How to Programmatically Retrieve Dependency Versions in build.rs for Rust Projects

Discover how to programmatically access dependency versions in Rust using `Cargo.toml`, eliminating the need for hardcoded values in your REPL's `build.rs` script.
---
This video is based on the question https://stackoverflow.com/q/75275761/ asked by the user 'elmattic' ( https://stackoverflow.com/u/161331/ ) and on the answer https://stackoverflow.com/a/75276470/ provided by the user 'rburmorrison' ( https://stackoverflow.com/u/12842747/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Retrieve the version of a dependency in build.rs script

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Programmatically Retrieve Dependency Versions in build.rs for Rust Projects

When working with Rust, particularly in scenarios where you need to expose functionality in your REPL (Read-Eval-Print Loop) built on top of libraries like Boa, it may become necessary to access the version of your JavaScript engine or any dependencies. If you find yourself hardcoding versions in your build.rs file, there is a simpler and more dynamic method to achieve this.

In this guide, we'll explore how to extract the version of your dependencies from Cargo.toml using the serde and toml crates, allowing you to avoid the pitfalls of hardcoded values and maintain more flexibility in your project.

Problem Statement

You may be attempting to expose the version of a JavaScript engine in your REPL, as illustrated below:

[[See Video to Reveal this Text or Code Snippet]]

In your main file, you would register this version:

[[See Video to Reveal this Text or Code Snippet]]

While the above works, it's not ideal as it requires manually updating the version in your build.rs file. Let's see how we can automate this process.

Solution Overview

Instead of hardcoding the versions, we can parse the Cargo.toml file directly using the serde and toml crates. This allows you to dynamically obtain the version of your dependencies as needed.

Step-by-Step Implementation

Add Dependencies: First, ensure to include serde and toml in your Cargo.toml under the [dependencies] section.

[[See Video to Reveal this Text or Code Snippet]]

Define the Data Structures: We need to define structures that will help us deserialize the Cargo.toml contents.

[[See Video to Reveal this Text or Code Snippet]]

Read and Parse Cargo.toml: Use the following code to read the Cargo.toml file and deserialize it into our structure.

[[See Video to Reveal this Text or Code Snippet]]

Output Interpretation

When you run the code, it will produce an output similar to:

[[See Video to Reveal this Text or Code Snippet]]

Using Dynamic Values

While include_str! provides a quick way to read the file, you may prefer to load the Cargo.toml dynamically. This would allow for more flexibility and prevent issues during the build process.

Conclusion

By utilizing the serde and toml crates, you can eliminate hardcoded dependency versions from your build.rs script, making your codebase cleaner and more maintainable. This method provides a programmatically dynamic way to access version information directly from Cargo.toml, allowing you to better manage dependencies in your Rust project.

Now, whenever you need to access a dependency's version, you can do so seamlessly! Happy coding!