Kristján Valur Jónsson wrote:

Bringing this in from python-dev, and http://bugs.python.org/issue10278

Summary: time.clock() means two different things on Windows and Unix. So, if you need to measure time across a blocking call in a portable way, you need to use time.time() (this fact is not documented). Time.time has its own problems though, such as low resolution (compared to time.clock on windows) and being susceptible to being adjusted by the user.

I proposed adding a time.wallclock() to address this issue, which would be the most suitable function for the job on any platform. The patch is an example implementation. Any thoughts? And yes, I acknowledge that the time module is complicated enough as it is :)

I'm not particularly keen on "wall_clock" as a name. The name suggests it should return something like "12:37:15". I prefer a name that tells you what you would use the function for: this is the right function to use for timers, so call it "timer".

The timeit module includes:

if sys.platform == "win32": # On Windows, the best timer is time.clock() default_timer = time.clock else: # On most other platforms the best timer is time.time() default_timer = time.time

(Aside: what about WinCE? Shouldn't it also use time.clock?)

and the timeit.Timer class takes an argument "timer" which defaults to default_timer, so there is precedent on the name.

+1 on a platform-dependent alias to time() or clock() +1 on calling it "timer" -0 on calling it "wall_clock"

On Mon, Nov 1, 2010 at 9:50 PM, Steven D'Aprano steve@pearwood.info wrote: ..

The timeit module includes:

if sys.platform == "win32":    # On Windows, the best timer is time.clock()    default_timer = time.clock else:    # On most other platforms the best timer is time.time()    default_timer = time.time

Doesn't this mean that the requested functionality is already available as

from timeit import default_timer

?

On 02/11/2010 03:38, Steven D'Aprano wrote:

Alexander Belopolsky wrote:

...

On Mon, Nov 1, 2010 at 9:50 PM, Steven D'Aprano steve@pearwood.info wrote: ..

...

The timeit module includes:

if sys.platform == "win32": # On Windows, the best timer is time.clock() default_timer = time.clock else: # On most other platforms the best timer is time.time() default_timer = time.time

Doesn't this mean that the requested functionality is already available as

from timeit import default_timer

?

Well, yes, it does, but:

(1) How many people would think to look in timeit for this function? Both you and Kristján were apparently surprised that it already exists, and I'd bet money that you weren't the only ones. timeit seems to be more of an application than a library (although I acknowledge the border between the two is fuzzy), and people don't think about using it as a library.

(2) The time module is the natural place to look for time-related functions. It would be nicer if timeit could import the default timer from time:

from time import timer as default_timer # or wall_clock if you prefer

(3) The default_timer is an implementation detail of timeit. It could change, or disappear, or be renamed. You'll note it isn't documented:

http://docs.python.org/library/timeit.html

(4) I started off thinking that we should just document timer (wall_clock) as an alias to one of time() or clock(), but I changed my mind. That's an implementation detail that we should be free to change in the future. For the sake of information hiding, we shouldn't promise that the timer will be one of time.clock() or time.time(). Who knows, maybe there are (or will be someday) supported platforms where neither choice is appropriate, and the timer needs to be something else?

+1

Kristján Valur Jónsson wrote:

Bringing this in from python-dev, and http://bugs.python.org/issue10278

Summary: time.clock() means two different things on Windows and Unix. So, if you need to measure time across a blocking call in a portable way, you need to use time.time() (this fact is not documented). Time.time has its own problems though, such as low resolution (compared to time.clock on windows) and being susceptible to being adjusted by the user.

I proposed adding a time.wallclock() to address this issue, which would be the most suitable function for the job on any platform. The patch is an example implementation. Any thoughts? And yes, I acknowledge that the time module is complicated enough as it is :)

You might want to look at the systimes.py module that comes with pybench (see Tools/pybench). This already provides a cross-platform way of accessing high accuracy timers for benchmarking and the like.

For obvious reasons this tries to measure run-time, though, and not elapsed time.

On Tue, 02 Nov 2010 12:50:57 +1100 Steven D'Aprano steve@pearwood.info wrote:

+1 on a platform-dependent alias to time() or clock() +1 on calling it "timer"

"time.timer()" is much too close to "time.time()".

Regards

Antoine.

On 02/11/2010 13:21, Floris Bruynooghe wrote:

On 2 November 2010 11:35, Antoine Pitrousolipsis@pitrou.net wrote:

...

On Tue, 02 Nov 2010 12:50:57 +1100 Steven D'Apranosteve@pearwood.info wrote:

...

+1 on a platform-dependent alias to time() or clock() +1 on calling it "timer"

"time.timer()" is much too close to "time.time()".

I'd agree with this. I'm actually +1 on the original time.wallclock(), wall time is a common concept, so having the word "wall" in it's api seems very natural to me. .walltime() would probably work as well.

