On Thursday, 1 March 2018 22:44:59 UTC, Rob Gaddi wrote:
> On 03/01/2018 02:24 PM, Lawrence D’Oliveiro wrote:
> > On Thursday, March 1, 2018 at 6:44:39 PM UTC+13, Paul Rubin wrote:
> >> DOM trees are a classic example (see the various DOM modules in the
> >> Python stdlib). Non-leaf nodes have a
On Wednesday, 7 March 2018 06:43:10 UTC, Ooomzay wrote:
> On Tuesday, 6 March 2018 14:12:38 UTC, Peter Otten wrote:
> > Chris Angelico wrote:
> >
> > > On Tue, Mar 6, 2018 at 10:04 AM, Steven D'Aprano
> > > wrote:
> > >> # Later.
> > >
On Tuesday, 6 March 2018 14:12:38 UTC, Peter Otten wrote:
> Chris Angelico wrote:
>
> > On Tue, Mar 6, 2018 at 10:04 AM, Steven D'Aprano
> > wrote:
> >> # Later.
> >> if __name__ = '__main__':
> >> # Enter the Kingdom of Nouns.
> >
> > Don't you need a NounKingdomEnterer to do that for you?
On Monday, 5 March 2018 23:06:53 UTC, Steven D'Aprano wrote:
> On Mon, 05 Mar 2018 09:22:33 -0800, Ooomzay wrote:
> [...]
> > If you would like to have a shot at coding this without RAII, but
> > preserving the OO design, you will find that it is considerably
> >
On Monday, 5 March 2018 19:14:05 UTC, Paul Rubin wrote:
> Ooomzay writes:
> > If you want to use RAII objects then you will make sure you avoid
> > adding them to orphan cycles by design. If you don't know how to do
> > that then don't write applications that man
On Monday, 5 March 2018 17:58:40 UTC, Chris Angelico wrote:
> On Tue, Mar 6, 2018 at 4:53 AM, Ooomzay wrote:
> > On Monday, 5 March 2018 14:21:54 UTC, Chris Angelico wrote:
> >> On Tue, Mar 6, 2018 at 12:58 AM, Ooomzay wrote:
> >> > Here is my fixed example, i
On Monday, 5 March 2018 14:21:54 UTC, Chris Angelico wrote:
> On Tue, Mar 6, 2018 at 12:58 AM, Ooomzay wrote:
> > Here is my fixed example, if someone else could try it in CPython and
> > report back that would be interesting:-
> >
> > class RAIIFileAccess():
>
On Monday, 5 March 2018 16:47:02 UTC, Steven D'Aprano wrote:
> 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):
> >
On Monday, 5 March 2018 15:17:13 UTC, bartc wrote:
> On 05/03/2018 13:58, Ooomzay wrote:
> > On Monday, 5 March 2018 11:24:37 UTC, Chris Angelico wrote:
> >> On Mon, Mar 5, 2018 at 10:09 PM, Ooomzay wrote:
> >>> Here is an example of a composite resource
On Monday, 5 March 2018 14:36:30 UTC, Chris Angelico wrote:
> On Tue, Mar 6, 2018 at 1:25 AM, Ooomzay wrote:
> > Ahah... I see now you are running it from a shell so the exception is
> > staying in scope. We just need to include normal exception handling in the
> >
On Monday, 5 March 2018 13:59:35 UTC, Ooomzay wrote:
> On Monday, 5 March 2018 11:24:37 UTC, Chris Angelico wrote:
> > On Mon, Mar 5, 2018 at 10:09 PM, Ooomzay wrote:
> > > Here is an example of a composite resource using RAII:-
> > >
> > > class RAIIFileA
On Monday, 5 March 2018 11:24:37 UTC, Chris Angelico wrote:
> On Mon, Mar 5, 2018 at 10:09 PM, Ooomzay wrote:
> > Here is an example of a composite resource using RAII:-
> >
> > class RAIIFileAccess():
> > def __init__(self, fname):
> > print("%
On Sunday, 4 March 2018 23:56:09 UTC, Chris Angelico wrote:
> On Sun, Mar 4, 2018 at 10:37 PM, Ooomzay wrote:
> > Please consider the case of a composite resource: You need to implement
> > __enter__, __exit__ and track the open/closed state at every level in
> > your compo
On Monday, March 5, 2018 at 6:38:49 AM UTC, Mark Lawrence wrote:
> On 05/03/18 01:01, Ooomzay wrote:
> > On Sunday, 4 March 2018 23:57:24 UTC, Mark Lawrence wrote:
> >> On 04/03/18 02:28, Ooomzay wrote:
> >>> On Friday, 2 March 2018 15:37:25 UTC, Paul Moore wrote:
On Monday, 5 March 2018 01:11:43 UTC, Richard Damon wrote:
> On 3/4/18 6:55 PM, Ned Batchelder wrote:
> > On 3/4/18 5:25 PM, Ooomzay wrote:
> >> On Sunday, 4 March 2018 14:37:30 UTC, Ned Batchelder wrote:
> >>> Are you including cyclic references in your assertion
On Saturday, 3 March 2018 17:10:53 UTC, Dietmar Schwertberger wrote:
> CPython does *not* guarantee destruction when the object reference goes
> out of scope, even if there are no other references.
