[Python-Dev] datetime.timedelta total_microseconds

[Paul Ganssle]

I'm still with Alexander on this. I see functions like total_X as
basically putting one of the arguments directly in the function name -
it should be `total_duration(units)`, not `total_units()`, because all
of those functions do the same thing and only differ in the units they use.

But Alexander's approach of "divide it by the base unit" is /even more
general/ than this, because it allows you to use non-traditional units
like weeks (timedelta(days=7)) or "two-day periods" or whatever you
want. If you use this idiom a lot and want a simple "calculate the
total" function, this should suffice:

def total_duration(td, *args, **kwargs):
    return td / timedelta(*args, **kwargs)

Then you can spell "x.total_microseconds()" as:

total_duration(x, microseconds=1)

Or you can write it like this:

def total_duration(td, units='seconds'):
    return td / timedelta(**{units: 1})

In which case it would be spelled:

total_duration(x, units='microseconds')

I don't see there being any compelling reason to add a bunch of methods
for a marginal (and I'd say arguable) gain in aesthetics.

On 2/15/19 4:48 PM, Chris Barker via Python-Dev wrote:
> On Fri, Feb 15, 2019 at 11:58 AM Rob Cliffe via Python-Dev
> <python-dev at python.org <mailto:python-dev at python.org>> wrote:
>
>     A function with "microseconds" in the name IMO misleadingly
>     suggests that it has something closer to microsecond accuracy than
>     a 1-second granularity.
>
>
> it sure does, but `delta.total_seconds()` is a float, so ms accuracy
> is preserved.
>
> However, if you DO want a "timedelta_to_microseconds" function, it
> really should use the microseconds field in the timedelta object. I
> haven't thought it through, but it makes me nervous to convert to
> floating point, and then back again -- for some large values of
> timedelta some precision may be lost.
>
> Also:
>
>> _MICROSECONDS_PER_SECOND = 1000000
>
> really? why in the world would you define a constant for something
> that simple that can never change? (and probably isn't used in more
> than one place anyway
>  
> As Alexander pointed out the canonical way to spell this would be:
>
> delta / timedelta(microseconds=1)
>
> but I think that is less than obvious to the usual user, so I think a:
>
> delta.total_microseconds()
>
> would be a reasonable addition.
>
> I know I use .totalseconds() quite a bit, and would not want to have
> to spell it:
>
> delta / timedelta(seconds=1)
>
> (and can't do that in py2 anyway)
>
> -CHB
>
> -- 
>
> Christopher Barker, Ph.D.
> Oceanographer
>
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