golang-patterns

Wrap errors with context using fmt.Errorf and the %w verb, define sentinel errors with errors.New for common cases, and create custom error types for domain-specific failures. Check errors with errors.Is and errors.As rather than string comparison, and never ignore errors with the blank identifier.

Use buffered channels or select statements with ctx.Done() so goroutines can exit when the context is cancelled. An unbuffered channel send blocks forever if no receiver exists, so always provide a cancellation path and coordinate shutdown with sync.WaitGroup or errgroup.

Functions should accept interfaces and return concrete structs. Define small, focused interfaces in the consumer package rather than the provider package, so implementations do not need to know about the interface they satisfy.

The functional options pattern configures a struct by passing variadic Option functions to a constructor, each setting one field. It provides sensible defaults while keeping the API extensible, avoiding large constructor parameter lists or config structs.

Use sync.Pool for frequently allocated objects like bytes.Buffer in hot paths to reduce garbage collection pressure. Always reset the object before returning it to the pool, and avoid it for objects that are cheap to allocate or rarely reused.

Run go vet, staticcheck, and golangci-lint with linters like errcheck, gosimple, ineffassign, unused, and gofmt enabled. Combine these with go test -race for race detection and go mod tidy to keep module dependencies clean.