Ben Finney ben+pyt...@benfinney.id.au writes:
Gregory Ewing greg.ew...@canterbury.ac.nz writes:
Roy Smith wrote:
It looks to me like he's trying to implement a classic Gang of Four
singleton pattern.
Which I've never really seen the point of in Python, or any other
language for that
On 2/13/14 4:00 AM, Piet van Oostrum wrote:
Ben Finney ben+pyt...@benfinney.id.au writes:
Gregory Ewing greg.ew...@canterbury.ac.nz writes:
Roy Smith wrote:
It looks to me like he's trying to implement a classic Gang of Four
singleton pattern.
Which I've never really seen the point of in
On Thu, Feb 13, 2014 at 10:50 PM, Ned Batchelder n...@nedbatchelder.com wrote:
I still don't see it. To convince me that a singleton class makes sense,
you'd have to explain why by virtue of the class's very nature, it never
makes sense for there ever to be more than one of them.
There's a
In article mailman.6834.1392292646.18130.python-l...@python.org,
Chris Angelico ros...@gmail.com wrote:
On Thu, Feb 13, 2014 at 10:50 PM, Ned Batchelder n...@nedbatchelder.com
wrote:
I still don't see it. To convince me that a singleton class makes sense,
you'd have to explain why by
On 02/13/2014 03:50 AM, Ned Batchelder wrote:
On 2/13/14 4:00 AM, Piet van Oostrum wrote:
Ben Finney ben+pyt...@benfinney.id.au writes:
Gregory Ewing greg.ew...@canterbury.ac.nz writes:
Roy Smith wrote:
It looks to me like he's trying to implement a classic Gang of Four
singleton pattern.
In article mailman.6850.1392313443.18130.python-l...@python.org,
Ethan Furman et...@stoneleaf.us wrote:
Say you have a class that represents serial ports or your computer. You
should get the same object every time you ask
for SerialPort(2).
Why? Certainly, you should get objects which
On 02/13/2014 09:57 AM, Roy Smith wrote:
In article mailman.6850.1392313443.18130.python-l...@python.org,
Ethan Furman et...@stoneleaf.us wrote:
Say you have a class that represents serial ports or your computer. You
should get the same object every time you ask
for SerialPort(2).
Why?
In article mailman.6852.1392317509.18130.python-l...@python.org,
Ethan Furman et...@stoneleaf.us wrote:
On 02/13/2014 09:57 AM, Roy Smith wrote:
In article mailman.6850.1392313443.18130.python-l...@python.org,
Ethan Furman et...@stoneleaf.us wrote:
Say you have a class that represents
On 13 February 2014 20:00, Piet van Oostrum p...@vanoostrum.org wrote:
Ben Finney ben+pyt...@benfinney.id.au writes:
Make that “somewhere” a module namespace, and you effectively have a
Singleton for all practical purposes. So yes, I see the point of it; but
we already have it built in :-)
On Fri, Feb 14, 2014 at 6:03 AM, Roy Smith r...@panix.com wrote:
In article mailman.6852.1392317509.18130.python-l...@python.org,
Ethan Furman et...@stoneleaf.us wrote:
You mean use the Borg pattern instead of the Singleton pattern? As far as I
can tell they are two shades of the same
On Fri, Feb 14, 2014 at 2:24 AM, Roy Smith r...@panix.com wrote:
In article mailman.6834.1392292646.18130.python-l...@python.org,
Chris Angelico ros...@gmail.com wrote:
On Thu, Feb 13, 2014 at 10:50 PM, Ned Batchelder n...@nedbatchelder.com
wrote:
I still don't see it. To convince me that
On 2014-02-13 20:03, Chris Angelico wrote:
On Fri, Feb 14, 2014 at 2:24 AM, Roy Smith r...@panix.com wrote:
In article mailman.6834.1392292646.18130.python-l...@python.org,
Chris Angelico ros...@gmail.com wrote:
On Thu, Feb 13, 2014 at 10:50 PM, Ned Batchelder n...@nedbatchelder.com
wrote:
On Fri, Feb 14, 2014 at 8:13 AM, Robert Kern robert.k...@gmail.com wrote:
We don't use `is None` instead of `== None` for the speed. We use it for
robustness. We don't want arbitrary __eq__()s to interfere with our sentinel
tests. If None weren't a singleton that we could use as such a
On 2014-02-13, Roy Smith r...@panix.com wrote:
I envision SerialPort being a thin layer on top of a bunch of
OS-specific system calls to give them a pythonic interface.
Yep, that's pretty much what pyserial is
http://pyserial.sourceforge.net/
Things like is_shutdown() and set_bit_rate()
Steven D'Aprano wrote:
On Wed, 12 Feb 2014 23:04:32 +1300, Gregory Ewing wrote:
If you really want to make sure nobody creates another instance by
accident, delete the class out of the namespace after instantiating it.
That does not work. It is trivial to get the type from an instance:
I
Steven D'Aprano wrote:
Of course it can happen by accident. It's happened to me, where I've
accidentally called NoneType() (which raises, rather than returning a new
instance).
Well, unlikely to happen by accident, then.
--
Greg
--
https://mail.python.org/mailman/listinfo/python-list
Ethan Furman wrote:
Say you have a class that represents serial ports or your computer. You
should get the same object every time you ask for SerialPort(2).
No, you shouldn't ask for SerialPort(2) at all, you should
call get_serial_port(2). Then you won't be fooled into
thinking that you're
Roy Smith wrote:
It looks to me like he's trying to implement a classic Gang of Four
singleton pattern.
