pp and reflect

Go Conference 2015 summer

Transcript

1. pp and reflect Go Conference 2015 summer Takashi Kokubun
2. Who is k0kubun? • Twitter, GitHub: @k0kubun • Cookpad • Rubyist
3. k0kubun/pp Colored Pretty Printer https://github.com/k0kubun/pp
4. k0kubun/pp • Prettily print any complex data structures • Simple APIs like “fmt” import "github.com/k0kubun/pp" for _, tweet := range tweets { pp.Println(tweet) }
5. k0kubun/pp • Prettily print any complex data structures • Simple APIs like “fmt”
6. k0kubun/pp ͷෆศͳॴ • ᶃ import͢ΔURL͕ࢥ͍ग़ͤͳ͍ • ᶄ import͠௚͢ͷ͕ΊΜͲ͍͘͞
7. import͢ΔURL͕ࢥ͍ग़ͤͳ͍ Ϣʔβʔͷෆຬᶃ
8. import͢ΔURL͕ࢥ͍ग़ͤͳ͍ import "github.com/◦◦◦/pp" ↑ ͜ͷਓ୭͚ͩͬ…
9. import͢ΔURL͕ࢥ͍ग़ͤͳ͍ ppͷcontributorͷํ
10. import͢ΔURL͕ࢥ͍ग़ͤͳ͍ ձࣾͷઌഐ ͍͍ͪͪιʔείʔυʹ k0kubun͞Μͷ໊લॻ͖ͨ͘ͳ͍Ͱ͢Ͷ…
11. go-pp/ppͱ͍͏forkΛimport import “github.com/go-pp/pp" or import “gopkg.in/pp.v2” ղܾํ๏ɿ
12. import͠௚͢ͷ͕ΊΜͲ͍͘͞ Ϣʔβʔͷෆຬᶄ
13. import͠௚͢ͷ͕ΊΜͲ͍͘͞ import "github.com/k0kubun/pp" ↑ pp.Println() Λॻ͍ͨΓফͨ͠Γ͢ Δͨͼʹ௥Ճ͠௚͢ඞཁ͕͋Δ
14. ؔ਺Λϥοϓͯ͠gitignore import p "github.com/k0kubun/pp" func pp(a ...interface{}) { p.Println(a...) } • ʮ,*ʯΛgitignoreͯ͠ΔͳΒʮ,.goʯͱ͔ • ࢖ͬͯͳͯ͘΋importফ͞ͳͯ͘ࡁΉ ղܾํ๏ɿ
15. package “reflect” Standard library for reflection k0kubun/pp is powered by “reflect”
16. What’s the usage of reflect? • ஋ͷϝλ৘ใΛಡΉ • ppͩͱstructͷશfieldྻڍ • encoding/jsonͩͱstructͷfieldͷλά • ϝλϓϩάϥϛϯά
17. ϝλϓϩάϥϛϯάͷಛ௃ • εϚʔτͳॻ͖ํͰίʔυͷߦ਺ΛݮΒͤΔ • ॻָ͍͍ͯͯ͠ • ੩తղੳ͕೉͘͠ɺಡΈʹ͘͘ͳΔ • झຯҎ֎Ͱ࢖Θͳ͍ͷ͕ແ೉
18. reflectͰͰ͖Δͷ͸࣍ͷ͏ͪͲΕʁ Go ϝλϓϩάϥϛϯάΫΠζ
19. reflectͰͰ͖Δͷ͸࣍ͷ͏ͪͲΕʁ ૢ࡞ ճ౴ ؔ਺ఆٛ ؔ਺ݺͼग़͠ ϝιουఆٛ ϝιουݺͼग़͠ ೚ҙͷܕͷOFX ˕ɿstringͰ໊લΛࢦఆՄɹ˓ɿreflect.Value͔ΒՄೳɹ×ɿແཧ ˕ɺ˓ɺ× ώϯτ: Ruby͸શ෦˕
20. reflectͰͰ͖Δͷ͸࣍ͷ͏ͪͲΕʁ ૢ࡞ ճ౴ ؔ਺ఆٛ ˓ ؔ਺ݺͼग़͠ ˓ ϝιουఆٛ º ϝιουݺͼग़͠ ˕ ೚ҙͷܕͷOFX ˓ ˕ɿstringͰ໊લΛࢦఆՄɹ˓ɿreflect.Value͔ΒՄೳɹ×ɿແཧ ϝλϓϩՄ
21. reflectʹΑΔؔ਺ఆٛ • ೚ҙͷγάωνϟͷؔ਺Λ࡞ΕΔ var f func(int, int) int v := reflect.MakeFunc( reflect.TypeOf(f), func(in []reflect.Value) []reflect.Value { return []reflect.Value{in[0]} }, ) reflect.ValueOf(&f).Elem().Set(v)
22. reflectʹΑΔؔ਺ݺͼग़͠ • ೚ҙͷγάωνϟͷؔ਺Λݺͼग़ͤΔ f := func(a int, b int) int { return a + b } v := reflect.ValueOf(f) in := []reflect.Value{} for i := 0; i < v.Type().NumIn(); i++ { in = append(in, reflect.ValueOf(1)) } v.Call(in)
23. reflectʹΑΔϝιουఆٛ • ී௨ʹແཧ
24. reflectʹΑΔϝιουݺͼग़͠ • stringͰ໊લΛࢦఆͯ͠ϝιουΛݺͼग़ͤΔ type Hoge struct{} func (h Hoge) Foo() { print("foo") } func (h Hoge) Bar() { print("bar") } h := new(Hoge) for _, name := range []string{"Foo", "Bar"} { v := reflect.ValueOf(h) v.MethodByName(name).Call([]reflect.Value{}) }
25. reflectʹΑΔnew • ೚ҙͷܕͷ஋ΛॳظԽͨ͠΋ͷΛ࡞ΕΔ t := reflect.TypeOf(a) reflect.New(t)
26. ·ͱΊ • k0kubun/pp࢖ͬͯԼ͍͞ • pp.Println() Λϥοϓͯ͠gitignore͓ͯ͘͠ • reflect࢖͏ͱϝλϓϩͰ͖Δ • stringͰࢦఆͰ͖Δͷ͸ϝιουݺͼग़͠ͷΈ