Practical Go for Developers

This repo contains the material for the "Practical Go Foundations" class. The code & links are synced with the [online class](for Developers).

This is an assorted collection of exercises for teaching, not a real Go project.

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Day 1

Agenda

• Strings & formatted output
  • What is a string?
  • Unicode basics
  • Using fmt package for formatted output
• Calling REST APIs
  • Making HTTP calls with net/http
  • Defining structs
  • Serializing JSON
• Working with files
  • Handling errors
  • Using defer to manage resources
  • Working with io.Reader & io.Writer interfaces

Code

• hw.go - Hello World
  • GOOS=drawin go build (also GOARCH)
• banner.go - Strings & printing
• github.go - Calling REST APIs
• sha1.go - Working with io.Reader & io.Writer

Terminal Log

Links

• HTTP status cats
• errors package (Go 1.13)
• encoding/json
• net/http
• Let's talk about logging by Dave Cheney
• Numbers
  • math/big - Big numbers
  • Numeric types
• Strings
  • Unicode table
  • strings package - string utilities
  • Go strings
• Annotated "Hello World"
• Effective Go - Read this!
• Go standard library - official documentation
• A Tour of Go
• Setting Up
  • The Go SDK
  • git
  • IDE's: Visual Studio Code + Go extension or Goland (paid)

Data & Other

• G☺
• ♡
• http.log.gz

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Day 2

Agenda

• Sorting
  • Working with slices
  • Writing methods
  • Understanding interfaces
• Catching panics
  • The built-in recover function
  • Named return values
• Processing text
  • Reading line by line with bufio.Scanner
  • Using regular expressions
  • Working with maps

Code

• slices.go - Working with slices
• game.go - Structs, methods & interfaces
• empty.go - The empty interface, type assertions
• div.go - Catching panics
• freq.go - Most common word (files, regular expressions, maps)

Terminal Log

Exercises

• Read and understand the sort package examples
• Implement sortByDistance(players []Player, x, y int) in game.go
• Change mostCommon to return the most common n words (e.g. func mostCommon(r io.Reader, n int) ([]string, error))

Links

• regex101 - Regular expression builder
• Go Proverbs - Think about them ☺
• sort examples - Read and try to understand
• When to use generics
• Generics tutorial
• Methods, interfaces & embedded types in Go
• Methods & Interfaces in the Go tour
• Slices
  • Slices & Slice internals on the Go blog
  • Slice tricks
• Error Handling
  • Defer, Panic and Recover
  • errors package (Go 1.13)
  • pkg/errors

Data & Other

• sherlock.txt

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Day 3

Agenda

• Distributing work
  • Using goroutines & channels
  • Using the sync package to coordinate work
• Timeouts & cancellation
  • Working with multiple channels using select
  • Using context for timeouts & cancellations
  • Standard library support for context

Code

• go_chan.go - Goroutines & channels
  • sleep_sort.sh - Sleep sort in bash
• taxi_check.go - Turn sequential code to parallel
• sites_time.go - Using sync.WaitGroup
• payment.go - Using sync.Once & sync.WaitGroup
• counter.go - Using the race detector, sync.Mutex and sync/atomic
• select.go - Using select
• rtb.go - Using context for cancellations

Terminal Log

Exercise

In taxi_check.go

• Limit the number of goroutines to "n". Which "n" yields the best results?
• Cancel all goroutines once there's an error or mismatch in signature

Links

• The race detector
• Uber Go Style Guide
• errgroup
• Data Race Patterns in Go
• Go Concurrency Patterns: Pipelines and cancellation
• Go Concurrency Patterns: Context
• Curious Channels
• The Behavior of Channels
• Channel Semantics
• Why are there nil channels in Go?
• Amdahl's Law - Limits of concurrency
• Computer Latency at Human Scale
• Concurrency is not Parallelism by Rob Pike
• Scheduling in Go

Data & Other

• rtb.go
• site_times.go
• taxi_check.go
  • taxi-sha256.zip

---

Day 4

Agenda

• Testing your code
  • Working with the testing package
  • Using testify
  • Managing dependencies with go mod
• Structuring your code
  • Writing sub-packages
• Writing an HTTP server
  • Writing handlers
  • Using gorilla/mux for routing Adding metrics & logging
  • Using expvar for metrics
  • Using the log package and a look at user/zap
• Configuration patterns
  • Reading environment variables and a look at external packages
  • Using the flag package for command line processing

Code

nlp project

├── go.mod - Project & dependencies
├── nlp.go - Package code
├── doc.go - Package level documentation
├── nlp_test.go - Test & benchmark file
├── example_test.go - Testable example
├── stemmer - Sub module
│   ├── stemmer.go
│   └── stemmer_test.go
├── testdata - Test data
│      └── tokenize_cases.toml - Test cases
└── cmd  - Executables
    └── nlpd - HTTP server
        ├── main.go
        └── main_test.go

Terminal Log

Links

• Configuration
  • envconfig
  • viper & cobra
• Logging
  • Built-in log
  • uber/zap
  • logrus
  • zerolog
• Metrics
  • Built-in expvar
  • Open Telemetry
  • Prometheus
• Go Code Review Comments
• Tutorial: Getting started with multi-module workspaces
• Example Project Structure
• How to Write Go Code
• Documentation
  • Godoc: documenting Go code
  • Testable examples in Go
  • Go documentation tricks
  • gob/doc.go of the gob package. Generates this documentation
  • go install golang.org/x/pkgsite/cmd/pkgsite@9ffe8b928e4fbd3ff7dcf984254629a47f8b6e63 (require go 1.18)
  • pkgsite -http=:8080 (open browser on http://localhost:8080/${module name})
• Out Software Dependency Problem - Good read on dependencies by Russ Cox
• Linters (static analysis)
  • staticcheck
  • gosec - Security oriented
  • golang.org/x/tools/go/analysis - Helpers to write analysis tools (see example)
• Testing
  • testing
  • testify - Many test utilities (including suites & mocking)
  • Tutorial: Getting started with fuzzing
    • testing/quick - Initial fuzzing library
  • test containers
• HTTP Servers
  • net/http
  • net/http/httptest
  • gorilla/mux - HTTP router with more frills
  • chi - A nice web framework

Data & Other

• nlp.go
• stemmer.go
• tokenize_cases.toml
  • github.com/BurntSushi/toml