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46 lines
928 B
Markdown
46 lines
928 B
Markdown
---
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id: 8f08356d-b0dc-465b-b7f5-5522b5133916
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title: Golang Embedding
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---
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# Description
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[Embedding](https://golang.org/doc/effective_go.html#embedding) is Gos
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answer to subclasses. There's one caveat:
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> There's an important way in which embedding differs from subclassing.
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> When we embed a type, the methods of that type become methods of the
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> outer type, but when they are invoked the receiver of the method is
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> the inner type, not the outer one.
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# Interfaces
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``` go
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type Reader interface {
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Read(p []byte) (n int, err error)
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}
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type Writer interface {
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Write(p []byte) (n int, err error)
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}
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type ReadWriter interface {
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Reader
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Writer
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}
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```
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`ReadWriter` "extends" `Reader` & `Writer` in the example above.
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# Structs
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``` go
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type ReadWriter struct {
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*Reader // *bufio.Reader
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*Writer // *bufio.Writer
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}
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func (rw *ReadWriter) Read(p []byte) (n int, err error) {
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return rw.reader.Read(p)
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}
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```
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