Add Specify Default For Data Definition as a Ruby TIL

ruby/specify-default-for-data-definition.md

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+# Specify Default For Data Definition
+
+Here is what a `Data` definition for the concept of a `Permission` might look
+like:
+
+```ruby
+Permission = Data.define(:id, :name, :description, :enabled)
+
+perm1 = Permission.new(
+  id: 123,
+  name: :can_edit,
+  description: "User is allowed to edit.",
+  enabled: true
+)
+```
+
+However, as we're creating various `Permission` entities, we may find that the
+vast majority of them are _enabled_ by default and so we'd like to apply `true`
+as a default value.
+
+We cannot do this directly in the `Data` definition, but we can open a block to
+override the `initialize` method.
+
+```ruby
+Permission = Data.define(:id, :name, :description, :enabled) do
+  def initialize(:id, :name, :description, enabled: true)
+    super
+  end
+end
+
+perm1 = Permission.new(
+  id: 123,
+  name: :can_edit,
+  description: "User is allowed to edit."
+)
+
+perm1.enabled #=> true
+```
+
+Now we're able to create a `Permission` without specifying the `enabled`
+attribute and it takes on the default of `true`.
+
+[source](https://dev.to/baweaver/new-in-ruby-32-datadefine-2819#comment-254o8)