Adding struct containing not copyable/moveable object to std::map

Question

I have this MCVE:

#include <atomic>
#include <map>
#include <string>

struct foo
{
    int intValue;
    std::atomic_bool bar;

    foo( int intValue ) : intValue( intValue ) {};
};

std::map<std::string, foo> myMap;

int main()
{
    myMap.emplace( "0",  1234 );
}

It does not compile because std::atomic is neither copyable nor movable.

My question:

How can I add a class containing a not copyable/moveable object to a std::map container?

You really should not use `const char*` as a key to a mapping. That's because it will be the *pointer* that is the key, not what it points to. — Some programmer dude, Sep 04 '16 at 00:44
@JoachimPileborg: This is an `MCVE`. In my real project it is `std::string` and `foo` is much more complicated. I wanted to make it really very small. Thx — Peter VARGA, Sep 04 '16 at 00:45
For future reference, when creating a MCVE, please don't add possible other sources of errors, as that will only confuse us. Actually *create* an MCVE, as close to your actual program as possible. — Some programmer dude, Sep 04 '16 at 00:48

score 3 · Accepted Answer · answered Sep 04 '16 at 00:38

3

What about

myMap.emplace(std::piecewise_construct,
              std::forward_as_tuple("0"),
              std::forward_as_tuple(1234));

?

answered Sep 04 '16 at 00:38

max66

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1

@AlBundy You'd have heard about it if you'd _read_ and _studied_ the documentation for `std::map` as part of planning for this task... – Lightness Races in Orbit Sep 04 '16 at 01:08
@LightnessRacesinOrbit [http://en.cppreference.com/w/cpp/container/map/emplace](http://en.cppreference.com/w/cpp/container/map/emplace) has the example but - this I checked first due to Google sort order - [http://www.cplusplus.com/reference/map/map/emplace/](http://www.cplusplus.com/reference/map/map/emplace/) does **not**. – Peter VARGA Sep 04 '16 at 01:44
4

@LightnessRacesinOrbit no need for such comments imho – M.M Sep 04 '16 at 07:50
@M.M: Teach a man to fish, mate. It's the single most helpful thing you'll do all day. Thanks for your constructive contribution to this thread, though (can't believe you came here _just_ to say that - no need for such comments imho) – Lightness Races in Orbit Sep 04 '16 at 13:35

Adding struct containing not copyable/moveable object to std::map

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