iesd.auc.dk> has been very helpful
+cleaning up after the documentation-copyright disaster and is now
+helping with the new documentation.
+
+Steve Naroff <snaroff@next.com> and Richard Stallman
+<rms@gnu.ai.mit.edu> has been very helpful with implementation details
+in the compiler.
+
+
+Bug Reports
+===========
+
+Please read the section `Submitting Bugreports' of the gcc manual
+before you submit any bugs.