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name: m01-ownership description: "CRITICAL: Use for ownership/borrow/lifetime issues. Triggers: E0382, E0597, E0506, E0507, E0515, E0716, E0106, value moved, borrowed value does not live long enough, cannot move out of, use of moved value, ownership, borrow, lifetime, 'a, 'static, move, clone, Copy, 所有权, 借用, 生命周期"

Ownership & Lifetimes

Layer 1: Language Mechanics

Core Question

Who should own this data, and for how long?

Before fixing ownership errors, understand the data's role:

• Is it shared or exclusive?
• Is it short-lived or long-lived?
• Is it transformed or just read?

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Error → Design Question

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Thinking Prompt

Before fixing an ownership error, ask:

1. What is this data's domain role?

   • Entity (unique identity) → owned
   • Value Object (interchangeable) → clone/copy OK
   • Temporary (computation result) → maybe restructure

2. Is the ownership design intentional?

   • By design → work within constraints
   • Accidental → consider redesign

3. Fix symptom or redesign?

   • If Strike 3 (3rd attempt) → escalate to Layer 2

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Trace Up ↑

When errors persist, trace to design layer:

CopyE0382 (moved value)
    ↑ Ask: What design choice led to this ownership pattern?
    ↑ Check: m09-domain (is this Entity or Value Object?)
    ↑ Check: domain-* (what constraints apply?)

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Trace Down ↓

From design decisions to implementation:

Copy"Data needs to be shared immutably"
    ↓ Use: Arc<T> (multi-thread) or Rc<T> (single-thread)

"Data needs exclusive ownership"
    ↓ Use: move semantics, take ownership

"Data is read-only view"
    ↓ Use: &T (immutable borrow)

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Quick Reference

Error Code Reference

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Anti-Patterns

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Related Skills