-
Notifications
You must be signed in to change notification settings - Fork 6
/
00_prelude.slide
263 lines (146 loc) · 12.2 KB
/
00_prelude.slide
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
Introduction to Go
0 - Prelude
Julien Cretel
https://jub0bs.com
@jub0bs.bsky.social
https://infosec.exchange/@jub0bs
* About this slidedeck
*Licence*
These slides are freely available at [[https://github.com/jub0bs/go-course-beginner]] and are subject to a [[https://creativecommons.org/licenses/by-nc-sa/3.0/][CC BY-NC-SA 4.0 licence]].
*Why*English*rather*than*French?*
The French terminology about Go concepts isn't firmly established yet; for instance, some people translate _slice_ (which is a Go data structure) to _coupe_ and others to _tranche_.
Moreover, most of the Go learning resources available online are in English.
*How*to*run*these*slides*locally*
[[https://github.com/jub0bs/go-course-beginner/blob/main/README.md][The README]] constains instructions for running the slides with [[https://pkg.go.dev/golang.org/x/tools/cmd/present][a Go-specific tool]].
Some of these slides contain editable and executable code snippets. If you need to add a line break somewhere in a code snippet, make sure [[https://github.com/golang/go/issues/9011][to type Shift + Enter]].
* About me
- known as @jub0bs on the Web
- self-employed since 2019
- Go developer since 2017
- Web-security researcher & consultant
- occasional bug-bounty hunter
- trainer on topics such as [[https://www.humancoders.com/formations/go][Go]] and [[https://www.humancoders.com/formations/securite-des-applications-web][Web security]]
- blogger (at [[https://jub0bs.com][jub0bs.com]])
.image https://habrastorage.org/getpro/habr/post_images/eb1/923/9cc/eb19239cc91d38445932da1ade5a5e7d.png 200 _
: pentests, vulnerability evaluation, code audits
: introduce yourselves to the other participants in 60 seconds or less
* Setup
If you haven't already, install Go by following the guidance from [[https://go.dev/dl]].
You can check which version of Go is installed by running the following shell command:
$ go version
go version go1.22.4 darwin/amd64
To cut your teeth on Go, I recommend [[https://code.visualstudio.com/][Visual Studio Code]] and its [[https://marketplace.visualstudio.com/items?itemName=golang.Go][Go extension]], which embarks a number of utilities such as `goimports` and `gofmt`.
Also, make sure you have Git installed.
* Rough course outline & expected difficulty curve
.image img/difficulty_vs_time.svg 400 _
: https://excalidraw.com/#json=m8YUv7D6vovgtROSA0AnH,zc9t16WYwXH_FDftsmming
* Namecheck project
You'll develop a small command-line tool (and later a HTTP API) for checking the *validity* and *availability* of a username on multiple social networks: GitHub, etc.
Over the years, I have found this project to be a good forcing function for learning Go.
Moreover, there is a [[https://twitter.com/marckohlbrugge/status/1682064001331609615][business case]] for such a tool, as it would allow organizations and even individuals to choose a brand name consistent across multiple platforms.
: see Poppulo's case on X/Twitter: https://twitter.com/poppulo
.image https://go.dev/blog/gophergala/fancygopher.jpg 200 _
Besides, if you're 😈, you may find this tool useful for [[https://en.wikipedia.org/wiki/Cybersquatting#Social_media][name squatting]]. Be aware that this practice is [[https://docs.github.com/en/site-policy/other-site-policies/github-username-policy][prohibited by GitHub]] and most of the other social networks, though.
