Trace for VisualStudio

trace

#include <sstream>
#include <thread>
#include <cstdio>
#include <cstdarg>
#include <cwchar>
#include <cstdlib>
#include <windows.h>

struct DebugOutImpl {
	DebugOutImpl(const char* location, int line, bool enabled_ = true)
	:enabled(enabled_)
	{
		ss << location << line << "): " << std::this_thread::get_id() << " - ";
	}
	~DebugOutImpl()  { ss << '\n'; OutputDebugStringA(ss.str().c_str()); }
	void operator()(const char* msg) { if (enabled) ss << msg; }
	void operator()(const wchar_t* msg) { if (enabled) ss << wtoa(msg); }
	std::ostringstream& operator()() { return ss; }
	template<class char_type>
	void operator()(const char_type* format, ...) {
		if (enabled) {
			char_type buf[4096];
			va_list ap;
			va_start(ap, format);
			vsnprintf_s(buf, 4096, format, ap);
			va_end(ap);
			operator()(buf);
		}
	}
private:
	static std::string wtoa(const wchar_t* ptr, size_t len = -1){
		if (len == -1) len = wcslen(ptr);
		std::string r(WideCharToMultiByte(CP_THREAD_ACP, 0, ptr, len, nullptr, 0, 0, 0), '\0');
		if (r.size() == 0) throw std::system_error(GetLastError(), std::system_category());
		if (0 == WideCharToMultiByte(CP_THREAD_ACP, 0, ptr, len, &r[0], r.size(), 0, 0))
			throw std::system_error(GetLastError(), std::system_category(), "error converting wide string to narrow");
		return r;
	}
	static inline std::string wtoa(const std::wstring& wstr) { return wtoa(&wstr[0], wstr.size()); }
	static int vsnprintf_s(char* buffer, int bufsize, const char* format, va_list ap) { return ::vsnprintf_s(buffer, bufsize, _TRUNCATE, format, ap); }
	static int vsnprintf_s(wchar_t* buffer, int bufsize, const wchar_t* format, va_list ap) { return ::vswprintf_s(buffer, bufsize, format, ap); }

	std::ostringstream ss;
	bool enabled;
};
#define DebugOut DebugOutImpl(__FILE__ "(", __LINE__)


int main() {
	std::string name = "bob";
	int age = 25;

	DebugOut("HI");
	DebugOut("my name is %s", name.c_str());
	DebugOut() << name << " is age " << age;
	return 0;
}