How to disable a specific performance cop in RuboCop Performance?

Add the cop name to the Exclude list in your .rubocop.yml, similar to standard RuboCop. For example, to exclude Performance/Size, configure it under that cop's settings in the YAML file.

Does RuboCop Performance work with Ruby on Rails projects?

Yes, it integrates seamlessly with any Ruby project using RuboCop, including Rails. Just add the plugin to your RuboCop configuration and run it during linting to catch performance anti-patterns in Rails code.

What are common performance issues caught by RuboCop Performance?

It flags patterns like unnecessary object allocations in loops, inefficient string concatenation, and suboptimal use of methods like map vs. each. The official docs provide cop-specific examples and explanations.

RuboCop Performance vs standard RuboCop: what's the difference?

Standard RuboCop focuses on style, correctness, and best practices, while RuboCop Performance adds specialized cops for performance bottlenecks. They complement each other when used together in a linting pipeline.

Is RuboCop Performance compatible with Ruby 3.x?

Generally yes, but check the compatibility documentation as some cops may be version-specific. The project aims to support recent MRI versions, but verify for your specific setup to avoid false positives.

How to integrate RuboCop Performance into a CI/CD pipeline?

Include rubocop-performance in your Gemfile, configure it via .rubocop.yml with the plugins key, and run rubocop as part of your CI script. Ensure RuboCop version 1.72+ for plugin support, or use the require method for older versions.

Open-Awesome

Rubocop Performance

MITRubyv1.27.0

A RuboCop extension that adds performance-focused static analysis to detect inefficient Ruby code patterns.

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742 stars96 forks0 contributors

What is Rubocop Performance?

RuboCop Performance is a plugin for RuboCop that adds specialized static analysis rules focused on detecting performance issues in Ruby code. It helps developers identify inefficient patterns, such as unnecessary object allocations or slow collection operations, before they impact application speed. The extension integrates seamlessly with existing RuboCop workflows to make performance optimization part of routine code review.

Target Audience

Ruby developers and teams using RuboCop for code quality who want to proactively identify and fix performance bottlenecks in their codebase, particularly those targeting MRI (Matz's Ruby Interpreter).

Value Proposition

It provides automated, consistent performance checks that catch common inefficiencies early, reducing manual review effort and helping teams maintain fast Ruby applications. As a dedicated extension, it offers more focused and version-aware performance analysis than generic linting tools.

Overview

An extension of RuboCop focused on code performance checks.

Use Cases

Best For

Adding automated performance checks to an existing RuboCop setup
Identifying inefficient string and collection operations in Ruby code
Enforcing performance best practices across a Ruby team
Catching MRI-specific performance anti-patterns during development
Integrating performance analysis into CI/CD pipelines for Ruby projects
Educating developers about common Ruby performance pitfalls through automated feedback

Not Ideal For

Projects running on non-MRI Ruby implementations like JRuby or TruffleRuby
Teams that haven't integrated RuboCop into their development workflow
Applications requiring runtime profiling for performance tuning rather than static analysis

Pros & Cons

Pros

Specialized Performance Detection

Targets common inefficiencies like redundant string allocations and slow collection operations, with detailed examples in the cop documentation.

MRI-Specific Optimization

Cops are tailored for MRI and consider version-specific performance characteristics, making checks relevant to the primary Ruby runtime.

Seamless RuboCop Integration

Works as a plugin that easily adds performance checks to existing RuboCop workflows via .rubocop.yml or command line, as shown in the usage instructions.

Configurable Rule Set

Each performance cop can be enabled, disabled, or configured individually using standard RuboCop configuration files, offering flexibility.

Cons

MRI-Only Focus

Limited to MRI runtimes and may not apply to other implementations like JRuby, as admitted in the compatibility notes.

Version Dependency

Performance cops are highly dependent on MRI versions, requiring updates and adjustments that can break or mislead on older or newer Ruby releases.

Static Analysis Limitations

Cannot detect runtime-specific performance issues, such as those dependent on database queries or external APIs, making it incomplete for full optimization.

Frequently Asked Questions

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