Re: What is the wrong with my C++ interfacing
On Monday, 16 March 2020 at 09:28:15 UTC, drug wrote: On 3/16/20 12:24 PM, Ferhat Kurtulmuş wrote: Ok, here is a solution. I opened my lib (yielded by my auxilary cpp) using 7zip. There are two files containing symbol names, 1.txt and 2.txt. I searched for names of member functions. They were not there because c++ compiler does not compile member functions of class templates because we don't actually use them. So, I simply include this line in my aux cpp file and recompiled it: template class cv::Size_; I reopened 1.txt and they are there now: ?area@?$Size_@H@cv@@QEBAHXZ ?aspectRatio@?$Size_@H@cv@@QEBANXZ now everything works :D Would be nice if you update wiki ;) It would be better for someone more experienced to do this ;)
Re: What is the wrong with my C++ interfacing
On 3/16/20 12:24 PM, Ferhat Kurtulmuş wrote: Ok, here is a solution. I opened my lib (yielded by my auxilary cpp) using 7zip. There are two files containing symbol names, 1.txt and 2.txt. I searched for names of member functions. They were not there because c++ compiler does not compile member functions of class templates because we don't actually use them. So, I simply include this line in my aux cpp file and recompiled it: template class cv::Size_; I reopened 1.txt and they are there now: ?area@?$Size_@H@cv@@QEBAHXZ ?aspectRatio@?$Size_@H@cv@@QEBANXZ now everything works :D Would be nice if you update wiki ;)
Re: What is the wrong with my C++ interfacing
On Monday, 16 March 2020 at 07:46:00 UTC, drug wrote:
On 3/16/20 10:11 AM, Ferhat Kurtulmuş wrote:
On Sunday, 15 March 2020 at 22:25:27 UTC, Arine wrote:
On Sunday, 15 March 2020 at 21:27:32 UTC, Ferhat Kurtulmuş
extern(C++, cv){
extern(C++, class) struct Size_(_Tp){
@disable this();
~this() { }
final _Tp area() const;
final double aspectRatio() const;
final bool empty() const;
_Tp width; //!< the width
_Tp height; //!< the height
}
}
extern(C++){
cv.Size_!int* createSizeIntWH(int w, int h);
}
void main()
{
Size_!int* sz = createSizeIntWH(200, 100);
writeln(sz.width);
}
This worked for me too. But member functions are still causing
linker error. It seems like docs
(https://dlang.org/spec/cpp_interface.html) do not cover those
situations. Is there any other sources to read for it. Maybe
you make a pull request to docs covering C++ interfacing tips
in detail.
Not tested:
extern(C++, class) struct Size_(_Tp){
@disable this();
~this() { }
extern(C++): // <- IIRC linkage should be set for members
separately from aggregate
final _Tp area() const;
final double aspectRatio() const;
final bool empty() const;
_Tp width; //!< the width
_Tp height; //!< the height
}
Ok, here is a solution. I opened my lib (yielded by my auxilary
cpp) using 7zip. There are two files containing symbol names,
1.txt and 2.txt. I searched for names of member functions. They
were not there because c++ compiler does not compile member
functions of class templates because we don't actually use them.
So, I simply include this line in my aux cpp file and recompiled
it:
template class cv::Size_;
I reopened 1.txt and they are there now:
?area@?$Size_@H@cv@@QEBAHXZ
?aspectRatio@?$Size_@H@cv@@QEBANXZ
now everything works :D
Re: What is the wrong with my C++ interfacing
On 3/16/20 10:11 AM, Ferhat Kurtulmuş wrote:
On Sunday, 15 March 2020 at 22:25:27 UTC, Arine wrote:
On Sunday, 15 March 2020 at 21:27:32 UTC, Ferhat Kurtulmuş
extern(C++, cv){
extern(C++, class) struct Size_(_Tp){
@disable this();
~this() { }
final _Tp area() const;
final double aspectRatio() const;
final bool empty() const;
_Tp width; //!< the width
_Tp height; //!< the height
}
}
extern(C++){
cv.Size_!int* createSizeIntWH(int w, int h);
}
void main()
{
Size_!int* sz = createSizeIntWH(200, 100);
writeln(sz.width);
}
This worked for me too. But member functions are still causing linker
error. It seems like docs (https://dlang.org/spec/cpp_interface.html) do
not cover those situations. Is there any other sources to read for it.