: discover a coveted username that's available on some platform, claim it for yourself and later sell it to an interested party
* Genesis of the language
Go was created in 2007 at Google by
- *Robert*Griesemer* (worked on [[https://en.wikipedia.org/wiki/V8_(JavaScript_engine)][V8]] and [[https://en.wikipedia.org/wiki/HotSpot_(virtual_machine)][the HotSpot JVM]], studied with [[https://en.wikipedia.org/wiki/Niklaus_Wirth][Niklaus Wirth]]),
- *Rob*Pike* (worked on [[https://en.wikipedia.org/wiki/Plan_9_from_Bell_Labs][Plan 9]], [[https://en.wikipedia.org/wiki/UTF-8][UTF-8]], and experimental predecessors to Go), and
- *Ken*Thompson* (worked on [[https://en.wikipedia.org/wiki/Unix][Unix]], [[https://en.wikipedia.org/wiki/Plan_9_from_Bell_Labs][Plan 9]], [[https://en.wikipedia.org/wiki/UTF-8][UTF-8]], [[https://en.wikipedia.org/wiki/Turing_Award][Turing Award]] recipient)
.image https://miro.medium.com/max/1256/0*pCC5UI7QqThjdBvm.png _ 600
: Thompson: first implementor of regexps
: Pike/Thompson: former Bell Labs employees
: Pike: predecessor languages to Go (Newsqueak, Alef, Limbo)
: Thompson: invented increment/decrement operators; see https://en.wikipedia.org/wiki/B_(programming_language)#History
: Pike/Griesemer: worked on Sawzall at Google
* Genesis of the language (cont'd)
Back in 2007, [[https://www.youtube.com/watch?v=sln-gJaURzk&t=17m47s][C++'s increasing complexity]], [[https://www.youtube.com/watch?v=i0zzChzk8KE&t=545s][slow compilation]], and [[https://www.youtube.com/watch?v=iTrP_EmGNmw&t=18m30s][poor support for concurrency]] were [[https://www.youtube.com/watch?v=iTrP_EmGNmw&t=18m30s][recurring sources of frustration]] for the three creators of Go, where C++ is heavily used for infrastructure.
.image https://imgs.xkcd.com/comics/compiling.png 180 _
They enlisted the help of Ken Thompson and started working on a new language, which ultimately became Go... For more on the origins of Go, see
- [[https://www.youtube.com/watch?v=YXV7sa4oM4I][Rob Pike - The Go Programming Language and Environment]]
- [[https://www.youtube.com/watch?v=6oF0UblqkGs&t=465s][Carmen Andoh - 10 Years of Go (GopherConAU 2019)]]
- [[https://www.youtube.com/watch?v=igFz-5rdn2Y&t=85s][Cameron Balahan - Keynote: The State Of Go (GopherCon Europe 2023)]].
: for Google's infrastructure code: https://www.youtube.com/watch?v=rFejpH_tAHM&t=10m42s
* A brief history of Go
- 2007: Griesemer, Pike & Thompson start working on Go.
- 2008: Ian Lance Taylor & Russ Cox (both from Google) join the Go team.
- 2009: Go is open-sourced.
- 2012: [[https://go.dev/blog/go1][Go 1.0 is released]]. [[https://go.dev/doc/go1compat][The language becomes stable.]] [[https://www.youtube.com/watch?v=iTrP_EmGNmw&t=34m15s][Adoption rises sharply.]]
- 2013: Docker
- 2014: Kubernetes; first GopherCon conference
- 2015: The go compiler (`gc`) becomes [[https://en.wikipedia.org/wiki/Self-hosting_(compilers)][self-hosted]].
- 2022: Go 1.18 adds generics to the language.
- 2024: Go 1.22 (the latest minor version) is released.
: Russ and ILT joined the Go Team
: - between 2007 and 2009: https://research.swtch.com/back
: - 2008! https://www.youtube.com/watch?v=0Zbh_vmAKvk&t=10s
* Logo & mascot
Go's logo may strike you as rather uninspired and unremarkable:
.image https://go.dev/blog/go-brand/logos.jpg 150 _
However, [[https://go.dev/blog/gopher][Go's mascot]], a [[https://en.wikipedia.org/wiki/Gopher][gopher]], enjoys worldwide recognition:
.image https://go.dev/blog/gopher/gopher.png 150 _
In fact, Go programmers are affectionately known as "Gophers".
: Lapins Crétins vibe!
* What kind of language is Go?
: Although Go has its roots in C, it is in many ways a more powerful language.
*Concurrent*programming*
Go's [[https://en.wikipedia.org/wiki/Concurrent_computing][concurrency]] features let you cleanly delineate independent tasks in your code.
*Object*orientation*
The ability to define custom types (and methods on them) promote [[https://en.wikipedia.org/wiki/Abstraction_(computer_science)#Abstraction_in_object_oriented_programming][_abstraction_]].
Go's interfaces (and generics) enable [[https://en.wikipedia.org/wiki/Polymorphism_(computer_science)][_polymorphism_]].
Go's packages enable [[https://en.wikipedia.org/wiki/Encapsulation_(computer_programming)][_encapsulation_]].
Go has no concept of [[https://en.wikipedia.org/wiki/Inheritance_(object-oriented_programming)][_inheritance_]], but facilitates [[https://en.wikipedia.org/wiki/Object_composition][_composition_]] instead. For more on the topic, see [[https://go.dev/doc/faq#Is_Go_an_object-oriented_language][Is Go an object-oriented language? (FAQ)]]
*Functional*aspects*
Go supports [[https://en.wikipedia.org/wiki/First-class_function][first-class functions]], multiple function results, [[https://en.wikipedia.org/wiki/Recursion#In_computer_science][recursion]], and [[https://en.wikipedia.org/wiki/Closure_(computer_programming)][closures]].
