random-code/factory.cpp at master · KillzoneKid/random-code · GitHub

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/*
A factory pattern design using map, lambdas and polymorphism
https://ideone.com/Bj51fT
*/

#include<map>
#include<functional>
#include<iostream>
#include<string>

classBase
{
public:
virtual~Base() = default;
virtual std::string whatBaseAmI() = 0;
virtualunsignedlongtoDec() = 0;
};

classHex : publicBase
{
	std::string _number;
public:
Hex(std::string number) : _number(number) {}
unsignedlongtoDec() override { returnstd::strtoul(_number.c_str(), NULL, 16); }
	std::string whatBaseAmI() override { return"Hex"; }
};

classBinary : publicBase
{
	std::string _number;
public:
Binary(std::string number) : _number(number) {}
unsignedlongtoDec() override { returnstd::strtoul(_number.c_str(), NULL, 2); }
	std::string whatBaseAmI() override { return"Binary"; }
};

intmain()
{
	std::map<std::string, std::function<Base *(std::string const &)>> factory =
	{
 { "Binary", [](std::string const &number) { returnnewBinary(number); } },
 { "Hex", [](std::string const &number) { returnnewHex(number); } }
	};

	Base *b = factory["Binary"]("1001001001001");

if (b)
	{
 std::cout << "Base: " << b->whatBaseAmI() << std::endl;
 std::cout << "Decimal Value: " << b->toDec() << std::endl;
	}

return0;
}