Setting cdef variables from PyObject properties en masse

[Serdar Yegulalp]

I have functions that take in an Python object and set the various properties to typed equivalents, e.g.:

cdef int x = pyobject.x, y=pyobject.y, z=pyobject.z

This is done to allow any future manipulations of the variable to be done as purely in C as possible.

Is there a more efficient way to set a whole slew of these at once, rather than using the construction shown above?

[Robert Bradshaw]

I might write it in multiple lines to be clearer, e.g. 

cdef int x, y, z

x, y, z = pyobject.x, pyobject.y, pyobject.z

You could alternatively fore pyobject to be a Python object, or write a struct that has the relevant members and write helpers that did the unpacking (and packing if need be), e.g.

cdef struct c_members_struct:

    int x

    int y

    int z

cdef [inline] c_members_struct extract_c_members(pyobject):

    cdef c_members_struct c_members

    c_members.x = pyobject.x

    c_members.y = pyobject.y

    c_members.z = pyobject.z

    return c_members

or, if the attributes happen to align exactly, 

cdef c_members_struct c_members = pyobject.__dict__

You should also look at whether all members need to be in C variables, or only a couple accesses dominate the computation. Profile, profile, profile. 

- Robert