blocks|key|488006|text|对于每个cdef类，创建一个充当构造函数的全局cdef函数，CefResponse是一个C%2B%2B对象，PyResponse是c%2B%2B对象的python等效项：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|488007|cdef+object+CreatePyResponse(CefRefPtr[CefResponse]+cefResponse):

++++pyResponse+=+PyResponse()
++++pyResponse.cefResponse+=+cefResponse
++++return+pyResponse

cdef+class+PyResponse:

++++cdef+CefRefPtr[CefResponse]+cefResponse

++++def+GetStatus(self):

++++++++return+(<CefResponse*>(self.cefResponse.get())).GetStatus()|code-block|syntax|javascript|488008|所以调用resp+=+CreatePyResponse(cppObject)而不是resp+=+PyResponse(cppObject)。|offset|length|style|CODE|488009|取自CEF+Python的示例：https://code.google.com/p/cefpython/source/browse/cefpython/response.pyx?r=0250b65e046a|488010|entityMap|0|LINK|mutability|MUTABLE|url|https://code.google.com/p/cefpython/source/browse/cefpython/response.pyx?r=0250b65e046a^0|0|0|4|Y|15|S|0|G|2F|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@$I|Z|J|10|K|L]|$I|11|J|12|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|13|8|@]|9|@$I|14|J|15|1|16]]|A|$]]|$1|O|3|-4|5|6|7|17|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

For each cdef class create a global cdef function that acts as a constructor, CefResponse is a C++ object, PyResponse a python equivalent of a c++ object:

<pre><code>cdef object CreatePyResponse(CefRefPtr[CefResponse] cefResponse):

 pyResponse = PyResponse()
 pyResponse.cefResponse = cefResponse
 return pyResponse

cdef class PyResponse:

 cdef CefRefPtr[CefResponse] cefResponse

 def GetStatus(self):

 return (&lt;CefResponse*&gt;(self.cefResponse.get())).GetStatus()
</code></pre>

So instead of <code>resp = PyResponse(cppObject)</code> call <code>resp = CreatePyResponse(cppObject)</code>.

Example taken from CEF Python:
<a href="https://code.google.com/p/cefpython/source/browse/cefpython/response.pyx?r=0250b65e046a" rel="nofollow">https://code.google.com/p/cefpython/source/browse/cefpython/response.pyx?r=0250b65e046a</a>

blocks|key|270953|text|Python类接受Python参数。要传递C%2B%2B参数，需要对其进行包装：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|270954|#+distutils:+language+=+c%2B%2B

cdef+extern+from+"Foo.h"+namespace+"baz":
++++cdef+cppclass+Bar:
+++++++++Bar(double+d)
+++++++++double+get()

cdef+class+PyBar:+#+wrap+Bar+class
++++cdef+Bar+*thisptr
++++def+__cinit__(self,+double+d):
++++++++self.thisptr+=+new+Bar(d)
++++def+__dealloc__(self):
++++++++del+self.thisptr
++++property+d:
++++++++def+__get__(self):
++++++++++++return+self.thisptr.get()|code-block|syntax|javascript|270955|PyBar实例可以用作来自Cython和纯Python的任何其他Python对象：|offset|length|style|CODE|270956|class+PyClass:
++++def+__init__(self,+PyBar+bar):
++++++++self.bar+=+bar

print(PyClass(PyBar(1)).bar.d)|270957|entityMap^0|0|0|0|5|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Python class accepts Python arguments. To pass a C++ argument you need to wrap it:

<pre><code># distutils: language = c++

cdef extern from "Foo.h" namespace "baz":
 cdef cppclass Bar:
 Bar(double d)
 double get()

cdef class PyBar: # wrap Bar class
 cdef Bar *thisptr
 def __cinit__(self, double d):
 self.thisptr = new Bar(d)
 def __dealloc__(self):
 del self.thisptr
 property d:
 def __get__(self):
 return self.thisptr.get()
</code></pre>

<code>PyBar</code> instances can be used as any other Python objects both from Cython and pure Python:

