From 554fd8c5195424bdbcabf5de30fdc183aba391bd Mon Sep 17 00:00:00 2001 From: upstream source tree Date: Sun, 15 Mar 2015 20:14:05 -0400 Subject: obtained gcc-4.6.4.tar.bz2 from upstream website; verified gcc-4.6.4.tar.bz2.sig; imported gcc-4.6.4 source tree from verified upstream tarball. downloading a git-generated archive based on the 'upstream' tag should provide you with a source tree that is binary identical to the one extracted from the above tarball. if you have obtained the source via the command 'git clone', however, do note that line-endings of files in your working directory might differ from line-endings of the respective files in the upstream repository. --- libobjc/README | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 104 insertions(+) create mode 100644 libobjc/README (limited to 'libobjc/README') diff --git a/libobjc/README b/libobjc/README new file mode 100644 index 000000000..093116fd5 --- /dev/null +++ b/libobjc/README @@ -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 (manager), +Tom Wood (compiler) and Kresten Krab Thorup + (runtime) would like to thank a some people for +participating in the development of the present GNU Objective C. + +Paul Burchard and Andrew McCallum + has been very helpful debugging the +runtime. Eric Herring has been very helpful +cleaning up after the documentation-copyright disaster and is now +helping with the new documentation. + +Steve Naroff and Richard Stallman + 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. -- cgit v1.2.3