millisec in strin representation of Time

[Joel VanderWerf]

Is there a way to use Time#strftime to generate a string that contains
milliseconds, and to do so in such a way that Time.parse understands it?

In other words, a value of ms_format that makes this work:

t_now = Time.at(1125180070.216)
diff = Time.parse(t_now.strftime(ms_format)) - t_now
diff.abs < 0.001 # ==> true

The default format does not represent milliseconds, so the diff can be
up to 1.0:

default_format = "%a %b %d %H:%M:%S %Z %Y"
t_now = Time.at(1125180070.216)
diff = Time.parse(t_now.strftime(default_format)) - t_now
p diff.abs # => 0.216

 

[James Edward Gray II]

Is there a way to use Time#strftime to generate a string that contains
milliseconds, and to do so in such a way that Time.parse
understands it?

In other words, a value of ms_format that makes this work:

t_now = Time.at(1125180070.216)
diff = Time.parse(t_now.strftime(ms_format)) - t_now
diff.abs < 0.001 # ==> true

The default format does not represent milliseconds, so the diff can be
up to 1.0:

default_format = "%a %b %d %H:%M:%S %Z %Y"
t_now = Time.at(1125180070.216)
diff = Time.parse(t_now.strftime(default_format)) - t_now
p diff.abs # => 0.216

This may not exactly answer your question, but you you parse with
strptime() instead?

James Edward Gray II

 

[Tanaka Akira]

Time.parse works via ParseDate.parsedate, and that, in turn, passes all the
heavy lifting to Date._parse. Date._parse, nifty bit of code that it is,
does parse out fractional seconds. However, parsedate doesn't look for the
fractional seconds, so they get lost in the conversion back to a Time object.

I see. I modified time.rb to use Date._parse directly.

 

[Joel VanderWerf]

I see. I modified time.rb to use Date._parse directly.

Works perfectly. Many thanks to both of you, Kirk and Tanaka!

 

[Joel VanderWerf]

Kirk Haines wrote:
...

class Time
class << Time
alias arse_old arse
def parse(date, now=Time.now)
t = parse_old(date,now)
d = Date._parse(date)
t += d[:sec_fraction].to_f if d.has_key? :sec_fraction t
end
end
end

If the _date_ arg doesn't have fractional seconds, then parse still
needs to return t.

 

[Andrew S. Townley]

Hi folks,

Did I miss something or did someone actually answer this part of the
question?

Is there a way to use Time#strftime to generate a string that contains
milliseconds,

I found myself hitting this same thing on Saturday (kinda ironic that
was when the original post was sent to the list). What I want to do is
something similar to the Java SimpleDateFormat where you can do
something like: yyyy-MM-dd HH:mm:ss.SSS z

I looked at the implementation of strftime in the ruby library and
there's some unused letters for %, however what I want is to be able to
specify the precision at the same time. I had considered hacking the
implementation of strftime and sending it to the list, but I hadn't
gotten there yet. I don't want to have to just do something like:

"%d" % (time.usec / (10*precision))

if I can avoid it. Before I go off and implement something silly, does
anyone have any ideas?

Thanks in advance,

ast

Kirk Haines wrote:
...

class Time
class << Time
alias arse_old arse
def parse(date, now=Time.now)
t = parse_old(date,now)
d = Date._parse(date)
t += d[:sec_fraction].to_f if d.has_key? :sec_fraction t
end
end
end

If the _date_ arg doesn't have fractional seconds, then parse still
needs to return t.

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[Joel VanderWerf]

Hi folks,

Did I miss something or did someone actually answer this part of the
question?

No, only the parsing side of the question was discussed.