Book: Complete Guide to Go Programming

Also by me: Thinking in Go (2-book series) — Complete Guide to Go Programming + Hexagonal Architecture in Go

My project: Hermes IDE | GitHub — an IDE for developers who ship with Claude Code and other AI coding tools

Me: xgabriel.com | GitHub

Open any Go codebase past a year old and you will hit this pattern:

var ( cfgOnce sync . Once cfg * Config cfgErr error )

func GetConfig () ( * Config , error ) { cfgOnce . Do ( func () { cfg , cfgErr = loadConfig () }) return cfg , cfgErr }

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Three package-level variables. A closure that mutates two of them by name. A function that reads them after Do returns. It works. It has worked since Go 1.0.…