InjectionIII is a macOS menu bar application that enables hot reloading of Swift, Objective-C, and C++ code in iOS simulators and devices. It works by watching for source file changes, recompiling them using Xcode build logs, and dynamically loading the resulting dylib into the running app using techniques like interposing, vtable patching, and Objective-C swizzling. The app consists of a daemon with a file watcher and injection server, while the client-side code (bundled as injection bundles or via the HotReloading Swift package) handles compilation and injection. It supports standalone injection without the app running, injection on real devices, and integration with SwiftUI. The codebase is mature and actively maintained, though it contains legacy C/ObjC components and is tightly coupled to Xcode build log parsing.
AREPL is a VS Code extension that evaluates Python code in real-time as you type, displaying variables, errors, and print output in a side panel. It provides a scratchpad-like experience for Python development, with features like real-time evaluation, variable inspection, error display, and support for dumping variables from functions. The extension uses a Python backend (arepl-backend npm package) to execute code and communicate results via JSON. The TypeScript architecture includes a PreviewManager that orchestrates execution and preview updates, a PreviewContainer that manages the webview, and separate modules for inline errors (PythonInlinePreview) and panel display (PythonPanelPreview). The codebase is well-structured with clear separation of concerns, includes unit tests (mocha), and uses telemetry for diagnostics. The extension is maintained (last release November 2024) and uses modern dependencies.