GNUstep Objective-C Runtime
The GNUstep Objective-C runtime is designed as a drop-in replacement for the GCC runtime. It supports both a legacy and a modern ABI, allowing code compiled with old versions of GCC to be supported without requiring recompilation. The modern ABI adds the following features: - Non-fragile instance variables. - Protocol uniquing. - Object planes support. - Declared property introspection.