Wrenpp

Wrenpp is a lightweight C++ wrapper for the official Wren C library. It aims to package all the features accessible through the C API in a modern C++ interface that is easy to use, while keeping the overhead to a minimum.

• Building
  • Wrenpp
  • Wren only
• Usage
  • Meson
  • C++
    • Header files
    • Initialisation

Building

Wrenpp

You can make a release build like this:

mkdir build
cd build
meson setup -Dbuildtype=release ..
ninja

The build scripts understand the following options (double check in meson_options.txt):

1. build_testing set to true to compile Wren's unit tests too
2. build_examples set to true to include examples from the examples/ directory in the build
3. wren_with_cli set to false to exclude the command line tool from the Wren subproject build
4. wren_with_rand set to true to compile Wren with random support
5. wren_with_meta set to true to compile Wren with meta support

Note that some example projects require random support in Wren, without which they will crash. If you want to run examples or you are getting "Address boundary error" segfaults recompile Wrenpp after enabling the example and/or meta options:

mkdir build
cd build
meson setup -Dbuildtype=debug -Dbuild_examples=true -Dwren_with_rand=true -Dwren_with_meta=true ..
ninja

Wren only

If you only want to compile the C library of Wren, of course you can do that:

mkdir build
cd build
meson setup -Dbuildtype=release -Dwren_with_rand=true -Dwren_with_meta=true ../subprojects/wren
ninja

This will build Wren as a shared object. If you want a static library instead you can add the -Ddefault_library=static parameter to your Meson command, or -Ddefault_library=both if you want tboth the shared and the static version of Wren.

Usage

Meson

You can use Wrenpp as a Meson subproject like you would do normally. For example:

wrenpp = subproject('wrenpp', default_options: ['wren_with_rand=true'])
wrenpp_dep = wrenpp.get_variable('wrenpp_dep')

executable('my_project',
  'main.cpp',
  dependencies: wrenpp_dep,
)

This will make Wrenpp build as part of your project with Wren's optional random module enabled.

Alternatively you can use the subproject as a fallback if there is no Wrenpp installed in your system already:

wrenpp_dep = dependency('wrenpp', version: '>=0.1.0',
  fallback: ['wrenpp', 'wrenpp_dep'],
  default_options: ['wren_with_rand=true'],
)

Note that when you use Wrenpp as a subproject, Wrenpp's subproject Wren will become a sub-subproject of your project. This is how Meson works and it simply means that in your top level source directory you will have to run this command before you will be able to compile (Meson should detect and print this as well):

meson wrap promote subprojects/wrenpp/subprojects/wren

C++

For working examples refer to the source files in the examples/ directory.

Header files

In order to use Wrenpp in your project you will need to include wrenpp/vm.hpp at least. A description of all the relevant header files follows:

• vm.hpp The VM class provides simple wrappers around the C API functions. It wraps and hides the WrenVM pointer and provides RAII around it. Available methods aim to be as close to their C counterparts as possible. You can use objects of this class in a way that mirrors very closely the way you would use the C API.
• vm_fun.hpp This header provides functions on top of the VM class. Their goal is to make common operations easier and more compact in your code.
• def_configuration.hpp The DefConfiguration struct extends the bare Configuration struct by providing an implementation for write_fn, error_fn and reallocate_fn. They are implemented in terms of std::cout, std::cerr and new[]/delete[] respectively. You can safely ignore this header if this is not suitable for your project.

Other header files are intended for Wrenpp's use and you shouldn't need to use them. You are free to use them in your project if you think the code inside is useful to you, however keep in mind that those are not providing core Wrenpp functionalities and may be removed or modified in the future.

Initialisation

Wrenpp aims to make your code as clear and concise as possible. To instantiate a VM (which wraps WrenVM) and run a simple script you can do the following:

#include <wrenpp/vm.hpp>
#include <wrenpp/def_configuration.hpp>

int main() {
	wren::DefConfiguration config;
	wren::VM vm(&config, nullptr);

	vm.interpret("main", "System.print(\"Hello world!\")");
	return 0;
}

Work in progress