Regards Floris

I beg to differ. Seeing "wall clock" just confused me - my reaction was what the ..... is he talking about? Even when I understood it, it didn't seem a very appropriate name - I would have found something like "system clock" or "system time" more intelligible. Whereas "timer" is a very familiar concept (in computing, and in life in general). And I think most people are familiar with time.time(), so will recognize that time.timer() is something different. Though I agree it would be better if the names were more different. Best wishes Rob Cliffe

On Nov 2, 2010, at 11:02 AM, spir wrote:

Imo, "timer" is exactly the proper term -- the issue due to proximity with "time" is real, but far less important.

How about "stopwatch"

James

On 02/11/2010 15:35, Antoine Pitrou wrote:

On Tue, 2 Nov 2010 16:02:47 +0100 spirdenis.spir@gmail.com wrote:

...

Imo, "timer" is exactly the proper term

I'm not sure it's the proper term. A timer is often a countdown with a callback. See for example threading.Timer and signal.setitimer.

...

the issue due to proximity with "time" is real, but far less important.

I think it would be too easy to use one instead of the other, and get strange semantics (both count in seconds but with slightly different characteristic).

Regards

Antoine.

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Well, how about "clock"? "time.clock()" seems quite evocative to me. Best wishes Rob Cliffe

On 2010-11-02 16:17, James Noble wrote:

On Nov 2, 2010, at 11:02 AM, spir wrote:

...

Imo, "timer" is exactly the proper term -- the issue due to proximity with "time" is real, but far less important.

How about "stopwatch"

With that name, I would expect a "proper" stopwatch object with "get", "start", "stop" and "reset" methods. Not just an alias for time.time or time.clock.

I wouldn't mind seeing such an object in the stdlib, but it is easy enough to define in terms of the function that is actually proposed. For example:

from time import timer # the new function

class stopwatch(object):

def __init__(self, t=0.0): self._value = t self._started = None

def get(self): s = self._started if s is not None: return self._value + timer() - s return self._value

def reset(self, t=0.0): self._value = t if self._started is not None: self._started = timer()

def is_running(self): return self._started is not None

def start(self): if self._started is None: self._started = timer()

def stop(self): s = self._started if s is not None: self._value += timer() - s self._started = None

value = property(get, reset, reset)

running = property(is_running, None, stop)

@running.setter def running(self, value): if value: if self._started is None: self._started = timer() else: s = self._started if s is not None: self._value += timer() - s self._started = None

Oh, and +1 for the proposed function - I don't really care what it's called.

- Jacob

2010/11/2 M.-A. Lemburg mal@egenix.com:

You might want to look at the systimes.py module that comes with pybench (see Tools/pybench). This already provides a cross-platform way of accessing high accuracy timers for benchmarking and the like.

For obvious reasons this tries to measure run-time, though, and not elapsed time.

I think MAL answered the naming question without even realising it:

time.elapsed_time(start_time=0)

Cheers, Nick.

On 2 November 2010 22:17, Nick Coghlan ncoghlan@gmail.com wrote:

2010/11/2 M.-A. Lemburg mal@egenix.com:

...

You might want to look at the systimes.py module that comes with pybench (see Tools/pybench). This already provides a cross-platform way of accessing high accuracy timers for benchmarking and the like.

For obvious reasons this tries to measure run-time, though, and not elapsed time.

I think MAL answered the naming question without even realising it:

time.elapsed_time(start_time=0)

I'm +1 on the functionality and either elapsed_time or wallclock is fine with me.

Perhaps the patch author should decide...

Michael

Cheers, Nick.

-- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia _______________________________________________ Python-ideas mailing list Python-ideas@python.org http://mail.python.org/mailman/listinfo/python-ideas

On 03/11/2010 02:41, Michael Foord wrote:

On 2 November 2010 22:17, Nick Coghlan <ncoghlan@gmail.com mailto:ncoghlan@gmail.com> wrote:

2010/11/2 M.-A. Lemburg <mal@egenix.com <mailto:mal@egenix.com>>:
> You might want to look at the systimes.py module that comes with
pybench
> (see Tools/pybench). This already provides a cross-platform way of
> accessing high accuracy timers for benchmarking and the like.
>
> For obvious reasons this tries to measure run-time, though, and not
> elapsed time.

I think MAL answered the naming question without even realising it:

time.elapsed_time(start_time=0)

I'm +1 on the functionality and either elapsed_time or wallclock is fine with me.

Perhaps the patch author should decide...

Michael

elapsed_time! Please! Hate wallclock. Rob Cliffe

Cheers,
Nick.

--
Nick Coghlan   | ncoghlan@gmail.com <mailto:ncoghlan@gmail.com>  
|   Brisbane, Australia
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