Go 101

Introduction to Go in Shopa

Transcript

1. Go 101 Shopa workshop day, August 2015 Álex González
2. Some history Designed by: Robert Griesemer, Rob Pike & Ken Thompson 6 years ago At Google To improve C++ And because they hated it
3. Why Go? Asynchronous concurrency as part of the language Compiled to a single binary Garbage collected Fast Go tools!
4. Why NOT Go? Libraries not always as mature, but improving! No generics... is that a real problem? Dependency management
5. Your first program p a c k a g e m a i n i m p o r t " f m t " f u n c m a i n ( ) { f m t . P r i n t l n ( " H i w o r l d ! " ) } Run
6. Hands on!
7. types { u , } i n t { , 8 , 1 6 , 3 2 , 6 4 } f l o a t { 3 2 , 6 4 } c o m p l e x { 6 4 , 1 2 8 } b o o l b y t e r u n e "Code point" in Unicode (item represented by a single value). s t r i n g
8. More types a r r a y s An array type definition specifies a length and an element type. s l i c e s A slice is a data structure describing a contiguous section of an array stored separately from the slice variable itself. A slice is not an array. A slice describes a piece of an array. m a p s Key/value storage.
9. Moarrrrr types s t r u c t s p o i n t e r s f u n c t i o n s i n t e r f a c e s t y p e S h o p a s t r u c t { e m p l o y e e s i n t } f u n c m a i n ( ) { s : = S h o p a { e m p l o y e e s : 2 , } f m t . P r i n t l n ( s . e m p l o y e e s ) } Run
10. THE Type c h a n "A channel can be imagined to be a pipe or a conveyer belt of a defined size and capacity. On one side one can place an item onto this imaginary conveyer belt and on the other side one can take it."
11. Let's the magic begin
12. Named errors v a r N a m e d E r r o r = e r r o r s . N e w ( " I s t h i s a n e x c e p t i o n ? " ) f u n c b r e a k S o m e t h i n g ( ) e r r o r { r e t u r n N a m e d E r r o r } f u n c m a i n ( ) { e r r : = b r e a k S o m e t h i n g ( ) s w i t c h e r r { c a s e N a m e d E r r o r : l o g . P r i n t l n ( " F a i l e d a s e x p e c t e d " ) d e f a u l t : l o g . P a n i c ( " I d i d n ' t e x p e c t t h i s ! " ) } i f e r r : = b r e a k S o m e t h i n g ( ) ; e r r = = N a m e d E r r o r { l o g . P r i n t l n ( " T h i s f a i l e d a s e x p e c t e d a s w e l l ! " ) } } Run
13. JSON t y p e P e r s o n s t r u c t { N a m e s t r i n g } f u n c m a i n ( ) { p a y l o a d : = [ ] b y t e ( ` [ { " n a m e " : " A l e x " } , { " n a m e " : " N i c o l a " } ] ` ) v a r p e o p l e [ ] P e r s o n i f e r r : = j s o n . U n m a r s h a l ( p a y l o a d , & p e o p l e ) ; e r r ! = n i l { l o g . P a n i c ( e r r ) / / D o n ' t d o t h i s a t h o m e } f o r _ , p : = r a n g e p e o p l e { f m t . P r i n t l n ( p . N a m e ) } } Run
14. Type switch f u n c o u t p u t ( w h a t e v e r i n t e r f a c e { } ) { s w i t c h v : = w h a t e v e r . ( t y p e ) { c a s e s t r i n g : f m t . P r i n t l n ( " A S t r i n g : " , v ) c a s e i n t : f m t . P r i n t l n ( " S o m e i n t : " , v ) d e f a u l t : f m t . P r i n t l n ( " I d o n ' t k n o w w h a t t y p e i s t h i s o n e : " , v ) } } f u n c m a i n ( ) { o u t p u t ( " t h i s i s s o m e t e x t " ) o u t p u t ( 1 ) o u t p u t ( 1 . 1 ) } Run
