Re: [boost] [gsoc16] Can I quickly check if the below really is the best approach?

Subject: Re: [boost] [gsoc16] Can I quickly check if the below really is the best approach?
From: Shangtong Zhang (zhangshangtong.cpp_at_[hidden])
Date: 2016-01-16 02:06:48

Hi,

> // At global scope, allocates no memory whatsoever
> static const constexpr static_map<int, const char *> map {
>  { 5, "apple" },
>  { 8, "pear" },
>  { 0, "banana" },
>  ...
> };
> // Works, constexpr "apple"
> constexpr const char *what_is_5 = map[5];
> // Works
> assert(map[5] && !strcmp(map[5], "apple");
> // Works
> map[5]="orange";
> assert(map[5] && !strcmp(map[5], "orange");
> // Throws exception as there is no key 6
> map[6];
> map.at <http://map.at/>(6);

I have difficulty understanding this, 
As variable map is const and constexpr, how can map[5]=“orange” work?
I don’t know how to implement this, where to store the “orange”.
Could anyone help me?

Thanks,

Shangtong Zhang,
Senior Student,
School of Computer Science,
Fudan University, PRC.