为什么iostream哨兵对象在标准中被称为“cerberos”？(Why are iostream sentry objects called “cerberos” in the standard?)

为什么iostream哨兵对象在标准中被称为“cerberos”？(Why are iostream sentry objects called “cerberos” in the standard?)

我想知道__cerb在g++的libstdc++的含义，我发现这似乎是官方C ++标准文档中命名的cerberos的简称。

§22..1 / ：

[示例：iostream operator<<可以实现为：

template <class charT, class traits> basic_ostream<charT,traits>& operator<< (basic_ostream<charT,traits>& s, Date d) { // !!!!!!!!!! typename basic_ostream<charT,traits>::sentry cerberos(s); // <--- !! HERE !! // !!!!!!!!!! if (cerberos) { ios_base::iostate err = ios_base::iostate::goodbit; tm tmbuf; (tmbuf); use_facet<time_put<charT,ostreambuf_iterator<charT,traits> > >( s.getloc()).put(s, s, s.fill(), err, &tmbuf, ’x’); s.setstate(err); // might throw } return s; }

- 结束示例]

为什么iostream sentry对象叫做cerberos ， cerberos究竟意味着什么？

I was wondering what __cerb means in the libstdc++ of g++, and I found out that this seems to be a short name for cerberos as named in the official C++ standard document.

§ 22..1 / :

[ Example: An iostream operator<< might be implemented as:

template <class charT, class traits> basic_ostream<charT,traits>& operator<< (basic_ostream<charT,traits>& s, Date d) { // !!!!!!!!!! typename basic_ostream<charT,traits>::sentry cerberos(s); // <--- !! HERE !! // !!!!!!!!!! if (cerberos) { ios_base::iostate err = ios_base::iostate::goodbit; tm tmbuf; (tmbuf); use_facet<time_put<charT,ostreambuf_iterator<charT,traits> > >( s.getloc()).put(s, s, s.fill(), err, &tmbuf, ’x’); s.setstate(err); // might throw } return s; }

— end example ]

Why are iostream sentry objects called cerberos, and what does cerberos actually mean?

最满意答案

塞伯鲁斯是三头狗¹ ，守护着地狱的大门 ，让那些被困在内部的人避开冥河。 无论是谁写的那部分都喜欢希腊和/或罗马神话，并决定它将是一个适用于当地可变哨兵的名称。

至于为什么它以os结尾，可以想象三种情况：

他们完全忘记了希腊和拉丁名词衰落的规则，并认为它是如何拼写的 我完全忘记了希腊和拉丁名词衰落的规则，并指出了一个非问题。 他们将Cerberus和Kerberos的拼写混为一谈，让Cerberos成为希腊和罗马血统的基础哨兵。

_{显然，Cerberus的头部数量是可变的。 也许这更好地表达为“头狗，其中大于或等于1”。}

Cerberus was the three headed dog¹ who guarded the gates of hell, keeping those trapped within from crossing back over the river Styx. Whomever wrote that section fancied Greek and/or Roman mythology and decided it would be an applicable name for a local variable sentry.

As to why it ends in os, one can imagine three scenarios:

They completely forgot the rules for Greek and Latin noun declinati and thought that was how it is spelled I completely forgot the rules for Greek and Latin noun declinati and am pointing out a non-issue. They conflated the spellings of Cerberus and Kerberos, giving birth to Cerberos the basic_stream sentry of Greek and Roman descent.

_{1. Apparently the number of heads on Cerberus is variable. Perhaps this is better expressed as the "-headed dog, where is greater than or equal to 1."}