: Can a language without inheritance be described as object-oriented? Sure!
: [[https://www.infoworld.com/article/2073649/why-extends-is-evil.html][Allen Holub - Why extends is evil (InfoWorld 2003)]]
: [[https://www.quora.com/What-does-Alan-Kay-think-about-inheritance-in-object-oriented-programming][What does Alan Kay think about inheritance in object-oriented programming? (Quora)]]
: James Gosling (Java): "I'd leave classes out."
: No concept of inheritance in Alan Kay's Simula... a Web of objects
: no classes
: no constructors
: no operator overloading
: no method overloading
: subtyping, but no covariance/contravariance
: encapsulation at the package level rather than at the type/class level
: packages: no ifdef guards, no required ordering of package-level declarations, encapsulation
: Brian Kernighan (popularized C): I think that the real problem with C is that it doesn't give you enough mechanisms for structuring really big programs, for creating ``firewalls'' within programs so you can keep the various pieces apart. https://www.cs.cmu.edu/~mihaib/kernighan-interview/
* Go's rich toolchain
- [[https://pkg.go.dev/cmd/go][cross-compilation]]
- [[https://pkg.go.dev/cmd/gofmt][code formatting]] & [[https://pkg.go.dev/golang.org/x/tools/cmd/goimports][automatic package imports]]
- [[https://pkg.go.dev/golang.org/x/pkgsite/cmd/pkgsite][documentation generation]]
- [[https://pkg.go.dev/testing][testing]] & [[https://pkg.go.dev/cmd/cover][code coverage]]
- [[https://pkg.go.dev/cmd/pprof][profiling]] & [[https://pkg.go.dev/cmd/trace][tracing]]
- [[https://go.dev/doc/articles/race_detector][race detector]]
- extensive [[https://pkg.go.dev/std][standard library]]
.image https://habrastorage.org/getpro/habr/post_images/eb1/923/9cc/eb19239cc91d38445932da1ade5a5e7d.png 200 _
: typically run on save
: gofmt: enforced specific style. flattens learning curve and reduces friction for code reviews
: goimports: imports in canonical order and in alphabetical order per section
* Go development pays well
See the results of the Stack Overflow developer survey ([[https://survey.stackoverflow.co/2023/#top-paying-technologies][2023]], [[https://survey.stackoverflow.co/2022/#technology-top-paying-technologies][2022]], [[https://insights.stackoverflow.com/survey/2021#technology-top-paying-technologies][2021]], [[https://insights.stackoverflow.com/survey/2020#technology-what-languages-are-associated-with-the-highest-salaries-worldwide-global][2020]]).
Even if don't stay at your current job for much longer, learning Go is not a waste of time!
: https://insights.stackoverflow.com/survey/2021#technology-top-paying-technologies
.image https://go.dev/blog/gophergala/fancygopher.jpg 300 _
* The Go Playground
The Go Playground (available at [[https://go.dev/play]]) is a Web app that lets you write and run
a small Go program from your browser. Features include:
- code formatting & automatic package imports
- basic static analysis
- [[https://go.dev/play/p/lEDjyvhttIB][limited support for modules and multiple packages]]
- persistent URLs (e.g. [[https://go.dev/play/p/S8HfNUCy13U][https://go.dev/play/p/S8HfNUCy13U]])
- raw program source (^S or ⌘+S)
: static analysis: go vet
: permalinks: convenient for sharing code snippets
.image https://raw.githubusercontent.com/egonelbre/gophers/master/vector/computer/gamer.svg 150 _
: It's a good place to experiment and fix ideas about the language and its standard library.
* Some limitations of the Go Playground
As its name suggests, the Go Playground isn't meant for projects. Limitations include:
- single executable
- no networking (no HTTP requests, etc.)
- no way of specifying command-line arguments
- limited support for third-party packages
.image https://miro.medium.com/max/4800/1*OxWM0qyTBnb6WfSEw-T9sg.jpeg 200 _
: In this course, we'll only use the Playground to solve simple exercises.
: An alternative with more features, incl. syntax highlighting: https://goplay.space/
: support for 3rd-party libraries added in May 2019: https://www.youtube.com/watch?v=6oF0UblqkGs&t=36m50s