OverviewHistoryStatsSecurity
npx skills add ...
Documentation
SKILL.md
npx skills add actionbook/rust-skills --skill m15-anti-pattern
Use when reviewing code for anti-patterns. Keywords: anti-pattern, common mistake, pitfall, code smell, bad practice, code review, is this an anti-pattern, better way to do this, common mistake to avoid, why is this bad, idiomatic way, beginner mistake, fighting borrow checker, clone everywhere, unwrap in production, should I refactor, 反模式, 常见错误, 代码异味, 最佳实践, 地道写法
npx skills add actionbook/rust-skills --skill m15-anti-pattern
Layer 2: Design Choices
Is this pattern hiding a design problem?
When reviewing code:
| Anti-Pattern | Why Bad | Better |
|---|---|---|
.clone() everywhere | Hides ownership issues | Proper references or ownership |
.unwrap() in production | Runtime panics | ?, expect, or handling |
Rc when single owner | Unnecessary overhead | Simple ownership |
unsafe for convenience | UB risk | Find safe pattern |
OOP via Deref | Misleading API | Composition, traits |
| Giant match arms | Unmaintainable | Extract to methods |
String everywhere | Allocation waste | &str, Cow<str> |
Ignoring #[must_use] | Lost errors | Handle or let _ = |
When seeing suspicious code:
Is this symptom or cause?
What would idiomatic code look like?
Does this fight Rust?
To design understanding:
| Anti-Pattern | Trace To | Question |
|---|---|---|
| Clone everywhere | m01-ownership | Who should own this data? |
| Unwrap everywhere | m06-error-handling | What's the error strategy? |
| Rc everywhere | m09-domain | Is ownership clear? |
| Fighting lifetimes | m09-domain | Should data structure change? |
To implementation (Layer 1):
| Rank | Mistake | Fix |
|---|---|---|
| 1 | Clone to escape borrow checker | Use references |
| 2 | Unwrap in production | Propagate with ? |
| 3 | String for everything | Use &str |
| 4 | Index loops | Use iterators |
| 5 | Fighting lifetimes | Restructure to own data |
| Smell | Indicates | Refactoring |
|---|---|---|
Many .clone() | Ownership unclear | Clarify data flow |
Many .unwrap() | Error handling missing | Add proper handling |
Many pub fields | Encapsulation broken | Private + accessors |
| Deep nesting | Complex logic | Extract methods |
| Long functions | Multiple responsibilities | Split |
| Giant enums | Missing abstraction | Trait + types |
| Error | Anti-Pattern Cause | Fix |
|---|---|---|
| E0382 use after move | Cloning vs ownership | Proper references |
| Panic in production | Unwrap everywhere | ?, matching |
| Slow performance | String for all text | &str, Cow |
| Borrow checker fights | Wrong structure | Restructure |
| Memory bloat | Rc/Arc everywhere | Simple ownership |
| Deprecated | Better |
|---|---|
| Index-based loops | .iter(), .enumerate() |
collect::<Vec<_>>() then iterate | Chain iterators |
| Manual unsafe cell | Cell, RefCell |
mem::transmute for casts | as or TryFrom |
| Custom linked list | Vec, VecDeque |
lazy_static! | std::sync::OnceLock |
.clone() without justification.unwrap() in library codepub fields with invariantsString where &str suffices#[must_use] warningsunsafe without SAFETY comment| When | See |
|---|---|
| Ownership patterns | m01-ownership |
| Error handling | m06-error-handling |
| Mental models | m14-mental-model |
| Performance | m10-performance |