Generics
Specialization in Rust and Why It Is Still Unstable
Specialization would let a blanket impl have faster special cases. After years of work it is still nightly only, held back by soundness problems with lifetimes.
7 min read
Topic
Generics
Traits, generics, trait objects and macros, and how to choose between them without fighting the compiler.
Generics
Enum Dispatch in Rust for Speed Without Trait Objects
When you know every implementor of a trait, an enum can stand in for a trait object with no allocation and with inlinable calls. The cost is a closed set.
7 min read
Generics
Dependency Injection in Rust With Traits and Generics
Rust needs no DI container. Define a trait for the dependency, take it in the constructor and wire the real types in main. Tests pass a fake instead.
8 min read
Generics
The Visitor Pattern in Rust With Traits and Enums Compared
In languages without sum types, the visitor pattern exists to add operations to a type hierarchy. Rust's enums and match usually make it unnecessary, with a few exceptions.
9 min read
Generics
Extension Traits in Rust to Add Methods to Foreign Types
Rust forbids adding inherent methods to foreign types, but a trait you define can. Extension traits are how itertools, futures and tokio add methods to the standard library.
8 min read
Generics
Any and Downcasting in Rust Trait Objects Explained
std::any::Any lets you ask a trait object what concrete type it holds. Learn downcast_ref, Box<dyn Any>, the as_any pattern for your own traits, and when an enum is the better design.
8 min read
Generics
Rust Error E0369 Binary Operation Cannot Be Applied
E0369 means an operator like + or == was used on a type that does not implement the matching trait. Fix it with a derive, a trait bound on the generic, or an explicit impl.
9 min read
Rust
The Newtype Pattern in Rust for Safer Function Signatures
A tuple struct with one field costs nothing at runtime and stops you passing a user id where an order id belongs. Learn construction, derives, Deref pitfalls and the orphan rule workaround.
8 min read
Generics
Writing a Derive Macro in Rust With Syn and Quote Explained
Build a custom derive from scratch with syn, quote and proc-macro2: parse the struct, generate an impl, report errors with spans and test the expansion.
3 min read
Generics
Macro Rules Basics in Rust With Patterns and Repetitions
macro_rules! matches token patterns and expands them into code. Learn fragment types, repetition and when a macro beats a function.
2 min read
Databases
Newtypes for Database IDs in Rust to Stop Mixing Them Up
Wrap IDs in tiny types so a UserId cannot be passed where an OrderId is expected. Derive sqlx::Type and Serde with transparent, and keep the cost at zero.
2 min read
Generics
Send and Sync in Rust Explained and Why They Are Auto Traits
Send means a value can move to another thread and Sync means a reference to it can be shared. See which types lack them and why the compiler decides for you.
9 min read
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