Why is Ruby's Date class automatically loaded but DateTime is not?

Question

Using IRB, why are the Date & Time classes automatically loaded, but DateTime is not? I have to require 'date', this does not make sense to me because I thought that both Date and DateTime were using the standard library 'date'?

ruby-1.9.2-p290 :001 > Date
 => Date
ruby-1.9.2-p290 :002 > Time
 => Time
ruby-1.9.2-p290 :003 > DateTime
NameError: uninitialized constant Object::DateTime
    from (irb):3
    from /Users/kamilski81/.rvm/rubies/ruby-1.9.2-p290/bin/irb:16:in `<main>'
ruby-1.9.2-p290 :004 > require 'date'
 => true
ruby-1.9.2-p290 :005 > require 'date'
 => false
ruby-1.9.2-p290 :006 > DateTime
 => DateTime

`Date` has never been loaded automatically, you, or more likely `irb`, probably loads it, or loads something that in turn loads it. — Theo, Mar 14 '12 at 19:09
`Date` is not really loaded automatically, take a look at this [question](http://stackoverflow.com/a/11633934/52499). — x-yuri, May 14 '14 at 11:52

score 47 · Answer 1 · answered Jul 26 '13 at 19:25

In IRB, include this line: require 'date' then you will be able to use DateTime.

irb(main):000:0> DateTime.class
NameError: uninitialized constant DateTime
        from (irb):0
        from /path/to/ruby/irb:12:in '(main)'
irb(main):001:0> require 'date'
=> true
irb(main):002:0> DateTime.class
=> Class

Nomis · Answer 2 · 2016-04-18T13:06:31.747

4

Worked for me when first initializing with require 'date'.

edited Apr 18 '16 at 13:06

answered Apr 18 '16 at 13:00

Nomis

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Kamilski81 · Accepted Answer · 2012-03-14T19:03:34.853

1

Being a little more curious, I tried:

$ ruby -e 'puts DateTime.class'
-e:1:in `<main>': uninitialized constant Object::DateTime (NameError)
[~, kamilski81@mac]
$ ruby -e 'puts Date.class'
-e:1:in `<main>': uninitialized constant Object::Date (NameError)
$ ruby -e 'puts Time.class'
Class

So it makes me think that it's an irb issue that automatically loads 'date'.

edited Mar 14 '12 at 19:03

answered Mar 14 '12 at 15:34

Kamilski81

14,409
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Please append this to your original question and delete this answer. – the Tin Man Mar 14 '12 at 17:24

Why is Ruby's Date class automatically loaded but DateTime is not?

3 Answers3

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