Product Overview: Cling
What is Cling?
Cling is an interactive C interpreter developed by the team behind CERN’s ROOT data analysis framework. It is built on top of the LLVM and Clang compiler infrastructure, providing a high-performance and dynamic environment for C development.
Key Features
1. Interactive C REPL
Cling offers a read-eval-print loop (REPL) similar to Unix shells, allowing users to test C code snippets immediately without the need for a full compile-run-debug cycle. This feature is particularly useful for rapid prototyping, learning C , and exploring language features.
2. Production-Grade Parser and JIT Compiler
Cling leverages the Clang parser, enabling it to parse everything that Clang can, including C extensions specific to the interpreter. It also uses a just-in-time (JIT) compiler, allowing for the dynamic compilation and execution of code without the need for wrappers.
3. Emacs-like Command Line Editor
Cling features an interactive command line with Emacs bindings, providing a familiar and efficient interface for users. It automatically includes necessary header files and sets up a minimal runtime environment upon startup.
4. Metaprocessor Commands
Cling includes a metaprocessor that allows users to execute various commands to manage the interpreter’s state. Examples include loading files or libraries, adding include paths, and displaying the abstract syntax tree (AST) of processed code.
5. Runtime-Generated Code and Dynamic Interoperability
Cling supports the generation of code at runtime, which can interface with existing C libraries. It also aims to provide dynamic interoperability between C and other languages like Python, Julia, and Swift, enhancing its utility in heterogeneous environments.
6. Embedding and Customization
The functionality of Cling can be embedded into other applications, allowing these applications to benefit from an interactive C environment. This involves initializing the Cling interpreter within the main program and optionally passing command-line arguments.
7. Error Handling and Code Transformations
Cling includes advanced error recovery mechanisms, such as protecting against null pointer dereferences and managing storage for non-copyable or temporary objects. It also applies custom transformations to compiled code chunks before execution.
Use Cases
- Learning C : Cling provides immediate feedback, making it easier for users to get familiar with C structures and syntax.
- Scripting: Users can write and run small C scripts efficiently, similar to bash scripts.
- Rapid Application Development (RAD): Cling facilitates prototyping and proof-of-concept development by offering dynamic feedback during implementation.
- Runtime-Generated Code: It allows for the creation of code in response to user input, network data, or configuration changes.
- Research and Development: Cling is particularly useful in research environments, such as particle physics, where interactive exploration of C code is beneficial.
In summary, Cling is a powerful tool that enhances the C development process by providing an interactive, high-performance environment with robust features and extensive customization options.