Skip to content

Latest commit

 

History

History
148 lines (100 loc) · 4.27 KB

NOTES.md

File metadata and controls

148 lines (100 loc) · 4.27 KB

Notes

Todos

  • change Date#format to Date#format_like or Date#formatted or something else - why? why not?
  • add underscore for space-padded e.g. _2 like 02 for zero-padded - why? why not?
  • fully adopt go reference date/time convention? why? why not?
  • add alternate usage with DateFormatter.new( spec ).format( date|time|nil ) - for performance ("precompiled" strftime strings) - why? why not?

Alternate Usage - DateFormatter?

The slow part of using this gem is generating the format string from the example, if you want to reuse a format multiple times, you can do so by creating and reusing a DateFormatter

f = DateFormatter.new("DD/MM/YY")     # or using a golang-style "01/02/06" format string
f.format(Date.today)   #=> "06/11/18"
f.format(Time.now)     #=> "06/11/18"

Go Date / Time Formatter - Reference Date / Time?

I'd say go is pretty on target using an (unambigious) reference date. From the Rosseta stone sample:

 time.Now().Format("2006-01-02"))
 time.Now().Format("Monday, January 2, 2006")

That would be in ruby's date-formatter:

 Time.now.format("YYYY-MM-DD")
 Time.now.format("Monday, January 2, 2006")

Still kind of undecided if it is worth to reserve 1, 01, etc. for months and 2, 02, etc. for days and 3, 03, etc. for hours and 4, 04, for minutes and 5, 05, etc. for seconds and so on. For now you can write:

Time.now.format("Friday, February 4, 2020")

and it works too in Ruby's date formatter (but NOT using Golang's time format). In Golang you always MUST use the Monday, January 2, 2006 15:04:05 -7:00 reference date that you can supposedly learn and keep in memory by using the 0-1-2-3-4-5-6-7 trick. 0 = Monday, 1 = January, 2 = Day 2, 3 = Hour 15, 4 = Minute 4, 5 = Second 5, 6 = Year 2006, 7 = Timezone -7:00 (MST). Anyone has any opinions? Pro or contra?

The reference date is Jan 2, 2006 at 3:04:05 PM MST, which can be remembered as 1 2 3 4 5 6 -7.

I realize that remembering the reference date is not the easy part, but I think it's easier than remembering all the strftime format strings

Supported formats:

  • Year: 2006 and 06 (but not Ruby's %c for the century)
  • Month: January, JANUARY, Jan, JAN, 1, and 01, but not " 1" for space padding
  • Day: 2, 02, 002 (for day of year), Monday, MONDAY, Mon, MON, but not " 2" for space padding
  • Hour: 15, 3, pm, PM
  • Minute: 04
  • Second: 05, 05.000 for milliseconds and 05.000000 and 05.000000000
  • Time Zone: -7000, -07:00, -07:00:00, MST

The reference time used in the layouts is the specific time:

Mon Jan 2 15:04:05 MST 2006

which is Unix time 1136239445. Since MST is GMT-0700, the reference time can be thought of as

01/02 03:04:05PM '06 -0700

More:

See source https://golang.org/src/time/format.go

Alternatives

date_by_example https://rubygems.org/gems/date_by_example, Source: https://github.com/noelrappin/date_by_example

class ExampleFormatter
  attr_accessor :reference

  def initialize(reference)
    @reference = reference
    @format_string = nil
  end

  FORMATS = {
    ".000000000" => ".9N",
    "-07:00:00" => "%::z",
    ".000000" => ".%6N",
    "January" => "%B",
    "JANUARY" => "%^B",
    "Monday" => "%A",
    "MONDAY" => "%^A",
    "-07:00" => "%:z",
    "-7000" => "%z",
    "2006" => "%Y",
    ".000" => ".%L",
    "002" => "%j",
    "Jan" => "%b",
    "JAN" => "%^b",
    "Mon" => "%a",
    "MON" => "%^a",
    "MST" => "%Z",
    "15" => "%H",
    "06" => "%y",
    "01" => "%m",
    "02" => "%d",
    "03" => "%I",
    "PM" => "%p",
    "pm" => "%P",
    "04" => "%M",
    "05" => "%S",
    "1" => "%-m",
    "2" => "%-e",
    "3" => "%l"}.freeze

  FORMAT_MATCHER = Regexp.union(FORMATS.keys)

  def format_string
    @format_string ||= reference.gsub(FORMAT_MATCHER, FORMATS)
  end

  def format(date)
    date.strftime(format_string)
  end
end

string_formatted_date https://rubygems.org/gems/string_formatted_date, Source: https://github.com/TheLarkInn/string_formatted_date

date_molder https://rubygems.org/gems/date_molder, Source: https://github.com/gregolsen/date_molder

stamp https://rubygems.org/gems/stamp, Source: https://github.com/jeremyw/stamp

Date Formatting in Other Languages

See the Rosetta Stone Date Format page https://www.rosettacode.org/wiki/Date_format