well, i know...very appreciate for your explaination, thank you very much.
在 2019年10月11日星期五 UTC+8下午12:41:55，Kurtis Rader写道：
>
> Note that other languages, such as Python, have the same behavior as Go
> for the reason mentioned by Ian. If you call Pop() on an empty
> interface/list/etc., and it returns a distinct value for that condition,
> you still have to check that the pop failed. It is better to require the
> caller to do the check before the pop. This means that callers which don't
> do so will randomly fail. Which is a net positive.
>
> On Thu, Oct 10, 2019 at 9:30 PM Ian Lance Taylor <ia...@golang.org
> <javascript:>> wrote:
>
>> On Thu, Oct 10, 2019 at 9:14 PM 陈清和 <chen...@gmail.com <javascript:>>
>> wrote:
>> >
>> > src/container/heap/heap.go:
>> >
>> > ```go
>> > func Pop(h Interface) interface{} {
>> > n := h.Len() - 1
>> > h.Swap(0, n)
>> > down(h, 0, n)
>> > return h.Pop()
>> > }
>> > ```
>> >
>> > While the h is empty, also the h.Len() equals to 0,why not return nil
>> in advance? In the current way, we have to do boundary check in implement
>> of Swap, otherwise there will be panic.
>>
>> This is not really different from the fact that
>>
>> var s []int
>> fmt.Println(s[0])
>>
>> will also panic. Yes, if you don't know how many elements you have,
>> you need to check the length.
>>
>> Ian
>>
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>> .
>>
>
>
> --
> Kurtis Rader
> Caretaker of the exceptional canines Junior and Hank
>
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