> I would very much appreciate such a deterministic behaviour, at least
> with CPython.
>
> I rec
On Sunday, 4 March 2018 23:55:33 UTC, Ned Batchelder wrote:
> On 3/4/18 5:25 PM, Ooomzay wrote:
> > On Sunday, 4 March 2018 14:37:30 UTC, Ned Batchelder wrote:
> >> Are you including cyclic references in your assertion that CPython
> >> behaves as you want?
> >
On Sunday, 4 March 2018 23:57:24 UTC, Mark Lawrence wrote:
> On 04/03/18 02:28, Ooomzay wrote:
> > On Friday, 2 March 2018 15:37:25 UTC, Paul Moore wrote:
> > [snip]
> >> def fn():
> >> for i in range(1):
> >>
On Sunday, 4 March 2018 15:24:08 UTC, Steven D'Aprano wrote:
> On Sun, 04 Mar 2018 03:37:38 -0800, Ooomzay wrote:
>
> > Please consider the case of a composite resource: You need to implement
> > __enter__, __exit__ and track the open/closed state at every level in
>
On Sunday, 4 March 2018 14:37:30 UTC, Ned Batchelder wrote:
> Are you including cyclic references in your assertion that CPython
> behaves as you want?
Yes. Because the only behaviour required for RAII is to detect and debug such
cycles in order to eliminate them. It is a design error/resource
On Sunday, 4 March 2018 03:00:13 UTC, Chris Angelico wrote:
> This thread is dead. The OP wants to wave a magic wand and say
> "__del__ is now guaranteed to be called immediately",
No "magic" required: Just one line change in the language reference will do it.
> without any explanation
The PEP
On Sunday, 4 March 2018 03:16:31 UTC, Paul Rubin wrote:
> Chris Angelico writes:
> > Yep, cool. Now do that with all of your smart pointers being on the
> > heap too. You are not allowed to use ANY stack objects. ANY. Got it?
>
> That's both overconstraining and not even that big a problem the
On Sunday, 4 March 2018 04:23:07 UTC, Steven D'Aprano wrote:
> [...]
> [This PEP] imposes enormous burdens on the maintainers of at least five
> interpreters (CPython, Stackless, Jython, IronPython, PyPy) all of which
> will need to be re-written to have RAII semantics guaranteed;
Not so:- CP
On Sunday, 4 March 2018 04:23:07 UTC, Steven D'Aprano wrote:
> On Sat, 03 Mar 2018 18:19:37 -0800, Ooomzay wrote:
>
> >> def function():
> >> x = open_resource()
> >> process(x)
> >> # and we're done with x now, but too lazy to
On Sunday, 4 March 2018 01:58:02 UTC, Gregory Ewing wrote:
> ooomzay wrote:
> > Well he was not telling you the whole story: RAII works just as well with
> > heap objects using smart pointers (unique_ptr and friends) which are a
> > closer
> > analogy to python obje
On Friday, 2 March 2018 15:37:25 UTC, Paul Moore wrote:
[snip]
> def fn():
> for i in range(1):
> with open(f"file{i}.txt", "w") as f:
> f.write("Some text")
>
> How would you write this in your RAII style - without leaving 10,000
> file descriptors op
On Saturday, 3 March 2018 23:52:34 UTC, Steven D'Aprano wrote:
> I know that laziness and hubris are programmer virtues, but there is
> still such a thing as *too much laziness*. RAII works in C++ where
> instances are allocated in the stack, but even there, if you have an
> especially long-liv
On Saturday, 3 March 2018 17:44:08 UTC, Chris Angelico wrote:
> On Sun, Mar 4, 2018 at 4:37 AM, Richard Damon
> > Yes, stack allocated object in C++ have a nice lifetime to allow RAII to
> > work, but it doesn't just work with stack allocated objects. A lot of RAII
> > objects are members of a c
On Saturday, 3 March 2018 17:16:14 UTC, Ned Batchelder wrote:
> On 3/2/18 10:36 AM, Paul Moore wrote:
> > Or (real Python):
> >
> > def fn():
> > for i in range(1):
> > with open(f"file{i}.txt", "w") as f:
> > f.write("Some text")
> >
> > How would y
On Friday, March 2, 2018 at 5:29:54 AM UTC, Rustom Mody wrote:
> Please excuse if this has been addressed above and/or its too basic:
> What's the difference between RAII and python's with/context-managers?
They address the same problem but I am claiming that RAII achieves this in a
significantly
On Friday, March 2, 2018 at 3:37:25 PM UTC, Paul Moore wrote:
> [...]
> RAII works in C++ (where it was initially invented) because it's used
> with stack-allocated variables that have clearly-defined and limited
> scope.