<pre><code>class PyClass:
 def __init__(self, PyBar bar):
 self.bar = bar

print(PyClass(PyBar(1)).bar.d)
</code></pre>

blocks|key|271007|text|我在尝试用结构将C代码包装为python类时遇到了这个问题。问题似乎是，包括__init__和__cinit__在内的“特殊”函数必须声明为def而不是cdef。这意味着它们可以从普通的python中调用，所以类型参数实际上被忽略了，所有的东西都被当作对象来处理。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|271008|在J.F.Sebastian的回答中，修复方法不是包装-+double是一种基本的数字类型，因此在C/C%2B%2B类型和Python对象之间存在默认转换。Czarek的答案基本上是正确的--你需要使用一个假的构造函数，使用一个全局函数。不能使用@staticmethod修饰器，因为它们不能应用于cdef函数。在提供的原始示例中，答案看起来更简单。|271009|cdef+extern+from+"Foo.h":
++++cdef+cppclass+Bar:
++++++++pass

cdef+class+PyClass:
++++cdef+Bar+*bar

cdef+PyClass_Init(Bar+*b):
++++result+=+PyClass()
++++result.bar+=+b
++++return+result|code-block|syntax|javascript|271010|entityMap^0|12|8|1B|9|1Y|3|24|4|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|Y|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|N|$]]

I came across this problem trying to wrap C code with structs as python classes. The issue seems to be that "special" function including <code>__init__</code> and <code>__cinit__</code> must be declared as <code>def</code> rather than <code>cdef</code>. This means that they can be called from normal python, so the type parameters are effectively ignored and everything is treated as object.

In J.F. Sebastian's answer the fix is not the wrapping - a double is a basic numeric type and so there is a default conversion between the C/C++ type and the Python object. Czarek's answer is basically correct - you need to use a fake constructor idiom, using a global function. It is not possible to use a @staticmethod decorator as they cannot be applied to cdef functions. The answer looks simpler on the original example provided.

<pre><code>cdef extern from "Foo.h":
 cdef cppclass Bar:
 pass

cdef class PyClass:
 cdef Bar *bar

cdef PyClass_Init(Bar *b):
 result = PyClass()
 result.bar = b
 return result
</code></pre>

blocks|key|271041|text|在Cython+0.21中，可以使用@staticmethod装饰器来声明cdef方法。这允许静态创建者方法接受非Python参数：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|271042|cdef+extern+from+"Foo.h":
++++cdef+cppclass+Bar:
++++++++pass

cdef+class+PyClass:
++++cdef+Bar+*bar

++++@staticmethod
++++cdef+create(Bar+*bar):
++++++++cdef+PyClass+pc+=+PyClass()
++++++++pc.bar+=+bar
++++++++return+pc|code-block|syntax|javascript|271043|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/cython/cython/blob/master/CHANGES.rst#021-2014-09-10^0|I|D|11|4|1|B|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@$9|X|A|Y|1|Z]]|E|$]]|$1|F|3|G|5|H|7|10|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

As of <a href="https://github.com/cython/cython/blob/master/CHANGES.rst#021-2014-09-10" rel="noreferrer">Cython 0.21</a> it has been possible to declare <code>cdef</code> methods with the <code>@staticmethod</code> decorator. This allows static creator methods that take non-Python arguments:

<pre><code>cdef extern from "Foo.h":
 cdef cppclass Bar:
 pass

cdef class PyClass:
 cdef Bar *bar

 @staticmethod
 cdef create(Bar *bar):
 cdef PyClass pc = PyClass()
 pc.bar = bar
 return pc
</code></pre>

<pre><code>cdef extern from "Foo.h":
 cdef cppclass Bar:
 pass

cdef class PyClass:
 cdef Bar *bar

 def __cinit__(self, Bar *b)
 bar = b
</code></pre>

This will always give me something like: 
 <code>Cannot convert Python object argument to type 'Bar *'</code>

Is there a way to accomplish this, or do I need to extract everything from a <code>Bar</code> object, create a Python equivalent, pass it in, then reconstruct it in <code>PyClass</code>?

Passing C++ pointer as argument into Cython function

Python

cdef extern from "Foo.h":    cdef cppclass Bar:        passcdef class PyClass:    cdef Bar *bar    def __cinit__(self, Bar *b)        bar = b这将总是给我一些类似的东西：Canno...

问将C++指针作为参数传递给Cython函数
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