Support for T&& function parameters and the special move constructor case #24
Comments
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I don't remember where the issue comes from. The easiest way to start with to address it, is to comment this part of code and run wrapit on a function that takes a pass-by-r-value argument. |
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Thanks, well the generated code errors in circle.hh #include <iostream>
#include <utility>
using namespace std;
class Circle {
public:
Circle(int r)
{
_radius = r;
cout << "Standard constructor. Radius: " << _radius << endl;
}
Circle(const Circle& c)
{
_radius = c.radius();
cout << "Copy constructor with lvalue reference. Radius: " << _radius << endl;
}
Circle(Circle&& c)
{
_radius = c.radius();
cout << "Move constructor with rvalue reference. Radius: " << _radius << endl;
}
int radius() const {
return _radius;
}
private:
int _radius;
};
void test()
{
cout << "== from c++ ==" << endl;
Circle c1(2);
Circle c2(c1);
Circle c3(std::move(c2));
}conf.toml module_name = "Circ"
input = ["circle.hh"]
#include <type_traits>
#include "jlcxx/jlcxx.hpp"
#include "jlcxx/functions.hpp"
#include "jlcxx/stl.hpp"
#include "jlCirc.h"
#ifdef VERBOSE_IMPORT
# define DEBUG_MSG(a) std::cerr << a << "\n"
#else
# define DEBUG_MSG(a)
#endif
#define __HERE__ __FILE__ ":" QUOTE2(__LINE__)
#define QUOTE(arg) #arg
#define QUOTE2(arg) QUOTE(arg)
namespace jlcxx {
template<> struct IsMirroredType<Circle> : std::false_type { };
template<> struct DefaultConstructible<Circle> : std::false_type { };
}
JLCXX_MODULE define_julia_module(jlcxx::Module& types){
DEBUG_MSG("Adding wrapper for type Circle (" __HERE__ ")");
// defined in ./circle.hh:6:7
auto t0 = types.add_type<Circle>("Circle");
/**********************************************************************/
/* Wrappers for the methods of class Circle
*/
DEBUG_MSG("Adding wrapper for void Circle::Circle(int) (" __HERE__ ")");
// defined in ./circle.hh:8:5
t0.constructor<int>(/*finalize=*/true);
DEBUG_MSG("Adding wrapper for void Circle::Circle(const Circle &) (" __HERE__ ")");
// defined in ./circle.hh:14:5
t0.constructor<const Circle &>(/*finalize=*/true);
DEBUG_MSG("Adding wrapper for void Circle::Circle(Circle &&) (" __HERE__ ")");
// defined in ./circle.hh:20:5
t0.constructor<Circle &&>(/*finalize=*/true);
DEBUG_MSG("Adding wrapper for int Circle::radius() (" __HERE__ ")");
// signature to use in the veto list: int Circle::radius()
// defined in ./circle.hh:26:9
t0.method("radius", static_cast<int (Circle::*)() const>(&Circle::radius));
/* End of Circle class method wrappers
**********************************************************************/
/**********************************************************************
* Wrappers for global functions and variables including
* class static members
*/
DEBUG_MSG("Adding wrapper for void test() (" __HERE__ ")");
// signature to use in the veto list: void test()
// defined in ./circle.hh:34:6
types.method("test", static_cast<void (*)() >(&test));
/* End of global function wrappers
**********************************************************************/
DEBUG_MSG("End of wrapper definitions");
}error log |
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It's a CxxWrap limitation. When do you want the move constructor to be called? It is not clear to me how you'd like to map the copy and move constructors to Julia. |
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Yes, it's unclear to me conceptually too how a move constructor would be called from the julia side, so it might be a dead end. However, I'm wrapping a library that I'm in no position of modifying its sources. |
grasph
changed the title
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I see. I'm adding @barche to get its opinion. It's not clear to me know the move-only class should be handled, and more general pass-by-rvalue function parameters. The std::uniq_ptr is one notorious example of move-only class. As @t-bltg highlighted, Wrapit currently skip move-constructor and any function with a T&& parameter. @t-bltg, if you give more insights on the class you want to wrap, this might help to understand use cases and how mapping to Julia should be done. Philippe. |
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Thanks Philippe, I cannot disclose the sources, but here is a reduced example of what is intended to be wrapped (you were dead-on right about #include <memory>
struct Options;
enum class State
{
IDLE = 0,
RUNNING = 1,
};
class CurrentState
{
public:
explicit CurrentState(std::unique_ptr<Options> && Options);
~CurrentState();
CurrentState(CurrentState const &) = delete;
CurrentState(CurrentState &&) = delete;
CurrentState & operator=(CurrentState const &) = delete;
CurrentState & operator=(CurrentState &&) = delete;
State getState() const
{ return m_state; }
private:
State m_state;
std::unique_ptr<Options> m_Options;
}; |
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Let's wait from @barche's inputs to see how to handle this case. If you need an immediate solution, here is a workaround, you can use in the meantime. Define a function in a header file you add to the WrapIt CurrentState createCurrentState(const Option& o){
return CurrentState(std::make_unique<Option>(o));
}Then, either require calling this function instead of the usual constructor or, for a more transparent use, define a constructor inside the julia module: CurrentState(o::Option) = createCurrentState(o)To customize the julia module, you can use the pattern of ex002-ROOT: export list is generated in a separate file and the generated master file (limited to few lines) is discarded and replaced by a custom file. This will also allow you customizing the shared library path and solve at the same time the Issue #18. Philippe. |
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That's a nice workaround ! Regarding #18, I ended up writing my own module, however from a user point of view (a beginner using |
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I think @grasph 's workaround is the only way for now. There is currently no way to directly wrap the move constructor, but it seems like it would be a nice feature to have. I think it should be possible to also provide a |
In
wrapit/src/FunctionWrapper.cpp
Lines 570 to 579 in 3cb7ace
The generated code does not compile, right, but where should this be fixed ?
Is it a limitation in
wrapit,CxxWraporlibcxxwrap-julia?I'd like to try to fix this, but I will need some pointers to start, so any comment would be very helpful.
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