On 31 Jan 2010, at 12:47, Michael Van Canneyt wrote: > On Sat, 30 Jan 2010, Jonas Maebe wrote: > >> It means/meant version one of the Objective-C language. The Objective-C >> language evolves semi-independently of the run time (you can write programs >> in Objective-C 2.0 running on i386 and ppc32, whose Objective-C runtime is >> version 1). Objective-C 2.0 (the language) features require Mac OS X 10.5 or >> later, while 1.0 features are available as of 10.0. > > Eh ? > > How can a programming language feature depend on an operating system ?
Objective-C, being a very dynamic language, relies on support in a runtime library for several language features (even method dispatching is handled using interaction with the runtime). Mac OS X 10.4 and earlier ship with a version of the runtime library that does not support all features added in the Objective-C 2.0 language. For example, it has no RTTI support for properties or garbage collected classes (GC requires for each class a layout in the rtti that describes which fields contain strong and which contain weak references to class instances). You could in theory build a newer version of the run time library and include that with your app, but given how dynamic linking is implemented in Mac OS X (the absolute path to a dynamic library is hardcoded in applications/libraries that use this library, in order to avoid accidentally loading a wrong/different version if it happens to be in the path), you'd probably end up with two versions of the Objective-C run time library in memory at the same time (one for your app, and one for the system libraries -- which would have exactly the same consequences as using an FPC app with an FPC library and both having their own copy of the rtl: no shared class hierarchy etc). So you'd have to replace the system version of the Objective-C runtime library with your copy, which is kind of not-done for third party apps. Jonas_______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
