pocketpy/README.md

# pocketpy: python interpreter in 1 file

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**English |** [**简体中文**](README_zh.md)

pkpy is a lightweight(~10000 LOC) Python interpreter for game scripting, built on C++17 with STL.

It aims to be an alternative to lua for game scripting, with elegant syntax, powerful features and competitive performance.
pkpy is extremely easy to embed via a single header file `pocketpy.h`, without external dependencies.

Please see https://pocketpy.dev for details or try [Live Demo](https://pocketpy.dev/static/web/).

## Quick start

Download the `pocketpy.h` on our [GitHub Release](https://github.com/blueloveTH/pocketpy/releases) page.
And `#include` it in your project.

You can also use cmake to build it from source. See CMakeLists.txt for details.
These variables can be set to control the build process:
+ `PK_BUILD_STATIC_LIB` - Build the static library
+ `PK_BUILD_SHARED_LIB` - Build the shared library

If you are working with [Unity Engine](https://unity.com/), you can download our plugin [PocketPython](https://assetstore.unity.com/packages/tools/visual-scripting/pocketpy-241120) on the Asset Store.

### Compile flags

To compile it with your project, these flags must be set:

+ `--std=c++17` flag must be set
+ Exception must be enabled

### Example

```cpp
#include "pocketpy.h"

using namespace pkpy;

int main(){
    // Create a virtual machine
    VM* vm = new VM();

    // Hello world!
    vm->exec("print('Hello world!')");

    // Create a list
    vm->exec("a = [1, 2, 3]");

    // Eval the sum of the list
    PyObject* result = vm->eval("sum(a)");
    std::cout << CAST(int, result);   // 6

    // Bindings
    vm->bind(vm->_main, "add(a: int, b: int)",
      [](VM* vm, ArgsView args){
        int a = CAST(int, args[0]);
        int b = CAST(int, args[1]);
        return VAR(a + b);
      });

    // Call the function
    PyObject* f_add = vm->_main->attr("add");
    result = vm->call(f_add, VAR(3), VAR(7));
    std::cout << CAST(int, result);   // 10

    // Dispose the virtual machine
    delete vm;
    return 0;
}
```

## Features

Check this [Cheatsheet](https://reference.pocketpy.dev/python.html)
for a quick overview of the supported features.

| Name            | Example                         | Supported |
| --------------- | ------------------------------- | --------- |
| If Else         | `if..else..elif`                | YES       |
| Loop            | `for/while/break/continue`      | YES       |
| Function        | `def f(x,*args,y=1):`           | YES       |
| Subclass        | `class A(B):`                   | YES       |
| List            | `[1, 2, 'a']`                   | YES       |
| ListComp        | `[i for i in range(5)]`         | YES       |
| Slice           | `a[1:2], a[:2], a[1:]`          | YES       |
| Tuple           | `(1, 2, 'a')`                   | YES       |
| Dict            | `{'a': 1, 'b': 2}`              | YES       |
| F-String        | `f'value is {x}'`               | YES       |
| Unpacking       | `a, b = 1, 2`                   | YES       |
| Star Unpacking  | `a, *b = [1, 2, 3]`             | YES       |
| Exception       | `raise/try..catch`              | YES       |
| Dynamic Code    | `eval()/exec()`                 | YES       |
| Reflection      | `hasattr()/getattr()/setattr()` | YES       |
| Import          | `import/from..import`           | YES       |
| Context Block   | `with <expr> as <id>:`          | YES       |
| Type Annotation | `def  f(a:int, b:float=1)`      | YES       |
| Generator       | `yield i`                       | YES       |
| Decorator       | `@cache`                        | YES       |

## Contribution

All kinds of contributions are welcome.

- Submit a Pull Request
  - fix a bug
  - add a new feature
- Open an Issue
  - any suggestions
  - any questions

Check our [Coding Style Guide](https://pocketpy.dev/coding_style_guide/) if you want to contribute C++ code.

## Reference

+ [cpython](https://github.com/python/cpython)

  The official implementation of Python programming language.

+ [byterun](https://www.aosabook.org/en/500L/a-python-interpreter-written-in-python.html)

  An excellent learning material. It illustrates how Python's virtual machine works.

+ [box2d](https://box2d.org/)

  The world's best 2D physics engine, written by Erin Catto. `box2d` now becomes a built-in module in pkpy `v1.1.3` and later.


## License

pkpy is licensed under the [MIT License](http://opensource.org/licenses/MIT).