Which I've never really seen the point of in Python,
or any other language for that matter. Just create
one instance of the class during initialisation,
put it in a global somewhere, and use
Gregory Ewing greg.ew...@canterbury.ac.nz writes:
Roy Smith wrote:
It looks to me like he's trying to implement a classic Gang of Four
singleton pattern.
Which I've never really seen the point of in Python, or any other
language for that matter. Just create one instance of the class
In article mailman.6750.1392199807.18130.python-l...@python.org,
Ben Finney ben+pyt...@benfinney.id.au wrote:
Gregory Ewing greg.ew...@canterbury.ac.nz writes:
Roy Smith wrote:
It looks to me like he's trying to implement a classic Gang of Four
singleton pattern.
Which I've never
On Wednesday, February 12, 2014 7:48:51 AM UTC+2, Dave Angel wrote:
Perhaps if you would state your actual goal, we could judge
whether this code is an effective way to accomplish
it.
DaveA
Thanks!
There is no specific goal, i am in process of building pattern knowledge
in python by
There is another one.
Once object passes through singletonizator
there wont be any other object than first one.
Then object constructor can freely be used in every place
of code.
Curious if there could be any impact and applicability
of this to builtin types.
p.s. learned today that
mistake, object constructor - to class constructor
--
https://mail.python.org/mailman/listinfo/python-list
On 12/02/2014 17:50, Asaf Las wrote:
On Wednesday, February 12, 2014 7:48:51 AM UTC+2, Dave Angel wrote:
Perhaps if you would state your actual goal, we could judge
whether this code is an effective way to accomplish
it.
DaveA
Thanks!
There is no specific goal, i am in process of
On 2/12/14 12:50 PM, Asaf Las wrote:
On Wednesday, February 12, 2014 7:48:51 AM UTC+2, Dave Angel wrote:
Perhaps if you would state your actual goal, we could judge
whether this code is an effective way to accomplish
it.
DaveA
Thanks!
There is no specific goal, i am in process of
Asaf Las wrote:
There is another one.
Once object passes through singletonizator
there wont be any other object than first one.
Then object constructor can freely be used in every place
of code.
You're still making things far more complicated
than they need to be.
*Why* do you want to be
On 02/11/2014 09:34 PM, Asaf Las wrote:
playing a bit with subject.
pros and cons of this approach? did i create bicycle again? :-)
I always thought sticking an object in a module is the simplest form of
singleton.
--
https://mail.python.org/mailman/listinfo/python-list
On 13 February 2014 08:34, Ned Batchelder n...@nedbatchelder.com wrote:
On 2/12/14 12:50 PM, Asaf Las wrote:
On Wednesday, February 12, 2014 7:48:51 AM UTC+2, Dave Angel wrote:
Perhaps if you would state your actual goal, we could judge
whether this code is an effective way to
On Wednesday, February 12, 2014 8:57:09 PM UTC+2, Mark Lawrence wrote:
For more data on python patterns search for
python+patterns+Alex+Martelli. He's forgotten more on the subject than
many people on this list will ever know :)
My fellow Pythonistas, ask not what our language can do
On Wednesday, February 12, 2014 11:34:34 PM UTC+2, Ned Batchelder wrote:
Not all patterns are useful. Just because it's been enshrined in the
GoF patterns book doesn't mean that it's good for Python.
Yes, i understand up to some extend usefulness of patterns.
i did not read the GoF book.
On Wednesday, February 12, 2014 11:57:02 PM UTC+2, Gregory Ewing wrote:
If you want to hide the distinction between using
call syntax and just accessing a global, then
export a function that returns the global instance.
That function can even lazily create the instance
the first time it's
In article 9785668d-6bea-4382-8a0c-c1258f2e2...@googlegroups.com,
Asaf Las roeg...@gmail.com wrote:
On Wednesday, February 12, 2014 7:48:51 AM UTC+2, Dave Angel wrote:
Perhaps if you would state your actual goal, we could judge
whether this code is an effective way to accomplish
it.
On Wed, 12 Feb 2014 23:04:32 +1300, Gregory Ewing wrote:
Roy Smith wrote:
It looks to me like he's trying to implement a classic Gang of Four
singleton pattern.
Which I've never really seen the point of in Python, or any other
language for that matter. Just create one instance of the class
Steven D'Aprano st...@pearwood.info writes:
On Wed, 12 Feb 2014 23:04:32 +1300, Gregory Ewing wrote:
If you really want to make sure nobody creates another instance by
accident, delete the class out of the namespace after instantiating
it.
That does not work. It is trivial to get the
On Thu, 13 Feb 2014 14:07:55 +1100, Ben Finney wrote:
Steven D'Aprano st...@pearwood.info writes:
On Wed, 12 Feb 2014 23:04:32 +1300, Gregory Ewing wrote:
If you really want to make sure nobody creates another instance by
accident, delete the class out of the namespace after instantiating
On Thu, Feb 13, 2014 at 3:24 PM, Steven D'Aprano st...@pearwood.info wrote:
Of course it can happen by accident. It's happened to me, where I've
accidentally called NoneType() (which raises, rather than returning a new
instance).
It does in 2.7, yes, but not in 3.4:
type(None)() is None
True
there is error should assign weakref to class static member otherwise __del__
will never be called.
--
https://mail.python.org/mailman/listinfo/python-list
In article mailman.6728.1392183929.18130.python-l...@python.org,
Dave Angel da...@davea.name wrote:
Asaf Las roeg...@gmail.com Wrote in message:
playing a bit with subject.
pros and cons of this approach? did i create bicycle again? :-)
class myclass(object):
class_instance
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