CODEWITHSUNDEEP
pythonc++cython
Carmellose
Carmellose

Reputation: 5087

Cython extension types attributes misunderstanding

I'm trying to grant python access for a member inside a cython class. The member type is basic (e.g. int or float)

As I read in the documentation, you can use properties to give access to the underlying C++ member:

cdef class myPythonClass:

   # grant access to myCppMember thanks to myMember
   property myMember:
      def __get__(self):
        return self.thisptr.myCppMember # implicit conversion
      # would somehow be the same logic for __set__ method

Now this works.

However, as far as I understand, for basic types you can just use extension types. In this case, you make the member public to make it accessible and/or writable. You don't need properties: 

 cdef class myPythonClass:
    cdef public int myCppMember # direct access to myCppMember

But when I use this second option, it does not work. The variable is never updated. Is there something I'm missing or I did not fully understood?

Thanks for you input.

Upvotes: 1

Views: 744

Answers (1)

Saullo G. P. Castro
Saullo G. P. Castro

Reputation: 59005

You already found the solution, using property is the way to go.

A public attribute can be accessed outside a class method, while a private attributes can only be used by the class methods.

But even public attributes defined at the C++ level cannot be accessed from Python. And exposing either a private or a public attribute using property will make it available to Python.

Upvotes: 1

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