Rails on Ruby: How Ruby Makes Rails Great

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This slide intentionally left self- promotional https://pragprog.com/ titles/ruby5 35% off with code RailsConf_Atlanta

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Let's look at some code

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Rails.env.production? instead of Rails.env == "production"

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It's Rails Magic!

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There's a secret:

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It's all Ruby

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Rails on Ruby: How Ruby Makes Rails Great Noel Rappin (@noelrap@ruby.social) https://www.chime.com http://noelrappin.com

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5 Ruby tricks in the Rails codebase

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We're not going to explain all of Rails' internals

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We're also not going to be defensive about Rails design

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Act 1: String Inquirer

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method_missing the method of last resort

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Allows you to parse the method name

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Rails used to use this for AR record ﬁnders find_all_by_name_and_email

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If the method name ends in ? compare it to the value of the string Rails.env.production?

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respond_to_missing?

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Why do this?

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Flexible to new environments

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Encapsulates knowledge of internals

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Act 2: View Assigns

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Here's some code...

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instance_variables returns a list: ["@user", "@country"]

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returns a hash: {user: "Noel", country: "USA"}

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And some other code

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instance_variable_set("@user", "Noel")

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Easy to use by devs (Especially if you don't think about it)

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Act 3: Callbacks

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define_method

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This is part of the code

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Used by Controllers ActiveJob ActionCable ActiveRecord

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Easy to implement new callback hooks

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Act 4: Dirty

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ActiveRecord::Dirty API > user.zip_code = "60015" > user.zip_code_changed? true > user.zip_code_was "02134"

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included

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Looks for a pattern match

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first_name_was becomes attribute_was(:first_name)

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Also used for ? and =

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AR doesn't like looking up attribute names

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Act 5: Migrations

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class_eval

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Makes reversible migrations very easy

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Conclusion: Why is Rails like this?

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We have to talk about discoverability

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The "Look up Deﬁnition" IDE button doesn't work

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One Neat Trick source_location > ApplicationController.method(:before_action).source_location => ["[REDACTED]/actionpack-7.0.4/lib/abstract_controller/callbacks.rb", 204]

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Flexible

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Generalizable

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Developer experience

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When can you adopt these methods

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This slide intentionally left self-promotional https://pragprog.com/ titles/ruby5 35% off with code RailsConf_Atlanta @noelrap@ruby.social noelrappin.com