Python 3.12 introduces language and interpreter-level enhancements centered on error diagnostics, execution performance, and the type system. Performance gains derive from PEP 709's comprehension inlining—eliminating per-comprehension function frames—alongside object-size reductions and the introduction of immortal objects, which are objects whose reference count is never mutated because they are never deallocated, reducing cache invalidation and enabling future thread-safe sharing across per-interpreter GILs (sub-interpreters). On the type-system side, PEP 695 introduces dedicated syntax for generic classes, functions, and type aliases, replacing the prior `TypeVar`-based mechanism with a simpler, more concise declaration form that maps more closely to generics syntax in other statically-typed languages.
Python 3.12 introduces language and interpreter-level enhancements centered on error diagnostics, execution performance, and the type system. Performance gains derive from PEP 709's comprehension inl…