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go-tchas.slide
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Go-tchas
Go Cracow Meetup #10
17 Oct 2023
Tags: go, golang, gotchas, mistakes, problems
Summary: An overview of Go gotchas we all get caught by from time to time.
Piotr Luciński
Principal Engineer, Splunk
https://linkedin.com/in/piotr-lucinski
https://github.com/lootek
* recording
A recording of this talk is available [[https://www.youtube.com/watch?v=6b7Y14XAMXY][here]]
.image ./go-tchas/yt.png _ 600
* about me
Go enthusiast since 2013
a C++ freak before
trying to forget JavaScript
becoming a DevSecOps
.image ./go-tchas/gopher.png _ 300
* how to start with Go
.link https://go.dev/tour/welcome/1 A Tour of Go
.link https://go.dev/doc/ Documentation - The Go Programming Language
.link https://go.dev/doc/effective_go Effective Go - The Go Programming Language
.link https://github.com/golang/go/wiki/CodeReviewComments CodeReviewComments
.link https://tip.golang.org/doc/faq Go FAQ
.link https://go101.org/article/101.html Go101
.link https://go.dev/play/ The Go Playground
* everything is a copy
- no references!
* methods, receivers
.play go-tchas/receivers.go /^// START/,/^// END/
* methods, receivers (ctd)
.play go-tchas/receivers-2.go /^// START/,/^// END/
* slices
.image go-tchas/slice.png _ 400
.caption Source: [[https://dave.cheney.net/2018/07/12/slices-from-the-ground-up][Dave Cheney - Slices from the ground up]]
* slices (ctd: init)
s := make([]byte, 5)
.image go-tchas/slice-1.png _ 600
.caption Source: [[https://go.dev/blog/slices-intro][The Go Blog - Go Slices: usage and internals]]
* slices (ctd: reslicing)
s = s[2:4]
.image go-tchas/slice-2.png _ 600
.caption Source: [[https://go.dev/blog/slices-intro][The Go Blog - Go Slices: usage and internals]]
* slices (ctd: leak)
.code go-tchas/slices-digits-leak.go /^// START/,/^// END/
* slices (ctd: growing)
.play go-tchas/slices-append.go /^// START/,/^// END/
* slices (ctd: appending)
.code go-tchas/slices-append-2.go /^// START/,/^// END/
* slices (ctd: appending)
.play go-tchas/slices-append-2-prints.go /^// START/,/^// END/
* maps
.image go-tchas/maps1.jpg _ 400
.image go-tchas/maps2.png _ 400
.caption Source: [[https://www.youtube.com/watch?v=Tl7mi9QmLns][Keith Randall - Inside the Map Implementation]]
* channels vs. mutexes
- mutex -> accessing shared data
- channels -> communication between goroutines, transferring ownership
* channels (state)
.image go-tchas/86_state.png _ 800
.caption Source: [[https://www.ardanlabs.com/blog/2017/10/the-behavior-of-channels.html][ArdanLabs - The Behavior Of Channels]]
* channels (delivery)
.image go-tchas/86_guarantee_of_delivery.png _ 800
.caption Source: [[https://www.ardanlabs.com/blog/2017/10/the-behavior-of-channels.html][ArdanLabs - The Behavior Of Channels]]
* channels (signaling)
.image go-tchas/86_signaling_with_data.png _ 800
.image go-tchas/86_signaling_without_data.png _ 800
.caption Source: [[https://www.ardanlabs.com/blog/2017/10/the-behavior-of-channels.html][ArdanLabs - The Behavior Of Channels]]
* marshal
.play go-tchas/marshal.go /^// START/,/^// END/
.caption [[https://go.dev/play/p/-cgWn3NKo0T]]
* strings (iterating)
.play go-tchas/strings.go /^// START/,/^// END/
* strings (performance)
.code go-tchas/strings-append.go /^// START/,/^// END/
* shadowing
.code go-tchas/errors-shadowing.go /^// START/,/^// END/
* shadowing (ctd)
.play go-tchas/true-or-false.go
* errors handling
.code go-tchas/errors-aggregation.go /^// START/,/^// END/
* timer leak
.play go-tchas/timer.go /^// START/,/^// END/
* timer leak fixed
.play go-tchas/timer-2.go /^// START/,/^// END/
* panic
.play go-tchas/panic.go /^// START/,/^// END/
* panic (ctd)
.play go-tchas/panic-2.go /^// START/,/^// END/
* for loop
.play go-tchas/for-loop-0.go /^// START/,/^// END/
.play go-tchas/for-loop.go /^// START/,/^// END/
.play go-tchas/for-loop-2.go /^// START/,/^// END/
.play go-tchas/for-loop-3.go /^// START/,/^// END/
* interfaces
.play go-tchas/interfaces.go /^// START/,/^// END/
* interfaces (ctd)
.play go-tchas/interfaces-2.go /^// START/,/^// END/
* interfaces (ctd)
.play go-tchas/interfaces-3.go /^// START/,/^// END/
* defer (order)
.play go-tchas/defer-stack.go /^// START/,/^// END/
* defer (ctd: scope)
.code go-tchas/defer-loop.go /^// START/,/^// END/
* defer (ctd: named return params)
.play go-tchas/defer-error.go /^// START/,/^// END/
* defer (ctd: named return params fixed)
.play go-tchas/defer-error-fix.go /^// START/,/^// END/
* files naming
- Directory and file names that begin with `.` or `_` are ignored
- directories named `testdata` are ignored
- file names ending in `_test.go` are tests
* files naming (build tags)
- file header:
//go:build linux
// +build linux
- or file name:
server_linux.go
* files naming (build tags)
- file header:
//go:build !windows
// +build !windows
- and telling file name:
server_other.go
* low-hanging fruits
- unit tests
- race detector
- pprof
* linters
.link https://golangci-lint.run/usage/linters/ golangci-lint
.link https://vuln.go.dev/ govulncheck
* continuous learning
.link https://golangweekly.com/ Golang Weekly
.link https://tip.golang.org/blog/ The Go Blog
.link https://changelog.com/gotime The Go Time podcast
*
.image ./go-tchas/qr.png _ 500
.caption [[https://go-talks.appspot.com/github.com/lootek/talks/go-tchas.slide]]