understanding the interface

1 .understanding the interface @francesc 

2 .what is an interface? 

3 ."In object-oriented programming, a protocol or interface is a common means for unrelated objects to communicate with each other" - wikipedia 

4 ."In object-oriented programming, a protocol or interface is a common means for unrelated objects to communicate with each other" - wikipedia 

5 ."In object-oriented programming, a protocol or interface is a common means for unrelated objects to communicate with each other" - wikipedia 

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9 .what is a Go interface? 

10 .abstract types concrete types 

11 .concrete types in Go - they describe a memory layout int8 int16 int32 int64 - behavior attached to data through methods 

12 . *gzip.Writer *strings.Reader []bool int *os.File 

13 .abstract types in Go - they describe behavior io.Reader io.Writer fmt.Stringer - they define a set of methods, without specifying the receiver 

14 .two interfaces 

15 . io.Writer *gzip.Writer *strings.Reader []bool io.Reader int *os.File 

16 .union of interfaces 

17 .union of interfaces 

18 . io.Writer *gzip.Writer *strings.Reader []bool io.Reader int *os.File io.ReadWriter 

19 . ? io.Writer *gzip.Writer *strings.Reader []bool io.Reader int *os.File io.ReadWriter 

20 .interface{} 

21 .“interface{} says nothing” - Rob Pike in his Go Proverbs 

22 .

23 .why do we use interfaces? 

24 .why do we use interfaces? - writing generic algorithms - hiding implementation details - providing interception points 

25 .what function do you prefer? 

26 .Cons: how would you test it? what if you want to write to memory? Pros: ? 

27 .Cons: how do you even write to interface{}? probably requires runtime checks Pros: you can write really bad code 

28 .Which ones does WriteTo really need? - Write - Read - Close 

29 .“The bigger the interface, the weaker the abstraction” - Rob Pike in his Go Proverbs