Maybe you make a pull request to docs covering C++ interfacing tips in
detail.
Not tested:
extern(C++, class) struct Size_(_Tp){
@disable this();
~this() { }
extern(C++): // <- IIRC linkage should be set for members separately
from aggregate
final _Tp area() const;
final double aspectRatio() const;
final bool empty() const;
_Tp width; //!< the width
_Tp height; //!< the height
}
Re: What is the wrong with my C++ interfacing
On Sunday, 15 March 2020 at 22:25:27 UTC, Arine wrote:
On Sunday, 15 March 2020 at 21:27:32 UTC, Ferhat Kurtulmuş
extern(C++, cv){
extern(C++, class) struct Size_(_Tp){
@disable this();
~this() { }
final _Tp area() const;
final double aspectRatio() const;
final bool empty() const;
_Tp width; //!< the width
_Tp height; //!< the height
}
}
extern(C++){
cv.Size_!int* createSizeIntWH(int w, int h);
}
void main()
{
Size_!int* sz = createSizeIntWH(200, 100);
writeln(sz.width);
}
This worked for me too. But member functions are still causing
linker error. It seems like docs
(https://dlang.org/spec/cpp_interface.html) do not cover those
situations. Is there any other sources to read for it. Maybe you
make a pull request to docs covering C++ interfacing tips in
detail.
Re: What is the wrong with my C++ interfacing
On Sunday, 15 March 2020 at 21:27:32 UTC, Ferhat Kurtulmuş wrote:
On Sunday, 15 March 2020 at 21:16:43 UTC, Arine wrote:
On Sunday, 15 March 2020 at 20:53:49 UTC, Ferhat Kurtulmuş
I wouldn't use a class on the D side, unless your C++ type
uses virtual functions. Classes in D are different from
structs, it is not the same as C++ where they are basically
the same thing.
I know their differences, classes are reference types and
structs are value types in D.
That's not the only difference. It's why your code doesn't work.
I actually don't need this code. I've already wrapped many c
code, but have no so much experience with interfacing C++ code.
I am trying to understand capabilities of D in interfacing with
C++ and its limits. I would like to know why I can interface a
template-free class, but not a class template.
You can, you just aren't representing the C++ code properly in D.
You don't want class, it means something different in D than in
C++.
This works for me, as it is using struct that corresponds to the
C++ type. You have to use extern(C++, class), as it is using
"class" on the C++ side, which produces a different mangling.
extern(C++, cv){
extern(C++, class) struct Size_(_Tp){
@disable this();
~this() { }
final _Tp area() const;
final double aspectRatio() const;
final bool empty() const;
_Tp width; //!< the width
_Tp height; //!< the height
}
}
extern(C++){
cv.Size_!int* createSizeIntWH(int w, int h);
}
void main()
{
Size_!int* sz = createSizeIntWH(200, 100);
writeln(sz.width);
}
Re: What is the wrong with my C++ interfacing
On Sunday, 15 March 2020 at 21:16:43 UTC, Arine wrote: On Sunday, 15 March 2020 at 20:53:49 UTC, Ferhat Kurtulmuş I wouldn't use a class on the D side, unless your C++ type uses virtual functions. Classes in D are different from structs, it is not the same as C++ where they are basically the same thing. I know their differences, classes are reference types and structs are value types in D. I actually don't need this code. I've already wrapped many c code, but have no so much experience with interfacing C++ code. I am trying to understand capabilities of D in interfacing with C++ and its limits. I would like to know why I can interface a template-free class, but not a class template.
