diff options
Diffstat (limited to 'railties/guides/source/active_support_core_extensions.textile')
-rw-r--r-- | railties/guides/source/active_support_core_extensions.textile | 39 |
1 files changed, 6 insertions, 33 deletions
diff --git a/railties/guides/source/active_support_core_extensions.textile b/railties/guides/source/active_support_core_extensions.textile index 9b1d264d2c..dc1200812e 100644 --- a/railties/guides/source/active_support_core_extensions.textile +++ b/railties/guides/source/active_support_core_extensions.textile @@ -167,6 +167,12 @@ def log_info(sql, name, ms) end </ruby> ++try+ can also be called without arguments but a block, which will only be executed if the object is not nil: + +<ruby> +@person.try { |p| "#{p.first_name} #{p.last_name}" } +</ruby> + NOTE: Defined in +active_support/core_ext/object/try.rb+. h4. +singleton_class+ @@ -395,39 +401,6 @@ C.new(0, 1).instance_values # => {"x" => 0, "y" => 1} NOTE: Defined in +active_support/core_ext/object/instance_variables.rb+. -h5. +copy_instance_variables_from(object, exclude = [])+ - -Copies the instance variables of +object+ into +self+. - -Instance variable names in the +exclude+ array are ignored. If +object+ -responds to +protected_instance_variables+ the ones returned are -also ignored. For example, Rails controllers implement that method. - -In both arrays strings and symbols are understood, and they have to include -the at sign. - -<ruby> -class C - def initialize(x, y, z) - @x, @y, @z = x, y, z - end - - def protected_instance_variables - %w(@z) - end -end - -a = C.new(0, 1, 2) -b = C.new(3, 4, 5) - -a.copy_instance_variables_from(b, [:@y]) -# a is now: @x = 3, @y = 1, @z = 2 -</ruby> - -In the example +object+ and +self+ are of the same type, but they don't need to. - -NOTE: Defined in +active_support/core_ext/object/instance_variables.rb+. - h4. Silencing Warnings, Streams, and Exceptions The methods +silence_warnings+ and +enable_warnings+ change the value of +$VERBOSE+ accordingly for the duration of their block, and reset it afterwards: |