pocketpy/docs/quick-start/installation.md
2023-07-18 17:48:39 +08:00

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---
icon: dot
label: 'Installation'
order: 100
---
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.
If you use [Dear ImGui](https://github.com/ocornut/imgui), we provide official bindings for it. See [pkpy-imgui](https://github.com/blueloveTH/pkpy-imgui) for details.
### 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!')", "main.py", EXEC_MODE);
// Create a list
vm->exec("a = [1, 2, 3]", "main.py", EXEC_MODE);
// Eval the sum of the list
PyObject* result = vm->exec("sum(a)", "<eval>", EVAL_MODE);
std::cout << CAST(int, result); // 6
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.
You need to use the C++ `new` operator to create a `VM` instance.
Do not declare it on the stack.
```cpp
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 priviledged modules such os `io` and `os` as well as builtin function `open`.
When you are done with the `VM` instance, use `delete` operator to dispose it.
```cpp
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:
```cpp
typedef void(*PrintFunc)(VM*, const Str&);
```