15. The good one about interfaces! t y p e S h o p e r i n t e r f a c e { L i k e s F a s h i o n ( ) b o o l } t y p e ( C a r S h o p e r s t r u c t { } S h o e S h o p e r s t r u c t { } ) f u n c ( s C a r S h o p e r ) L i k e s F a s h i o n ( ) b o o l { r e t u r n f a l s e } f u n c ( s S h o e S h o p e r ) L i k e s F a s h i o n ( ) b o o l { r e t u r n t r u e } f u n c I s P o s s i b l e S h o p a C l i e n t ( s S h o p e r ) b o o l { r e t u r n s . L i k e s F a s h i o n ( ) } f u n c m a i n ( ) { f m t . P r i n t l n ( I s P o s s i b l e S h o p a C l i e n t ( C a r S h o p e r { } ) , I s P o s s i b l e S h o p a C l i e n t ( S h o e S h o p e r { } ) ) } Run
17. Concurrency f u n c m a i n ( ) { f o r i : = 0 ; i < 1 0 ; i + + { g o f m t . P r i n t l n ( i ) } / / S o m e t h i n g i s g o i n g t o g o w r o n g . . . } Run
18. ... patterns f u n c d o i t ( i i n t , d o n e c h a n b o o l ) { t i m e . S l e e p ( t i m e . D u r a t i o n ( r a n d . I n t n ( 3 ) ) * t i m e . S e c o n d ) f m t . P r i n t l n ( i ) d o n e < - t r u e } f u n c m a i n ( ) { d o n e : = m a k e ( c h a n b o o l , 1 ) f o r i : = 0 ; i < 1 0 ; i + + { g o d o i t ( i , d o n e ) } f o r i : = 0 ; i < 1 0 ; i + + { < - d o n e } } Run
19. ... and more patterns f u n c m a i n ( ) { v a r w g s y n c . W a i t G r o u p f o r i : = 0 ; i < 1 0 ; i + + { w g . A d d ( 1 ) g o f u n c ( i i n t ) { f m t . P r i n t l n ( i ) w g . D o n e ( ) } ( i ) } w g . W a i t ( ) } Run
20. OMG
21. Channels f u n c f i l l ( q u e u e c h a n < - P e r s o n , w g * s y n c . W a i t G r o u p ) { d e f e r c l o s e ( q u e u e ) d e f e r w g . D o n e ( ) f o r _ , n a m e : = r a n g e [ ] s t r i n g { " A l e x " , " N i c o l a " , " G e o r g e " , " A n t h o n y " , " S a m " } { q u e u e < - P e r s o n { n a m e } t i m e . S l e e p ( t i m e . D u r a t i o n ( r a n d . I n t n ( 1 0 0 0 ) ) * t i m e . M i l l i s e c o n d ) } } f u n c v i s i t ( q u e u e < - c h a n P e r s o n , w g * s y n c . W a i t G r o u p ) { d e f e r w g . D o n e ( ) f o r p : = r a n g e q u e u e { f m t . P r i n t l n ( p . N a m e , " i s v i s i t i n g " ) } } f u n c m a i n ( ) { q u e u e : = m a k e ( c h a n P e r s o n , 2 ) / / . . . Run
22. Your own server v a r ( c o u n t e r i n t p o r t = 9 0 0 0 ) f u n c c o u n t ( w h t t p . R e s p o n s e W r i t e r , r * h t t p . R e q u e s t ) { c o u n t e r + + } f u n c s t a t s ( w h t t p . R e s p o n s e W r i t e r , r * h t t p . R e q u e s t ) { w . W r i t e ( [ ] b y t e ( f m t . S p r i n t f ( " V i s i t s : % d " , c o u n t e r ) ) ) } f u n c m a i n ( ) { / / h t t p . H a n d l e F u n c ( " / f a v i c o n . i c o " , f u n c ( _ h t t p . R e s p o n s e W r i t e r , _ * h t t p . R e q u e s t ) { } ) h t t p . H a n d l e F u n c ( " / " , c o u n t ) h t t p . H a n d l e F u n c ( " / s t a t s " , s t a t s ) l o g . P r i n t l n ( " L i s t e n i n g a t p o r t " , p o r t ) l o g . P a n i c ( h t t p . L i s t e n A n d S e r v e ( f m t . S p r i n t f ( " : % d " , p o r t ) , n i l ) ) } Run
23. Thank you Álex González agonzalezro@gmail.com (mailto:agonzalezro@gmail.com) http://agonzalezro.github.io (http://agonzalezro.github.io) @agonzalezro (http://twitter.com/agonzalezro)