Re: What is the wrong with my C++ interfacing
On Sunday, 15 March 2020 at 20:53:49 UTC, Ferhat Kurtulmuş wrote:
On Sunday, 15 March 2020 at 20:46:14 UTC, drug wrote:
15.03.2020 23:25, Ferhat Kurtulmuş пишет:
On Sunday, 15 March 2020 at 20:21:57 UTC, drug wrote:
15.03.2020 22:39, Ferhat Kurtulmuş пишет:
What is the D version of `createSizeIntWH`? In C++ it
returns a pointer but in D version it returns an instance.
extern(C++){
cv.Size_!int createSizeInt();
cv.Size_!int createSizeIntWH(int w, int h);
void deleteSizeInt(ref cv.Size_!int sz);
}
createSizeIntWH returns a pointer to instance, not an
instance. Try:
cv.Size_!int* createSizeIntWH(int w, int h);
I doubt it because in
https://dlang.org/spec/cpp_interface.html#using_cpp_classes_from_d
cpp code:
Derived *createInstance(int i)
d code:
extern (C++){
...
Derived createInstance(int i);
}
I wouldn't use a class on the D side, unless your C++ type uses
virtual functions. Classes in D are different from structs, it is
not the same as C++ where they are basically the same thing.
Re: What is the wrong with my C++ interfacing
15.03.2020 23:53, Ferhat Kurtulmuş пишет:
I doubt it because in
https://dlang.org/spec/cpp_interface.html#using_cpp_classes_from_d
cpp code:
Derived *createInstance(int i)
d code:
extern (C++){
...
Derived createInstance(int i);
}
Ah, really, you use classes on D side.
Re: What is the wrong with my C++ interfacing
On Sunday, 15 March 2020 at 20:46:14 UTC, drug wrote:
15.03.2020 23:25, Ferhat Kurtulmuş пишет:
On Sunday, 15 March 2020 at 20:21:57 UTC, drug wrote:
15.03.2020 22:39, Ferhat Kurtulmuş пишет:
What is the D version of `createSizeIntWH`? In C++ it returns
a pointer but in D version it returns an instance.
extern(C++){
cv.Size_!int createSizeInt();
cv.Size_!int createSizeIntWH(int w, int h);
void deleteSizeInt(ref cv.Size_!int sz);
}
createSizeIntWH returns a pointer to instance, not an instance.
Try:
cv.Size_!int* createSizeIntWH(int w, int h);
I doubt it because in
https://dlang.org/spec/cpp_interface.html#using_cpp_classes_from_d
cpp code:
Derived *createInstance(int i)
d code:
extern (C++){
...
Derived createInstance(int i);
}
Re: What is the wrong with my C++ interfacing
15.03.2020 23:25, Ferhat Kurtulmuş пишет:
On Sunday, 15 March 2020 at 20:21:57 UTC, drug wrote:
15.03.2020 22:39, Ferhat Kurtulmuş пишет:
What is the D version of `createSizeIntWH`? In C++ it returns a
pointer but in D version it returns an instance.
extern(C++){
cv.Size_!int createSizeInt();
cv.Size_!int createSizeIntWH(int w, int h);
void deleteSizeInt(ref cv.Size_!int sz);
}
createSizeIntWH returns a pointer to instance, not an instance. Try:
cv.Size_!int* createSizeIntWH(int w, int h);
Re: What is the wrong with my C++ interfacing
On Sunday, 15 March 2020 at 20:21:57 UTC, drug wrote:
15.03.2020 22:39, Ferhat Kurtulmuş пишет:
What is the D version of `createSizeIntWH`? In C++ it returns a
pointer but in D version it returns an instance.
