C ++方法需要参考，无法让Cython提供一个

Question

我通过Cython将Python连接到名为Bullet Physics的C ++库。我有很多工作，但是一个问题困扰着我。这是在多种情况下发生的问题的示例。

Bullet Physics .h文件声明了一个方法，我将其复制并合并到我的cdef中，如下所示：

cdef cppclass btSliderConstraint:
    btSliderConstraint *btSliderConstraint(btRigidBody& rbA, btRigidBody& rbB, const btTransform& frameInA, const btTransform& frameInB, bool useLinearReferenceFrameA)

问题是如何在对该方法的Cython调用中指定rbA和rbB 引用（＆rbA和＆rbB）。我有很多指向btRigidBody对象的指针，但是此方法的声明要求参数是引用（除非我弄错了）。

如果我仅尝试为rbA和rbB提供指向btRigidBody对象的指针，则cython编译器会抱怨：

Error compiling Cython file:
------------------------------------------------------------
    cdef btRigidBody *b1
    cdef btRigidBody *b2
    # bs.bodies is an array of pointers to btRigidBody objects, nbi and ji1 are integer indices
    b1 = bs.bodies[nbi]
    b2 = bs.bodies[ji1]
    motor = new btSliderConstraint(b1, b2, tra, trb, 1);
                                        ^
------------------------------------------------------------

fun4.pyx:922:41: Cannot assign type 'btRigidBody *' to 'btRigidBody'

我的强制转换或取消引用等尝试均未完成这项工作。在纯C ++中，这似乎很容易做到，但是在Cython中，我尝试过的所有方法似乎都没有效果。

如果我能够简单地声明btRigidBody类型的变量，如下所示：

cdef btRigidBody rbA

那么我相信我可以将其作为参数传递，并且编译器不会抱怨。我在其他情况下也可以这样做。但是，我不想在这里这样做，因为我已经有一个指向要作为参数传递的对象的指针，而且，以这种方式进行操作将要求btRigidBody对象和库没有提供不带任何参数的构造函数，并且出于可维护性的原因，我不想对库进行修改。

因此，如何在Cython中将指针转换为我拥有的btRigidBody对象以及所需的btRigidBody引用？

编辑：

*取消对指针的引用的明显用法在Cython中不起作用（尽管我认为它将在C ++中起作用）。在Cython中，它给出了许多令人困惑的错误：

Error compiling Cython file:
------------------------------------------------------------
...
    cdef btRigidBody *b1
    cdef btRigidBody *b2
    # bs.bodies is an array of pointers to btRigidBody objects, nbi and ji1 are integer indices
    b1 = bs.bodies[nbi]
    b2 = bs.bodies[ji1]
    motor = new btSliderConstraint(*b1, *b2, tra, trb, 1);
                                 ^
------------------------------------------------------------

fun4.pyx:922:34: Non-trivial keyword arguments and starred arguments not allowed in cdef functions.

Error compiling Cython file:
------------------------------------------------------------
...
    cdef btRigidBody *b1
    cdef btRigidBody *b2
    # bs.bodies is an array of pointers to btRigidBody objects, nbi and ji1 are integer indices
    b1 = bs.bodies[nbi]
    b2 = bs.bodies[ji1]
    motor = new btSliderConstraint(*b1, *b2, tra, trb, 1);
                                     ^
------------------------------------------------------------

fun4.pyx:922:38: Cannot convert 'btRigidBody *' to Python object

Error compiling Cython file:
------------------------------------------------------------
...
    cdef btRigidBody *b1
    cdef btRigidBody *b2
    # bs.bodies is an array of pointers to btRigidBody objects, nbi and ji1 are integer indices
    b1 = bs.bodies[nbi]
    b2 = bs.bodies[ji1]
    motor = new btSliderConstraint(*b1, *b2, tra, trb, 1);
                                          ^
------------------------------------------------------------

fun4.pyx:922:43: Cannot convert 'btRigidBody *' to Python object

Error compiling Cython file:
------------------------------------------------------------
...
    cdef btRigidBody *b1
    cdef btRigidBody *b2
    # bs.bodies is an array of pointers to btRigidBody objects, nbi and ji1 are integer indices
    b1 = bs.bodies[nbi]
    b2 = bs.bodies[ji1]
    motor = new btSliderConstraint(*b1, *b2, tra, trb, 1);
                                               ^
------------------------------------------------------------

fun4.pyx:922:48: Cannot convert 'btTransform' to Python object

Error compiling Cython file:
------------------------------------------------------------
...
    cdef btRigidBody *b1
    cdef btRigidBody *b2
    # bs.bodies is an array of pointers to btRigidBody objects, nbi and ji1 are integer indices
    b1 = bs.bodies[nbi]
    b2 = bs.bodies[ji1]
    motor = new btSliderConstraint(*b1, *b2, tra, trb, 1);
                                                    ^
------------------------------------------------------------

fun4.pyx:922:53: Cannot convert 'btTransform' to Python object

Error compiling Cython file:
------------------------------------------------------------
...
    cdef btRigidBody *b1
    cdef btRigidBody *b2
    # bs.bodies is an array of pointers to btRigidBody objects, nbi and ji1 are integer indices
    b1 = bs.bodies[nbi]
    b2 = bs.bodies[ji1]
    motor = new btSliderConstraint(*b1, *b2, tra, trb, 1);
                                 ^
------------------------------------------------------------

fun4.pyx:922:34: Cannot convert Python object to 'btSliderConstraint *'

Error compiling Cython file:
------------------------------------------------------------
...
    cdef btRigidBody *b1
    cdef btRigidBody *b2
    # bs.bodies is an array of pointers to btRigidBody objects, nbi and ji1 are integer indices
    b1 = bs.bodies[nbi]
    b2 = bs.bodies[ji1]
    motor = new btSliderConstraint(*b1, *b2, tra, trb, 1);
                                 ^
------------------------------------------------------------

fun4.pyx:922:34: Storing unsafe C derivative of temporary Python reference

Answer 1

由于Cython的目标是保留Python语法，因此无法使用*进行指针取消引用。而是使用[]。以下是所需的操作：

motor = new btSliderConstraint（bs.bodies [nbi] [0]，bs.bodies [ji1] [0]，tra，trb，1）;