# Installation

You have two options to integrate pkpy into your project.

# Use the single header file

Download the pocketpy.h on our GitHub Release page. And #include it in your project. It is recommended to use the latest dev version.

# Use CMake

Clone the whole repository as a submodule in your project, You need Python 3 installed on your system because CMakeLists.txt requires it to generate some files.

In your CMakelists.txt, add the following lines:

option(PK_BUILD_STATIC_LIB "Build static library" ON)
target_link_libraries(your_target pocketpy)

    # exceptions must be enabled for emscripten

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

See CMakeLists.txt for details.

It is safe to use main branch in production.

# Compile flags

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

  • --std=c++17 flag must be set
  • Exception must be enabled
  • For MSVC, /utf-8 flag must be set

For emscripten, you must enable exceptions to make pocketpy work properly. See https://emscripten.org/docs/porting/exceptions.html.

# Get prebuilt binaries

We have prebuilt binaries, check them out on our GitHub Actions.

You can download an artifact there which contains the following files.

├── android
│   ├── arm64-v8a
│   │   └── libpocketpy.so
│   ├── armeabi-v7a
│   │   └── libpocketpy.so
│   └── x86_64
│       └── libpocketpy.so
├── ios
│   └── libpocketpy.a
├── linux
│   └── x86_64
│       ├── libpocketpy.so
│       └── main
├── macos
│   └── pocketpy.bundle
│       └── Contents
│           ├── Info.plist
│           └── MacOS
│               └── pocketpy
└── windows
    └── x86_64
        ├── main.exe
        └── pocketpy.dll

# Example

#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 << py_cast<int>(vm, result);   // 6

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

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

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

# Overview

pkpy's C++ interfaces are organized in an object-oriented way. All classes are located in pkpy namespace.

The most important class is the VM class. A VM instance is a python virtual machine which holds all necessary runtime states, including callstack, modules, variables, etc.

A process can have multiple VM instances. Each VM instance is independent from each other.

VM* vm = new VM();

The constructor can take 1 extra parameters.

# VM(bool enable_os=true)

  • enable_os, whether to enable OS-related features or not. This setting controls the availability of privileged modules such os io and os as well as builtin function open. It is designed for sandboxing.

When you are done with the VM instance, use delete operator to dispose it.

delete vm;

# Hook standard buffer

By default, pkpy outputs all messages and errors to stdout and stderr. You can redirect them to your own buffer by setting vm->_stdout and vm->_stderr.

These two fields are C function pointers PrintFunc with the following signature:

typedef void(*PrintFunc)(const char*, int)

Or you can override these two virtual functions:

    virtual void stdout_write(const Str& s){
        _stdout(s.data, s.size);

    virtual void stderr_write(const Str& s){
        _stderr(s.data, s.size);