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Returns true if the provided attribute is being cached.
cache_attributes allows you to declare which converted attribute values should be cached. Usually caching only pays off for attributes with expensive conversion methods, like time related columns (e.g. created_at, updated_at).
Returns the attributes which are cached. By default time related columns with datatype :datetime, :timestamp, :time, :date are cached.
We want to generate the methods via module_eval rather than define_method, because define_method is slower on dispatch and uses more memory (because it creates a closure).
But sometimes the database might return columns with characters that are not allowed in normal method names (like ‘my_column(omg)’. So to work around this we first define with the temp identifier, and then use alias method to rename it to what we want.
# File activerecord/lib/active_record/attribute_methods/read.rb, line 69 69: def define_method_attribute(attr_name) 70: generated_attribute_methods.module_eval "def __temp__\n\#{internal_attribute_access_code(attr_name, attribute_cast_code(attr_name))}\nend\nalias_method '\#{attr_name}', :__temp__\nundef_method :__temp__\n", __FILE__, __LINE__ + 1 71: end