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comp.lang.ruby

Re: Date and DateTime on the Mac

John Joyce

8/20/2007 8:53:00 PM


On Aug 20, 2007, at 3:07 PM, Felix Windt wrote:

>> -----Original Message-----
>> From: Ronny [mailto:ro.naldfi.scher@gmail.com]
>> Sent: Monday, August 20, 2007 12:50 PM
>> To: ruby-talk ML
>> Subject: Date and DateTime on the Mac
>>
>> I have installed ruby for Mac OS/X. Strangely, the classes Date and
>> DateTime
>> are not known:
>>
>> NameError: uninitialized constant DateTime
>> from (irb):1
>>
>> At least some other classes (I tried File and Time) exist, so it is
>> not that the
>> installation were completely broken.
>>
>> What could be the problem here?
>>
>> Ronald
>>
>>
>
> Date/DateTime need to be required and aren't automatically loaded.
>
> require 'date'
> now = DateTime.now

It is part of the Ruby 'standard library' but you do still need to
require a library before using it.
If you are not sure if a method is available, that is, you don't know
if it has been required, use irb.
in irb try the method. Error message? then try require 'library_name'
and it will return true on success, false on failure.
If it returns false, you might have mistyped the name, or path to the
library.
4 Answers

Hassan Schroeder

8/20/2007 9:13:00 PM

0

On 8/20/07, John Joyce <dangerwillrobinsondanger@gmail.com> wrote:

> It is part of the Ruby 'standard library' but you do still need to
> require a library before using it.

Is this platform dependent? 'require' doesn't seem to be, er, required
on my SuSE system --

hassan@ceylon:~> ruby -v
ruby 1.8.6 (2007-03-13 patchlevel 0) [x86_64-linux]
hassan@ceylon:~> irb
irb(main):001:0> DateTime.now.to_s
=> "2007-08-20T14:14:31-07:00"
irb(main):002:0>

--
Hassan Schroeder ------------------------ hassan.schroeder@gmail.com

Gary Wright

8/20/2007 9:29:00 PM

0


On Aug 20, 2007, at 5:12 PM, Hassan Schroeder wrote:

> On 8/20/07, John Joyce <dangerwillrobinsondanger@gmail.com> wrote:
>
>> It is part of the Ruby 'standard library' but you do still need to
>> require a library before using it.
>
> Is this platform dependent? 'require' doesn't seem to be, er, required
> on my SuSE system --
>
> hassan@ceylon:~> ruby -v
> ruby 1.8.6 (2007-03-13 patchlevel 0) [x86_64-linux]
> hassan@ceylon:~> irb
> irb(main):001:0> DateTime.now.to_s
> => "2007-08-20T14:14:31-07:00"
> irb(main):002:0>

Be careful with irb. It has its own set of startup rules and
behaviors that
are slightly different than Ruby itself. Try:

ruby -e 'puts DateTime.now.to_s'

Ruby's startup behaviour can also be changed if the RUBYOPT environment
variable is set.

On my installation irb shows 451 classes defined at startup while the
Ruby
interpreter just shows 147 classes.

Hassan Schroeder

8/20/2007 9:45:00 PM

0

On 8/20/07, Gary Wright <gwtmp01@mac.com> wrote:

> Be careful with irb. It has its own set of startup rules and
> behaviors that are slightly different than Ruby itself. Try:
>
> ruby -e 'puts DateTime.now.to_s'

Aha, that fails. Good to know -- thanks for the clarification.

--
Hassan Schroeder ------------------------ hassan.schroeder@gmail.com

John Joyce

8/20/2007 10:40:00 PM

0


On Aug 20, 2007, at 4:29 PM, Gary Wright wrote:

>
> On Aug 20, 2007, at 5:12 PM, Hassan Schroeder wrote:
>
>> On 8/20/07, John Joyce <dangerwillrobinsondanger@gmail.com> wrote:
>>
>>> It is part of the Ruby 'standard library' but you do still need to
>>> require a library before using it.
>>
>> Is this platform dependent? 'require' doesn't seem to be, er,
>> required
>> on my SuSE system --
>>
>> hassan@ceylon:~> ruby -v
>> ruby 1.8.6 (2007-03-13 patchlevel 0) [x86_64-linux]
>> hassan@ceylon:~> irb
>> irb(main):001:0> DateTime.now.to_s
>> => "2007-08-20T14:14:31-07:00"
>> irb(main):002:0>
>
> Be careful with irb. It has its own set of startup rules and
> behaviors that
> are slightly different than Ruby itself. Try:
>
> ruby -e 'puts DateTime.now.to_s'
>
> Ruby's startup behaviour can also be changed if the RUBYOPT
> environment
> variable is set.
>
> On my installation irb shows 451 classes defined at startup while
> the Ruby
> interpreter just shows 147 classes.
>
Good call, that's true, irb does require some things automatically.