Debunking the Rust Hype: Why It's Not Always a Good Replacement for C++

posted Sat, Sep 30, 2023 by darren horrocks

In recent years, Rust has gained significant attention and popularity in the programming community. Advocates often tout it as a worthy successor to C++, promising safer and more efficient systems programming. While Rust certainly has its merits, it’s essential to recognise that it may not always be the best fit for every scenario. In this article, we’ll explore some of the reasons why Rust may not necessarily be a superior replacement for C++.

Learning Curve

One of the most significant challenges when adopting Rust is its steep learning curve. C++ developers, especially those with extensive experience, might find it particularly challenging to transition to Rust due to its unique ownership model and strict borrowing rules. This can result in a considerable investment of time and resources in retraining existing teams or hiring new ones proficient in Rust.

Mature Ecosystem

C++ has a well-established and extensive ecosystem of libraries, frameworks, and tools that have evolved over decades. In contrast, Rust’s ecosystem is still relatively young and may not offer the same breadth and depth of resources. For specialised domains or legacy systems, finding equivalent Rust libraries or tools can be a daunting task, potentially leading to project delays or compromises in functionality.

Performance Trade-offs

While Rust’s emphasis on safety is commendable, it comes at a cost. The strict ownership model and borrow checker can introduce overhead, impacting runtime performance compared to C++. In scenarios where raw performance is paramount, such as real-time systems or high-frequency trading applications, C++ may still hold a distinct advantage.

Lack of Legacy Code Compatibility

For projects with existing codebases in C++ or interdependent legacy systems, migrating to Rust might not be a straightforward process. Rewriting or retrofitting existing code to work with Rust’s ownership model can be a substantial undertaking, potentially outweighing the benefits gained from Rust’s safety guarantees.

Resource Constraints

In certain resource-constrained environments, such as embedded systems or IoT devices with limited memory and processing power, Rust’s runtime and memory management system may not be the most efficient choice. C++ provides more fine-grained control over memory allocation and deallocation, allowing for optimization in resource-constrained environments.

Industry Adoption and Support

C++ has been a cornerstone of system-level programming for decades and is deeply entrenched in many critical industries, including aerospace, gaming, finance, and telecommunications. The vast majority of existing codebases in these sectors are written in C++. The risk and cost associated with a wholesale transition to Rust, both in terms of retraining personnel and rewriting existing code, may not be justified by the perceived benefits.

In conclusion, while Rust brings significant advancements in safety and memory management to the table, it is not a one-size-fits-all replacement for C++. It’s crucial to assess the specific needs and constraints of a project before making a decision. In some cases, the benefits of adopting Rust may be outweighed by the challenges and costs associated with the transition. Ultimately, the choice between C++ and Rust should be driven by a thorough evaluation of the project’s requirements and the strengths of each language.