Lazy_static
lazy_static is a Rust crate providing a macro for declaring static values initialized on first runtime access when compile-time initialization is insufficient.
Code Like a Pro in Rust
lazy_static is a Rust crate and macro that provides lazily initialized static values, including values initialized at runtime.
- How it is used
- Supports runtime-initialized global state and shared fixtures for parallel Rust unit tests.
- How deep it goes
- Explains macro usage, failed static initialization, atomic and mutex patterns, and generated lazy machinery.
- Examples
- Demonstrates atomic counters, Arc-wrapped counters, and mutex-protected test output.
- What you can do after
- Apply it via the lazy_static crate to define runtime-initialized static references for concurrent tests.
Learn Rust in a Month of Lunches
lazy_static is a Rust crate that provides statics initialized on first runtime access when compile-time constant initialization is insufficient.
- How it is used
- Creates global Rust statics whose values require runtime initialization rather than compile-time constant initialization.
- How deep it goes
- Explains syntax, generated dereference behavior, compiler failures, and a working logger, while deferring deeper macro internals.
- Examples
- Uses a global Logger with a Mutex-protected log vector, URL String, reqwest Client, compiler errors, and a completed logging program.
- What you can do after
- Apply it via the lazy_static crate to define and access global values requiring runtime construction.
Read how Learn Rust in a Month of Lunches explains lazy_static →
Related concepts
- once_cellalternative to · once_cell is a Rust crate providing single-assignment cells and facilities for lazily initialized global or static values.
- stateaddresses · State is information or a configuration describing the condition of a system, entity, or computation at a particular time and potentially influencing subsequent behavior or decisions.
- macrouses · A macro is a named construct that expands or transforms source code, commands, or templates before or during execution.
- lazy initializationpart of · Lazy initialization is a technique that postpones creating, retrieving, computing, or loading a value or resource until it is needed.
- thread localalternative to · Thread-local data is data whose value or instance is independently associated with each executing thread.
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