RAII also works with smart pointers, which are a closer analogue
to pyth
On Saturday, March 3, 2018 at 4:33:59 PM UTC, Michael Torrie wrote:
> On 03/03/2018 09:02 AM, ooomzay wrote:
> > I can assure you that RAII does what it says on the tin and is relied on in
> > many critical systems to release resources robustly ... given the
> > pre-re
On Friday, March 2, 2018 at 10:43:57 PM UTC, Steven D'Aprano wrote:
> On Fri, 02 Mar 2018 07:09:19 -0800, ooomzay wrote:
> [...]
> >> If you're going to *require* the programmer to explicitly del the
> >> reference:
> >>
> >> f =
On Friday, March 2, 2018 at 2:43:09 PM UTC, Chris Angelico wrote:
> On Sat, Mar 3, 2018 at 1:18 AM, ooomzay wrote:
> > On Friday, March 2, 2018 at 8:16:22 AM UTC, Paul Rubin wrote:[snip]
> >> controlling stuff like file handles
> >> with scopes (like with "with&
On Friday, March 2, 2018 at 4:35:41 AM UTC, Steven D'Aprano wrote:
> On Thu, 01 Mar 2018 16:26:47 -0800, ooomzay wrote:
>
> >> >> When does the destination file get closed?
> >> >
> >> > When you execute:-
> >> >
> >>
On Friday, March 2, 2018 at 1:59:02 AM UTC, Lawrence D’Oliveiro wrote:
> On Friday, March 2, 2018 at 1:03:08 PM UTC+13, ooo...@gmail.com wrote:
> > On Thursday, March 1, 2018 at 11:51:50 PM UTC, Lawrence D’Oliveiro wrote:
> >> On Friday, March 2, 2018 at 12:39:01 PM UTC+13, ooo...@gmail.com wrote:
On Friday, March 2, 2018 at 8:16:22 AM UTC, Paul Rubin wrote:[snip]
> controlling stuff like file handles
> with scopes (like with "with") is fine.
How does with work for non-trivial/composite objects that represent/reference
multiple resources or even a hierarchy of such objects where all the re
On Friday, March 2, 2018 at 12:22:13 AM UTC, MRAB wrote:
> On 2018-03-01 23:38, ooomzay wrote:
[Snip]
> > PEP343 requires two new methods: __enter__ & __exit__.
> > RIAA requires no new methods.
> >
> > RIAA resources are invariant: If you have a reference t
On Friday, March 2, 2018 at 12:14:53 AM UTC, Chris Angelico wrote:
> On Fri, Mar 2, 2018 at 11:07 AM, ooomzay wrote:
> > On Thursday, March 1, 2018 at 11:59:26 PM UTC, Chris Angelico wrote:
> >> On Fri, Mar 2, 2018 at 10:38 AM, ooomzay wrote:
> >> > def raii_ex
On Thursday, March 1, 2018 at 11:59:26 PM UTC, Chris Angelico wrote:
> On Fri, Mar 2, 2018 at 10:38 AM, ooomzay wrote:
> > def raii_example():
> >
> > src = RAIIFileAccess("src.txt", 'r')
> > dst = RAIIFileAccess("dst.txt", &#x
On Thursday, March 1, 2018 at 11:51:50 PM UTC, Lawrence D’Oliveiro wrote:
> On Friday, March 2, 2018 at 12:39:01 PM UTC+13, ooo...@gmail.com wrote:
> > class RAIIFileAccess():
> > '''File Access-like Resource using [RAII] idiom'''
> >
> > ...
> >
> > def __del__(self):
> >
On Thursday, March 1, 2018 at 12:15:57 AM UTC, Paul Rubin wrote:
> RAII is similar to Python's "with" statement. So it sounds like OP
> wants to replace one "malignant carbuncle" with another one.
I would like to understand why you think RAII is not substantially more
pythonic than "With". Bel
On Thursday, March 1, 2018 at 12:35:38 PM UTC, Richard Damon wrote:
> [snip]
> I disagree with the original complaint that these
> are always 'errors', if you know you have garbage collection, the
> allowance of cycles knowing they will still get cleaned up is a useful
> simplification if you do
On Wednesday, February 28, 2018 at 11:45:24 PM UTC, ooo...@gmail.com wrote:
> On Wednesday, February 28, 2018 at 11:02:17 PM UTC, Chris Angelico wrote:
> > On Thu, Mar 1, 2018 at 9:51 AM, ooomzay wrote:
> > [snip]
> > Taking a really simple situation:
> >
> > cla
On Wednesday, February 28, 2018 at 11:02:17 PM UTC, Chris Angelico wrote:
> On Thu, Mar 1, 2018 at 9:51 AM, ooomzay wrote:
> > Specification
> > =
> >
> > When the last reference to an object goes out of scope the intepreter must
> > synchronously
Informal Background
===
Python's lack of Deterministic Object Destruction semantics strikes me as very
unpythonic. This state of affairs spawns lengthy diatribes on __del__(), a
variety of specialised and onerous resource management solutions and malignant
carbuncles such as PEP
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