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RFC: Proposal: Deterministic Object Destruction


On Sun, 04 Mar 2018 16:58:38 -0800, Ooomzay wrote:

> Here is an example of a composite resource using RAII:-
> 
> class RAIIFileAccess():
>     def __init__(self, fname):
>         print("%s Opened" % fname)
>     def __del__(self):
>         print("%s Closed" % fname)
> 
> class A():
>     def __init__(self):
>         self.res = RAIIFileAccess("a")
> 
> class B():
>     def __init__(self):
>         self.res = RAIIFileAccess("b")
> 
> class C():
>     def __init__(self):
>         self.a = A()
>         self.b = B()
>                  
> def main():
>     c = C()

Looking at that code, my major thought is  that there is far too much OO 
design, not enough simplicity.

Perhaps I'm missing something, but I have no idea what benefit there is 
in that style of code over:

with open('a') as a:
    with open('b') as b:
        process(a, b)

So long as you only process a or b inside the nested block, you are 
guaranteed that they will be open.

And unlike your RAII example, they will be closed when you exit, 
regardless of how many references to them you have, regardless of whether 
an exception occurs or not, regardless of whether there are cycles or 
whether they are globals or whether the interpreter is shutting down.

I think that at this point, you have convinced me that you want to impose 
enormous costs on all Python interpreters *and* Python developers, in 
order to allow you to write C++ code in Python rather than learn Pythonic 
idioms like the with statement.


I don't think this is a good tradeoff.


-- 
Steve