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Diffstat (limited to 'railties/guides/source/active_support_core_extensions.textile')
| -rw-r--r-- | railties/guides/source/active_support_core_extensions.textile | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/railties/guides/source/active_support_core_extensions.textile b/railties/guides/source/active_support_core_extensions.textile index 8ba283122d..0e4f1da7b2 100644 --- a/railties/guides/source/active_support_core_extensions.textile +++ b/railties/guides/source/active_support_core_extensions.textile @@ -48,6 +48,14 @@ The method +present?+ is equivalent to +!blank?+: assert @response.body.present? # same as !@response.body.blank? </ruby> +h4. +presence+ + +The +presence+ method returns its receiver if +present?+, and +nil+ otherwise. It is useful for idioms like this: + +<ruby> +host = config[:host].presence || 'localhost' +</ruby> + h4. +duplicable?+ A few fundamental objects in Ruby are singletons. For example, in the whole live of a program the integer 1 refers always to the same instance: |