Bad Implementation of Time.strptime
According to the documentation,
Time.strptime "parses +date+ using
Date._strptime and converts it to a Time object." However this conversion is extremely naive, using only certain fields return by
Date._strptime and ignoring the rest (for example
This creates confusing and inconsistent behavior when compared to
puts Date.strptime('201418', "%Y%U") => 2014-05-04 puts DateTime.strptime('201418', "%Y%U") => 2014-05-04T00:00:00+00:00 puts Time.strptime('201418', "%Y%U") => 2014-01-01 00:00:00 -0500
Updated by nobu (Nobuyoshi Nakada) about 8 years ago
I guess the OP expects
%U not to be ignored.
diff --git a/lib/time.rb b/lib/time.rb index 3728fef..ec45767 100644 --- a/lib/time.rb +++ b/lib/time.rb @@ -194,13 +194,18 @@ class Time LeapYearMonthDays = [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31] # :nodoc: CommonYearMonthDays = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31] # :nodoc: - def month_days(y, m) + def month_days_of_year(y) if ((y % 4 == 0) && (y % 100 != 0)) || (y % 400 == 0) - LeapYearMonthDays[m-1] + LeapYearMonthDays else - CommonYearMonthDays[m-1] + CommonYearMonthDays end end + private :month_days_of_year + + def month_days(y, m) + month_days_of_year(y)[m-1] + end private :month_days def apply_offset(year, mon, day, hour, min, sec, off) @@ -432,7 +437,34 @@ class Time else year = d[:year] year = yield(year) if year && block_given? - t = make_time(date, year, d[:mon], d[:mday], d[:hour], d[:min], d[:sec], d[:sec_fraction], d[:zone], now) + mon = d[:mon] + mday = d[:mday] + unless mon and mday + case + when (w = d[:wnum0]) # %U + range = 0..53 + mday = +1 + when (w = d[:wnum1]) # %W + range = 0..53 + mday = +2 + when (w = d[:cweek]) # %V + range = 1..53 + mday = -6 + end + if mday + raise ArgumentError, "invalid date" unless range.cover?(w) + t = make_time(date, year, 1, 1, nil, nil, nil, nil, d[:zone], now) + mday += w * 7 - t.wday + if w = d[:wday] || d[:cwday] + mday += w + end + month_days_of_year(t.year).each_with_index do |n, m| + break mon = m+1 if mday <= n + mday -= n + end + end + end + t = make_time(date, year, mon, mday, d[:hour], d[:min], d[:sec], d[:sec_fraction], d[:zone], now) end t end
Updated by silverhammermba (Max Anselm) about 8 years ago
Sorry for the unclear wording. I would expect that it behaves similar to
DateTime's implementation and to not ignore any fields returned by
Date._strptime. At the very least the documentation should reflect the fact that it will only use certain values when constructing the
The fact that
Date.strptime("201418", "%Y%U").to_time Time.strptime("201418", "%Y%U")
return different times is very surprising.
Updated by jeremyevans0 (Jeremy Evans) almost 3 years ago
I tried updating the patch to apply to the master branch (it is attached). It doesn't appear to handle
str = Time.local(2019, 1, 30).strftime('%w %W %Y') # => "3 04 2019" Date.strptime(str, '%w %W %Y') # => #<Date: 2019-01-30 ((2458514j,0s,0n),+0s,2299161j)> Time.strptime(str, '%w %W %Y') # => 2019-01-31 00:00:00 -0800
I think the approach I'm proposing in #14241 is simpler, by leaving the calculation to
Updated by jeremyevans (Jeremy Evans) over 2 years ago
- Status changed from Feedback to Closed
Applied in changeset git|a9d4f2d03c847ec1c89dc03a5076a9fa29ffa61f.
Support %U/%u/%W/%w/%V/%g/%G formats in Time.strptime
Most of these formats were documented as supported, but were not
actually supported. Document that %g and %G are supported.
If %U/%W is specified without yday and mon/mday are not specified,
then Date.strptime is used to get the appropriate yday.
If cwyear is specifier without the year, or cwday and cweek are
specified without mday and mon, then use Date.strptime and convert
the resulting value to Time, since Time.make_time cannot handle