Duck! An interface love story

Using interfaces in golang is a lot like duck typing. Find your inner duck with some practical examples.

Transcript

1. Duck! an interface love story
2. @mraaroncruz
3. @mraaroncruz I build prototypes/MVPs to help startups find funding.
4. @mraaroncruz I build prototypes/MVPs to help startups find funding. iOS and Android Native
5. @mraaroncruz I build prototypes/MVPs to help startups find funding. iOS and Android Native Ruby on Anything
6. @mraaroncruz I build prototypes/MVPs to help startups find funding. iOS and Android Native Ruby on Anything Go
7. @mraaroncruz I build prototypes/MVPs to help startups find funding. iOS and Android Native Ruby on Anything Go Elixir?
8. @mraaroncruz I build prototypes/MVPs to help startups find funding. iOS and Android Native Ruby on Anything Go Elixir? Indian Food Chef
9. @mraaroncruz I build prototypes/MVPs to help startups find funding. iOS and Android Native Ruby on Anything Go ROSSConf Team Elixir? Indian Food Chef
10. Go and OOP
11. Things in common
12. Things in common encapsulation (lower/uppercase)
13. Things in common encapsulation (lower/uppercase) this/self from first argument
14. Things in common encapsulation (lower/uppercase) this/self from first argument constructor
15. Things in common encapsulation (lower/uppercase) this/self from first argument constructor methods
16. Things in common encapsulation (lower/uppercase) this/self from first argument constructor methods mixins
17. Things in common encapsulation (lower/uppercase) this/self from first argument constructor methods mixins interfaces
18. Duck Typing
20. Walks like duck
21. Walks like duck Quacks like duck
23. Messages
24. What it does
25. What it does not what it is
26. Benefits of Duck Typing
27. Benefits of Duck Typing Easier to change code
28. Benefits of Duck Typing Easier to change code Testing
29. Benefits of Duck Typing Easier to change code Testing Clearly defined public interfaces
30. Confident Code
31. Tell, don’t ask
32. – Avdi Grimm in Confident Ruby “As confident coders, we want to tell our ducks to quack and then move on”
33. Code Example
34. class Pdf def first_page_to_image puts "rip front page" end def optimize puts "Optimizing pdf for download" end end
35. class Pdf def first_page_to_image puts "rip front page" end def optimize puts "Optimizing pdf for download" end end class Png def resize puts "creating different sizes for png" end end
36. class Pdf def first_page_to_image puts "rip front page" end def optimize puts "Optimizing pdf for download" end end class Png def resize puts "creating different sizes for png" end end class Txt def zip puts "Zipping text file" end end
37. # Set up scene pdf = Pdf.new png = Png.new text = Txt.new documents = [pdf, png, text]
38. # Do some work! documents.each do |doc| case doc when Pdf doc.first_page_to_image doc.optimize when Png doc.resize when Txt doc.zip end end
40. # Duck type it! class Pdf def prepare_download first_page_to_image optimize end end class Png def prepare_download resize end end class Txt def prepare_download zip end end
41. # So much simpler documents.each do |doc| doc.prepare_download end
42. # So much simpler documents.each do |doc| doc.prepare_download end # or a one liner documents.each(&:prepare_download)
43. Go Time!
44. package main import "fmt" type Pdf struct { Body []byte } type Png struct { Versions []struct { Version string Body []byte } } type Txt struct { Body string }
45. func (d *Pdf) RipFirstPage() { fmt.Println("Ripped first page") } func (d *Pdf) Optimize() { fmt.Println("Optimize images in pdf") } func (d *Png) Resize() { fmt.Println("Resized png for download") } func (d *Txt) Zip() { fmt.Println("Zipped text file") }
46. func main() { documents := []interface{}{ &Pdf{}, &Png{}, &Txt{}, } for _, doc := range documents { switch doc.(type) { case *Pdf: pdf := doc.(*Pdf) pdf.RipFirstPage() pdf.Optimize() case *Png: png := doc.(*Png) png.Resize() case *Txt: txt := doc.(*Txt) txt.Zip() } } }
47. func main() { documents := []interface{}{ &Pdf{}, &Png{}, &Txt{}, } for _, doc := range documents { switch doc.(type) { case *Pdf: pdf := doc.(*Pdf) pdf.RipFirstPage() pdf.Optimize() case *Png: png := doc.(*Png) png.Resize() case *Txt: txt := doc.(*Txt) txt.Zip() } } }
48. func main() { documents := []interface{}{ &Pdf{}, &Png{}, &Txt{}, } for _, doc := range documents { switch doc.(type) { case *Pdf: pdf := doc.(*Pdf) pdf.RipFirstPage() pdf.Optimize() case *Png: png := doc.(*Png) png.Resize() case *Txt: txt := doc.(*Txt) txt.Zip() } } }
50. type DownloadPreparer interface { Prepare() } func (d *Pdf) Prepare() { d.RipFirstPage() d.Optimize() } func (d *Png) Prepare() { d.Resize() } func (d *Txt) Prepare() { d.Zip() }
51. type DownloadPreparer interface { Prepare() } func (d *Pdf) Prepare() { d.RipFirstPage() d.Optimize() } func (d *Png) Prepare() { d.Resize() } func (d *Txt) Prepare() { d.Zip() }
52. type DownloadPreparer interface { Prepare() } func (d *Pdf) Prepare() { d.RipFirstPage() d.Optimize() } func (d *Png) Prepare() { d.Resize() } func (d *Txt) Prepare() { d.Zip() }
53. func main() { documents := []DownloadPreparer{ &Pdf{}, &Png{}, &Txt{}, } for _, doc := range documents { doc.Prepare() } }
57. m.shattock on flickr https://flic.kr/p/r6d6sp Ducks in the wild
58. Read Source Code
59. github.com/zquestz/s
60. s -p amazon go gopher doll
64. s -p youtube go versus javascript
66. github.com/wercker/wercker
72. Code Confidently
73. Find your ducks
74. Read source code
75. Thank you @mraaroncruz bit.ly/gophercon-ducks Find slides and awesome videos