Module graph_builder 

Lifetimes - Rust Book Chapter 10.3

This module demonstrates lifetime annotations from The Rust Book Chapter 10.3.

Key Concepts Demonstrated

1. Lifetime Parameters on Structs (Chapter 10.3)

   • CallGraphBuilder<'a> holds references with lifetime 'a
   • Prevents the struct from outliving its referenced data
   • Zero-cost abstraction - no runtime overhead

2. Why Lifetimes Matter

   • Prevent dangling references at compile time
   • Enable borrowing without ownership transfer
   • Alternative to heap allocation (Box) or reference counting (Rc)

3. When You Need Explicit Lifetimes

   • Structs that store references
   • Functions returning references
   • Multiple references with different lifetimes

Learning Notes

Most code doesn’t need explicit lifetimes!

• Rust has “lifetime elision” rules that infer lifetimes
• You only write lifetimes when Rust can’t figure them out
• This module is a good example of when they’re necessary

The lifetime syntax:

• 'a - A lifetime parameter (can be any name: 'b, 'lifetime, etc.)
• &'a T - A reference to T that lives for lifetime 'a
• &'a mut T - A mutable reference to T that lives for lifetime 'a

Common lifetime names:

• 'a, 'b, 'c - Generic lifetime parameters
• 'static - Special lifetime for the entire program duration

Structs

CallGraphBuilder

Builds a call graph by recursively tracing function calls.

CallNode

A node in the call graph tree

CallTree

Represents a complete call graph tree

Enums

TraceDirection

Direction of the call graph trace