#11339: Illegal use of __deallocate__ in cython (pyx) code
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Reporter: gagern | Owner: drkirkby
Type: defect | Status: new
Priority: major | Milestone: sage-4.7
Component: porting | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Comment(by vbraun):
The documentation is fairly clear, you are only allowed to touch C data
structures in `__dealloc__`:
http://docs.cython.org/src/userguide/special_methods.html#finalization-
method-dealloc
Really, this shows the difference between the C++ and the Python object
model. In Python, executing constructors/destructors in derived classes is
optional and leaves a lot of freedom to the programmer. Because of the
garbage collection you can allocate resources wherever you want. By
comparison, C++ is very strict and essentially forces you to use RAII.
This is why there is no try/finally in C++. Which is why there is
necessarily some tension in Cython between C++ and Python object
instantiation/finalization.
Having said that, it seems like the cleanest solution would be if Cython
would also call the Python destructor `__del__` according to the normal
Python rules (why `__clear__`?). Then the Python and C++ object model
could just peacefully coexist. The lifetime of a cdef class would be
{{{
__cinit__() # always called
__init__() # not necessarily called for derived classes
... do something ...
__del__() # not necessarily called for derived classes
__dealloc__() # always called
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11339#comment:2>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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