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# Introduction

gir is a tool to automatically generate safe wrappers for a C library with GObject introspection information. In order to use it you need the `.gir` file containing the introspection data for the library you want to create the bindings for, as well as the `.gir` files for all its dependencies. Have a look at the tutorial if you don't know how to find the .gir files. If your library does not provide a `.gir` file, unfortunately you cannot use gir, but maybe you can try rust-bindgen.

This book contains a tutorial on how to use gir. As an example we will create the bindings for Pango. In many cases you will be able to follow the same steps with your library. If you are already familiar with gir and you just want to look up details about the configuration files, feel free to skip ahead to the documentation of the configuration files.

## General steps

gir tries to make it as simple as possible to generate a safe wrapper for your C library. The process can be divided into four steps that correspond to the four operating modes gir has.

- Generating unsafe bindings: In this step, the low-level FFI bindings are created from the supplied `*.gir` files. These are essentially direct calls into the related C library and are unsafe. The resulting crate is typically appended with -sys. The operating mode is `sys`.

- Generating a safe wrapper: Next, another crate for a layer on top of these unsafe (sys) bindings is created, which makes them safe for use in general Rust. The operating mode is `normal`.

- Checking for missing types/methods: The operating mode `not_bound` allows you to see the detected types/methods that will not be generated for whatever reasons.

- Adding documentation: After the safe wrapper is created, gir can even generate the documentation for us. Use the operating mode `doc` to do so.

## Regenerating the bindings and wrapper

In order to generate the bindings and the wrapper for the first time, the above-mentioned steps should be followed. When you want to regenerate the crates because e.g. the library was updated, you can simplify the process by running the helper script `./generator.py`. The script detects `Gir.toml` configurations in the current directory and subdirectories (or the paths passed on the command-line) and generates "normal" or "sys" crates for it. Alternatively `--embed-docs` can be passed to prepare source-code for a documentation built by moving all documentation into it. For a complete overview of available options, pass `--help`.

## GIR format reference

It can always be useful to look at the reference or schema.

## Contact us

If you use gir on another library and it fails and you can't figure out why, don't hesitate to contact us!