Created
July 15, 2020 08:12
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Writer proxy error monad for Golang
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| package wr | |
| import "io" | |
| type Wr struct { | |
| err error | |
| written int64 | |
| w io.Writer | |
| } | |
| func NewWr(w io.Writer) *Wr { | |
| if wr, isWr := w.(*Wr); isWr { | |
| return wr | |
| } | |
| return &Wr{w: w} | |
| } | |
| func (wr *Wr) Write(data []byte) (int, error) { | |
| if wr.Failed() { | |
| return 0, wr.err | |
| } | |
| var n, err = wr.w.Write(data) | |
| wr.err = err | |
| wr.written += int64(n) | |
| return n, err | |
| } | |
| func (wr *Wr) Written() int64 { return wr.written } | |
| func (wr *Wr) Err() error { return wr.err } | |
| func (wr *Wr) Failed() bool { return wr.err != nil } |
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