First implementation

It seems to work but I think the ticker value returned
by the remote call is wrong. Maybe I'm calling the wrong
endpoint ¯\_(ツ)_/¯ I don't know trying to work it out

src/main.cpp

@@ -0,0 +1,135 @@
+/* Copyright 2022, Michele Santullo
+ * This file is part of duckticker.
+ *
+ * Wrenpp is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Wrenpp is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with duckticker.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "nap/quick_rest.hpp"
+#include <simdjson.h>
+#include <wrenpp/vm_fun.hpp>
+#include <wrenpp/def_configuration.hpp>
+#include <utility>
+
+namespace {
+constexpr char g_script[] =
+R"script(
+foreign class TickerPrice {
+	construct new() { }
+
+	foreign price
+	foreign currency
+}
+
+class Bitcoinity {
+	foreign static ticker(currency)
+}
+
+class App {
+	construct new(currency) {
+		_currency = currency
+	}
+
+	start() {
+		var price = Bitcoinity.ticker(_currency)
+		System.print("Ticker: %(price.price) %(price.currency)")
+	}
+}
+
+var the_app = App.new("USD")
+)script";
+
+class TickerPrice {
+public:
+	TickerPrice() = default;
+	TickerPrice (double price, std::string&& currency) :
+		m_price(price),
+		m_currency(std::move(currency))
+	{}
+
+	void set_price (double price) { m_price = price; }
+	void set_currency (std::string&& currency) { m_currency = std::move(currency); }
+	double price() const noexcept { return m_price; }
+	const char* currency() const noexcept { return m_currency.c_str(); }
+
+private:
+	double m_price{};
+	std::string m_currency;
+};
+
+TickerPrice ticker_price (std::string_view currency) {
+	nap::QuickRest qrest{simdjson::SIMDJSON_PADDING};
+	qrest.set_user_agent("duckticker");
+	qrest.add_post("currency", currency);
+
+	auto response = qrest.fetch("https://bitcoinity.org/simple_switch_currency");
+	//std::cout << response.body << '\n';
+
+	simdjson::ondemand::parser parser;
+	simdjson::padded_string_view body{response.body, response.body.size() + simdjson::SIMDJSON_PADDING};
+	simdjson::ondemand::document doc = parser.iterate(body);
+	const double price_out = doc["price"];
+	const std::string_view currency_out = doc["currency"];
+	return {price_out, std::string{currency_out}};
+}
+
+void ticker_price_wren (wren::VM& vm) {
+	TickerPrice* const tp = wren::make_foreign_object<TickerPrice>(vm, "main");
+	*tp = ticker_price(wren::get<const char*>(vm, 1));
+}
+
+class MyWrenConfiguration : public wren::DefConfiguration {
+public:
+	wren::foreign_method_t foreign_method_fn(
+		wren::VM* vm,
+		std::string_view module,
+		std::string_view class_name,
+		bool is_static,
+		std::string_view signature
+	) {
+		if ("main" == module) {
+			if (is_static and "Bitcoinity" == class_name and "ticker(_)" == signature) {
+				return &ticker_price_wren;
+			}
+			else if ("TickerPrice" == class_name) {
+				if (not is_static and "price" == signature)
+					return wren::make_method_bindable<&TickerPrice::price>();
+				else if (not is_static and "currency" == signature)
+					return wren::make_method_bindable<&TickerPrice::currency>();
+			}
+		}
+		return nullptr;
+	}
+
+	wren::foreign_class_t foreign_class_fn(
+		wren::VM* vm,
+		std::string_view module,
+		std::string_view class_name
+	) {
+		if (module == "main" and class_name == "TickerPrice")
+			return wren::make_foreign_class<TickerPrice>();
+		else
+			return {nullptr, nullptr};
+	}
+};
+} //unnamed namespace
+
+int main() {
+	MyWrenConfiguration config;
+	wren::VM vm(&config, nullptr);
+	vm.interpret("main", g_script);
+
+	wren::call<void>(vm, {"main", "the_app"}, "start");
+
+	return 0;
+}