MemoryViews and Garbage Collection in Python

Question

Basically:

If I declare a bytearray somewhere:

arr = bytearray(somestr)

Then create a memoryview of it:

view = memoryview(arr)

Can I be sure that for as long as I have a reference to the view object somewhere, that the bytearray will remain?

i.e:

def foo():
    arr = bytearray("hello world")
    return memoryview(arr)

view = foo()

Will garbage collection ever remove the original bytearray? Or does this count as a reference?

Answer 1

It counts as a reference. However you can call release() on the view to remove that reference:

>>> class A(bytes):
...     def __del__(self):print('called')
... 
>>> a =A()
>>> m = memoryview(a)
>>> del a
>>> m
<memory at 0x7fddcb00a288>
>>> len(m)
0
>>> m.release()
called

Note that you can access the underlying object from the view using the obj attribute.

In generaly, anything that is not described explicitly as a weak reference holds an actual reference. In memory-managed languages that's the default.