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Diffstat (limited to 'guides/source/active_support_core_extensions.md')
| -rw-r--r-- | guides/source/active_support_core_extensions.md | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/guides/source/active_support_core_extensions.md b/guides/source/active_support_core_extensions.md index e34af8aa8d..23f53ac084 100644 --- a/guides/source/active_support_core_extensions.md +++ b/guides/source/active_support_core_extensions.md @@ -755,6 +755,8 @@ NOTE: Defined in `active_support/core_ext/module/anonymous.rb`. ### Method Delegation +#### `delegate` + The macro `delegate` offers an easy way to forward methods. Let's imagine that users in some application have login information in the `User` model but name and other data in a separate `Profile` model: @@ -837,13 +839,32 @@ In the previous example the macro generates `avatar_size` rather than `size`. NOTE: Defined in `active_support/core_ext/module/delegation.rb` +#### `delegate_missing_to` + +Imagine you would like to delegate everything missing from the `User` object, +to the `Profile` one. The `delegate_missing_to` macro lets you implement this +in a breeze: + +```ruby +class User < ApplicationRecord + has_one :profile + + delegate_missing_to :profile +end +``` + +The target can be anything callable within the object, e.g. instance variables, +methods, constants, etc. Only the public methods of the target are delegated. + +NOTE: Defined in `active_support/core_ext/module/delegation.rb`. + ### Redefining Methods There are cases where you need to define a method with `define_method`, but don't know whether a method with that name already exists. If it does, a warning is issued if they are enabled. No big deal, but not clean either. The method `redefine_method` prevents such a potential warning, removing the existing method before if needed. -NOTE: Defined in `active_support/core_ext/module/remove_method.rb` +NOTE: Defined in `active_support/core_ext/module/remove_method.rb`. Extensions to `Class` --------------------- @@ -931,7 +952,7 @@ When `:instance_reader` is `false`, the instance predicate returns a `NoMethodEr If you do not want the instance predicate, pass `instance_predicate: false` and it will not be defined. -NOTE: Defined in `active_support/core_ext/class/attribute.rb` +NOTE: Defined in `active_support/core_ext/class/attribute.rb`. #### `cattr_reader`, `cattr_writer`, and `cattr_accessor` @@ -1827,7 +1848,7 @@ as well as adding or subtracting their results from a Time object. For example: (4.months + 5.years).from_now ``` -NOTE: Defined in `active_support/core_ext/numeric/time.rb` +NOTE: Defined in `active_support/core_ext/numeric/time.rb`. ### Formatting |