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 instead of string comparison, and never silently ignore errors with the blank identifier.

Use buffered channels or select statements with ctx.Done() so goroutines can exit when the context is cancelled. Coordinate goroutines with errgroup or sync.WaitGroup, and always ensure channel sends have a receiver or a cancellation path.

The functional options pattern passes configuration as variadic Option functions to a constructor, letting callers set only the fields they need while defaults apply to the rest. It avoids long parameter lists and keeps constructors extensible without breaking existing callers.

Interfaces should be defined at the point of use, in the consumer package, describing only what that consumer needs. This keeps interfaces small, avoids coupling packages to concrete implementations, and makes testing with mocks straightforward.

Use sync.Pool for frequently allocated temporary objects like buffers in hot paths, such as request processing. Always reset the object before returning it to the pool, and avoid it for objects holding state that must not be shared.

Run gofmt and goimports for formatting, go vet for suspicious constructs, and golangci-lint with linters like errcheck, staticcheck, govet, ineffassign, and unused. Enable errcheck type-assertion checks and govet shadowing detection for stricter analysis.