extern(C++){
cv.Size_!int createSizeInt();
cv.Size_!int createSizeIntWH(int w, int h);
void deleteSizeInt(ref cv.Size_!int sz);
}
Re: What is the wrong with my C++ interfacing
15.03.2020 22:39, Ferhat Kurtulmuş пишет:
The original C++ class
https://github.com/opencv/opencv/blob/master/modules/core/include/opencv2/core/types.hpp#L315:
template class Size_
{
public:
typedef _Tp value_type;
//! default constructor
Size_();
Size_(_Tp _width, _Tp _height);
Size_(const Size_& sz);
Size_(Size_&& sz) CV_NOEXCEPT;
Size_(const Point_<_Tp>& pt);
Size_& operator = (const Size_& sz);
Size_& operator = (Size_&& sz) CV_NOEXCEPT;
//! the area (width*height)
_Tp area() const;
//! aspect ratio (width/height)
double aspectRatio() const;
//! true if empty
bool empty() const;
//! conversion of another data type.
template operator Size_<_Tp2>() const;
_Tp width; //!< the width
_Tp height; //!< the height
};
// my auxiliary cpp code:
cv::Size_* createSizeIntWH(int _width, int _height){
return new cv::Size_(_width, _height);
}
void deleteSizeInt(cv::Size_ *&sz){
delete sz;
}
// d code:
extern(C++, cv){
class Size_(_Tp){
@disable this();
final _Tp area() const;
final double aspectRatio() const;
final bool empty() const;
_Tp width; //!< the width
_Tp height; //!< the height
}
}
// my test code that fails:
Size_!int sz = createSizeIntWH(200, 100);
writeln(sz.width);
What is the D version of `createSizeIntWH`? In C++ it returns a pointer
but in D version it returns an instance.
One of the problems is that sz.width is not printed as 200, but a random
int.
Other problem is that if I try to call one of area, aspectRatio, and
empty, it does not compile yielding a linker error:
error LNK2019: unresolved external symbol "public: int __cdecl
cv::Size_::area(void)const " (?area@?$Size_@H@cv@@QEBAHXZ)
referenced in function _Dmain
Somehow linker cannot locate that symbol. Is this a name mangling issue?
In the same library I could successfully interface cv::Mat which is a
template-free definition. I suspect if D allows interfacing C++ class
templates since docs do not cover this, but only struct templates?
What is the wrong with my C++ interfacing
The original C++ class
https://github.com/opencv/opencv/blob/master/modules/core/include/opencv2/core/types.hpp#L315:
template class Size_
{
public:
typedef _Tp value_type;
//! default constructor
Size_();
Size_(_Tp _width, _Tp _height);
Size_(const Size_& sz);
Size_(Size_&& sz) CV_NOEXCEPT;
Size_(const Point_<_Tp>& pt);
Size_& operator = (const Size_& sz);
Size_& operator = (Size_&& sz) CV_NOEXCEPT;
//! the area (width*height)
_Tp area() const;
//! aspect ratio (width/height)
double aspectRatio() const;
//! true if empty
bool empty() const;
//! conversion of another data type.
template operator Size_<_Tp2>() const;
_Tp width; //!< the width
_Tp height; //!< the height
};
// my auxiliary cpp code:
cv::Size_* createSizeIntWH(int _width, int _height){
return new cv::Size_(_width, _height);
}
void deleteSizeInt(cv::Size_ *&sz){
delete sz;
}
// d code:
extern(C++, cv){
class Size_(_Tp){
@disable this();
final _Tp area() const;
final double aspectRatio() const;
final bool empty() const;
_Tp width; //!< the width
_Tp height; //!< the height
}
}
// my test code that fails:
Size_!int sz = createSizeIntWH(200, 100);
writeln(sz.width);
One of the problems is that sz.width is not printed as 200, but a
random int.
Other problem is that if I try to call one of area, aspectRatio,
and empty, it does not compile yielding a linker error:
error LNK2019: unresolved external symbol "public: int __cdecl
cv::Size_::area(void)const " (?area@?$Size_@H@cv@@QEBAHXZ)
referenced in function _Dmain
Somehow linker cannot locate that symbol. Is this a name mangling
issue?
In the same library I could successfully interface cv::Mat which
is a template-free definition. I suspect if D allows interfacing
C++ class templates since docs do not cover this, but only struct
templates?
