ctx = context.TODO()cmd := exec.CommandContext(ctx, <some_cmd>, <some_arg>)fmt.Println(ctx.Err())ctx.Err() 是否會在 ctx 為 context.TODO() 時變為非零？
1 回答
浮云間
TA貢獻1829條經驗 獲得超4個贊
context.TODO().Err() 將始終返回 nil，這在源代碼中很容易看出：
package context
// An emptyCtx is never canceled, has no values, and has no deadline.
type emptyCtx int
func (*emptyCtx) Err() error {
return nil
}
// ...
var (
todo = new(emptyCtx)
)
// ...
// TODO returns a non-nil, empty Context. Code should use context.TODO when
// it's unclear which Context to use or it is not yet available (because the
// surrounding function has not yet been extended to accept a Context
// parameter).
func TODO() Context {
return todo
}
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