google / cpp-from-the-sky-down

C++ From The Sky Down - Libraries and Examples

This repository will hold explanations, documentations,examples and libraries developed for C++ From The Sky Down.

C++ From the Sky Down is a series designed to present C++ as a high-level language and to show techniques and libraries (including some developed during this course) to use C++ as a high level language while hiding the low-level stuff.

This will use C++17 and C++20 (as they become available) features.

More explanations/documentations/examples/libraries will be added as the series progresses.

g/cpp-from-the-sky-down

This is not an officially supported Google product.

cpp-from-the-sky-down's Issues

Read me file

Lack of descriptiveness in the README.md file. The project idea is not that clear as it should be.

Anyway to make polymorphy for self-deriving methods?

struct A {
    int id{0};
    A derive() {
        A ret{*this};
        ret.id += 1;
        return ret;
    }
};

struct interface_derive: polymorphic::ref<interface_derive(tag_derive)> {};
using implement_derive = polymorphic::object<interface_derive(tag_derive)>;

compiles error:
no known conversion from 'A' to 'interface_derive &&' for 1st argument

How to run the example code in the cpp20_sql?

Hi, thanks for the hard work. I installed sqlite and g++10, and I compiled the example file with g++-10 -o example example.cpp -I ./sqlite -std=c++2a but I got the error message of no matching function to call with fixed_string(auto)... Not sure at what step things went wrong...

Compiler error with const

Hello there,

After watching the excellent CppCon talk by John Bandela (https://youtu.be/PSxo85L2lC0) I've been experimenting with the polymorphic library but have run into a strange compile error I've been struggling to work out. Here's the snippet I have...

#include "polymorphic.hpp"

#include <iostream>
#include <string>
#include <vector>
#include <memory>

struct Box {
    void draw() const {
        std::cout << "box" << "\n";
    }
};

struct Circle {
    void draw() const {
        std::cout << "circle" << "\n";
    }
};

struct Triangle {
    void draw() const {
        std::cout << "triangle" << "\n";
    }
};

struct draw {};
using draw_signature = void(draw) const;

void drawing(polymorphic::ref<draw_signature> drawable) {
    drawable.call<draw>();
}

template<typename T>
void poly_extend(draw, const T& t) {
    t.draw();
}

using shape = polymorphic::object<draw_signature>;

int main(int argc, char** argv) {
    Circle c;
    Box b;
    Triangle t;

    drawing(b);
    drawing(c);
    drawing(t);

    shape s1 {c};
    drawing(s1); // does not compile

    return 0;
}

If you do a find-replace and remove all the consts it totally compiles and runs fine - if someone could tell me what I'm doing wrong I'd be very grateful!

Thanks!

Tom

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