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| -rw-r--r-- | railties/guides/source/active_support_overview.textile | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/railties/guides/source/active_support_overview.textile b/railties/guides/source/active_support_overview.textile index ab9390883b..a88432dc3b 100644 --- a/railties/guides/source/active_support_overview.textile +++ b/railties/guides/source/active_support_overview.textile @@ -78,6 +78,23 @@ class Proc end </ruby> +h4. +acts_like?(duck)+ + +The method +acts_like+ provides a way to check whether some class acts like some other class based on a simple convention: a class that provides the same interface as +String+ defines + +<ruby> +def acts_like_string? +end +</ruby> + +which is only a marker, its body or return value are irrelevant. Then, client code can query for duck-type-safeness this way: + +<ruby> +some_klass.acts_like?(:string) +</ruby> + +Rails has classes that act like +Date+ or +Time+ and follow this contract. + h3. Extensions to +Module+ ... |