42 lines
1.3 KiB
Python
42 lines
1.3 KiB
Python
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from ctypes import c_void_p
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class CPointerBase:
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"""
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Base class for objects that have a pointer access property
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that controls access to the underlying C pointer.
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"""
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_ptr = None # Initially the pointer is NULL.
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ptr_type = c_void_p
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destructor = None
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null_ptr_exception_class = AttributeError
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@property
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def ptr(self):
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# Raise an exception if the pointer isn't valid so that NULL pointers
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# aren't passed to routines -- that's very bad.
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if self._ptr:
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return self._ptr
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raise self.null_ptr_exception_class(
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"NULL %s pointer encountered." % self.__class__.__name__
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)
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@ptr.setter
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def ptr(self, ptr):
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# Only allow the pointer to be set with pointers of the compatible
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# type or None (NULL).
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if not (ptr is None or isinstance(ptr, self.ptr_type)):
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raise TypeError("Incompatible pointer type: %s." % type(ptr))
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self._ptr = ptr
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def __del__(self):
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"""
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Free the memory used by the C++ object.
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"""
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if self.destructor and self._ptr:
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try:
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self.destructor(self.ptr)
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except (AttributeError, ImportError, TypeError):
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pass # Some part might already have been garbage collected
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