A C++ Kernel

Output and error streams

std::cout and std::cerr are correctly redirected



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#include <iostream>

std::cout << "some output" << std::endl;



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std::cerr << "some error" << std::endl;

Omitting the ; in the last statement of a cell gives an output



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int j = 5;



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j



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#include <map>



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std::map<std::string, int> map1;
map1["something"] = 69;
map1["anything"] = 199;
map1["that thing"] = 50;

map1



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#include <string>
#include <fstream>

#include "xtl/xbase64.hpp"
#include "xeus/xjson.hpp"

namespace im
{
    struct image
    {   
        inline image(const std::string& filename)
        {
            std::ifstream fin(filename, std::ios::binary);   
            m_buffer << fin.rdbuf();
        }
        
        std::stringstream m_buffer;
    };
    
    xeus::xjson mime_bundle_repr(const image& i)
    {
        auto bundle = xeus::xjson::object();
        bundle["image/png"] = xtl::base64encode(i.m_buffer.str());
        return bundle;
    }
}



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im::image marie("marie.png");
marie

Interpreting the C++ programming language

cling has a broad support of the features of C++. You can define functions, classes, templates, etc ...

Functions



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double sqr(double a)
{
    return a * a;
}



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double a = 2.5;
double asqr = sqr(a);
asqr

Classes



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class Foo
{
public:

    virtual ~Foo() {}
    
    virtual void print(double value) const
    {
        std::cout << "Foo value = " << value << std::endl;
    }
};



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Foo bar;
bar.print(1.2);

Polymorphism



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class Bar : public Foo
{
public:

    virtual ~Bar() {}
    
    virtual void print(double value) const
    {
        std::cout << "Bar value = " << 2 * value << std::endl;
    }
};



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Foo* bar2 = new Bar;
bar2->print(1.2);
delete bar2;

Templates



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#include <typeinfo>

template <class T>
class FooT
{
public:
    
    explicit FooT(const T& t) : m_t(t) {}
    
    void print() const
    {
        std::cout << typeid(T).name() << " m_t = " << m_t << std::endl;
    }
    
private:
    
    T m_t;
};

template <>
class FooT<int>
{
public:
    
    explicit FooT(const int& t) : m_t(t) {}
    
    void print() const
    {
        std::cout << "m_t = " << m_t << std::endl;
    }
    
private:
    
    int m_t;
};



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FooT<double> foot1(1.2);
foot1.print();



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FooT<int> foot2(4);
foot2.print();

C++11 / C++14 support



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class Foo11
{
public:
    
    Foo11() { std::cout << "Foo11 default constructor" << std::endl; }
    Foo11(const Foo11&) { std::cout << "Foo11 copy constructor" << std::endl; }
    Foo11(Foo11&&) { std::cout << "Foo11 move constructor" << std::endl; }
};



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Foo11 f1;
Foo11 f2(f1);
Foo11 f3(std::move(f1));



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#include <vector>

std::vector<int> v = { 1, 2, 3};
auto iter = ++v.begin();
v



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*iter

... and also lambda, universal references, decltype, etc ...

Documentation and completion



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?std::vector



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Foo