Everybody thanks for the explanation.
I have another problem.
On this :
def test_accessing_hashes_with_fetch
hash = { :one => "uno" }
assert_equal "uno", hash.fetch(:one)
assert_raise("Class: <IndexError> Message: <"key not found">
---Backtrace--- ./about_hashes.rb:27:in `fetch' ./about_hashes.rb:27:in
`test_accessing_hashes_with_fetch' ") do
hash.fetch(:doesnt_exist)
end
I get always a syntax error.
How to solve this one?
Roelof
Op woensdag 19 september 2012 05:29:59 UTC+2 schreef cming xu het volgende:
>
> As far as i know, ruby use memory location to generate object's id,
> normally any dynamic objects(runtime generate objects) will have different
> object_id, for example "foo".object_id not equal with "foo".object_id. But,
> any object like number, true, false ,nil and symbol all have fixed object_id
>
> --
> rubyonrailsx
> Sent with Sparrow <http://www.sparrowmailapp.com/?sig>
>
> On Wednesday, September 19, 2012 at 1:23 AM, roelof wrote:
>
> Hello,
>
> Im trying to learn ruby by using koans.
>
> Now I have to fill in this part.
>
> def test_some_system_objects_always_have_the_same_id
> assert_equal --, false.object_id
> assert_equal --, true.object_id
> assert_equal --, nil.object_id
> end
>
> According to the answers I have to fill in like this :
>
> def test_some_system_objects_always_have_the_same_id
> assert_equal 0, false.object_id
> assert_equal 2, true.object_id
> assert_equal 4, nil.object_id
> end
>
> But how can I normally know the id of a object ?
>
> Roelof
>
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