README
1
2GNU Objective C notes
3*********************
4
5This document is to explain what has been done, and a little about how
6specific features differ from other implementations. The runtime has
7been completely rewritten in gcc 2.4. The earlier runtime had several
8severe bugs and was rather incomplete. The compiler has had several
9new features added as well.
10
11This is not documentation for Objective C, it is usable to someone
12who knows Objective C from somewhere else.
13
14
15Runtime API functions
16=====================
17
18The runtime is modeled after the NeXT Objective C runtime. That is,
19most functions have semantics as it is known from the NeXT. The
20names, however, have changed. All runtime API functions have names
21of lowercase letters and underscores as opposed to the
22`traditional' mixed case names.
23 The runtime api functions are not documented as of now.
24Someone offered to write it, and did it, but we were not allowed to
25use it by his university (Very sad story). We have started writing
26the documentation over again. This will be announced in appropriate
27places when it becomes available.
28
29
30Protocols
31=========
32
33Protocols are now fully supported. The semantics is exactly as on the
34NeXT. There is a flag to specify how protocols should be typechecked
35when adopted to classes. The normal typechecker requires that all
36methods in a given protocol must be implemented in the class that
37adopts it -- it is not enough to inherit them. The flag
38`-Wno-protocol' causes it to allow inherited methods, while
39`-Wprotocols' is the default which requires them defined.
40
41
42+initialize
43===========
44
45This method, if defined, is called before any other instance or class
46methods of that particular class. This method is not inherited, and
47is thus not called as initializer for a subclass that doesn't define
48it itself. Thus, each +initialize method is called exactly once (or
49never if no methods of that particular class is never called).
50Besides this, it is allowed to have several +initialize methods, one
51for each category. The order in which these (multiple methods) are
52called is not well defined. I am not completely certain what the
53semantics of this method is for other implementations, but this is
54how it works for GNU Objective C.
55
56
57Passivation/Activation/Typedstreams
58===================================
59
60This is supported in the style of NeXT TypedStream's. Consult the
61headerfile Typedstreams.h for api functions. I (Kresten) have
62rewritten it in Objective C, but this implementation is not part of
632.4, it is available from the GNU Objective C prerelease archive.
64 There is one difference worth noting concerning objects stored with
65objc_write_object_reference (aka NXWriteObjectReference). When these
66are read back in, their object is not guaranteed to be available until
67the `-awake' method is called in the object that requests that object.
68To objc_read_object you must pass a pointer to an id, which is valid
69after exit from the function calling it (like e.g. an instance
70variable). In general, you should not use objects read in until the
71-awake method is called.
72
73
74Acknowledgements
75================
76
77The GNU Objective C team: Geoffrey Knauth <gsk@marble.com> (manager),
78Tom Wood <wood@next.com> (compiler) and Kresten Krab Thorup
79<krab@iesd.auc.dk> (runtime) would like to thank a some people for
80participating in the development of the present GNU Objective C.
81
82Paul Burchard <burchard@geom.umn.edu> and Andrew McCallum
83<mccallum@cs.rochester.edu> has been very helpful debugging the
84runtime. Eric Herring <herring@iesd.auc.dk> has been very helpful
85cleaning up after the documentation-copyright disaster and is now
86helping with the new documentation.
87
88Steve Naroff <snaroff@next.com> and Richard Stallman
89<rms@gnu.ai.mit.edu> has been very helpful with implementation details
90in the compiler.
91
92
93Bug Reports
94===========
95
96Please read the section `Submitting Bugreports' of the gcc manual
97before you submit any bugs.
98
README.threads
1==============================================================================
2README.threads - Wed Nov 29 15:16:24 EST 1995
3------------------------------------------------------------------------------
4
5Limited documentation is available in the THREADS file.
6
7This version has been tested on Sun Solaris, SGI Irix, and Windows NT.
8It should also work on any single threaded system.
9
10Thanks go to the following people for help test and debug the library:
11
12 Scott Christley, scottc@ocbi.com
13 Andrew McCallum, mccallum@cs.rochester.edu
14
15galen
16gchunt@cs.rochester.edu
17
18Any questions, bug reports, etc should be directed to:
19
20Scott Christley, scottc@ocbi.com
21
22Please do not bug Galen with email as he no longer supports the code.
23
24==============================================================================
25Changes from prior releases (in revered chronological order):
26------------------------------------------------------------------------------
27
28* Fixed bug in copy part of sarray_realloc. I had an < which should
29 have been <=. (Bug report from Scott).
30
31------------------------------------------------------------------------------
32
33* Support for DEC OSF/1 is definitely broken. My programs always
34 seg-fault when I link with libpthreads.a.
35
36* Thread id's are no longer int's, but are instead of type
37 _objc_thread_t which is typedef'ed from a void *. An invalid thread
38 id is denoted by NULL and not -1 as before.
39
40------------------------------------------------------------------------------
41
42* Renamed thread-winnt.c to thread-win32.c to better reflect support
43 for the API on both Windows NT and Windows 95 platforms.
44 (Who knows, maybe even Win32s :-).
45
46* Fixed bugs in Win32 support as per report from Scott Christley.
47
48* Fixed bug in sarray_get as per report from Scott Christley.
49
50
51