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45 lines
1.7 KiB
Markdown
45 lines
1.7 KiB
Markdown
# Make Structs Easier To Use With Keyword Initialization
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Typically a [`Struct`](https://ruby-doc.org/3.4.1/Struct.html#method-c-new) in
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Ruby is defined and initialized like so:
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```ruby
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> Subscriber = Struct.new(:email, :first_name, :status, :tags)
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=> Subscriber
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> s1 = Subscriber.new('bob.burgers@example.com', 'Bob', :active, [:food, :family])
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=> #<struct Subscriber email="bob.burgers@example.com", first_name="Bob", status=:active, tags=[:food, :family]>
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> s1.email
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=> "bob.burgers@example.com"
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```
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That's a nice way to structure light-weight objects.
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A potential challenge with multi-argument `Struct` definitions like this,
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especially when they aren't colocated with initialization, is that it can be
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hard to remember or distinguish the argument order when initializing an instance
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of one.
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Ruby 2.5 added the `keyword_init` option to help with this exact issue. When
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that option is set to `true` for a `Struct` definition, then we get to
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initialize it with keyword arguments rather than positional arguments.
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```ruby
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> Subscriber = Struct.new(:email, :first_name, :status, :tags, keyword_init: true)
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=> Subscriber(keyword_init: true)
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* s1 = Subscriber.new(
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* first_name: 'Bob',
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* email: 'bob.burgers@example.com',
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* tags: [:food, :family],
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* status: :active
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> )
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=> #<struct Subscriber email="bob.burgers@example.com", first_name="Bob", status=:active, tags=[:food, :family]>
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> s1.email
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=> "bob.burgers@example.com"
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```
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Notice I have to use keyword arguments now and that because of that I can
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organize them in whatever order makes sense. Coming back to view this line of
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code later, it is easy to see attribute each value corresponds to.
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[source](https://www.bigbinary.com/blog/ruby-2-5-allows-creating-structs-with-keyword-arguments)
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