# ![Surrounded](http://saturnflyer.github.io/surrounded/images/surrounded.png "Surrounded") ## Be in control of business logic. [![Build Status](https://travis-ci.org/saturnflyer/surrounded.png?branch=master)](https://travis-ci.org/saturnflyer/surrounded) [![Code Climate](https://codeclimate.com/github/saturnflyer/surrounded.png)](https://codeclimate.com/github/saturnflyer/surrounded) Surrounded is designed to help you better manage your business logic by keeping cohesive behaviors together. Bring objects together to implement your use cases and gain behavior only when necessary. ## How to think about your objects First, name the problem you're solving. Then, break down your problem into responsible roles. Use your problem name as a class and extend it with `Surrounded::Context` It might look like this: ```ruby class Employment extend Surrounded::Context role :boss role :employee end ``` In your application, you'll initialize this class with objects to play the roles that you've defined, so you'll need to specify which role players will use which role. ```ruby class Employment extend Surrounded::Context initialize :employee, :boss role :boss role :employee end ``` Here, you've specified the order when initializing so you can use it like this: ```ruby user1 = User.find(1) user2 = User.find(2) context = Employment.new(employee: user1, boss: user2) ``` That ensures that `user1` will become (and have all the features of) the `employee` and `user2` will become (and have all the features of) the `boss`. There are 2 things left to do: 1. define behaviors for each role and 2. define how you can trigger their actions Initializing contexts does not require the use of keyword arguments, but you may opt out. You should consider using explicit names when initialize now by using `initialize_without_keywords`: ```ruby class Employment extend Surrounded::Context initialize_withou_keywords :employee, :boss end user1 = User.find(1) user2 = User.find(2) context = Employment.new(user1, user2) ``` This will allow you to prepare your accessing code to use keywords. If you need to override the initializer with additional work, you have the ability to use a block to be evaluated in the context of the initialized object. ```ruby initialize :role1, :role2 do map_role(:role3, 'SomeRoleConstantName', initialize_the_object_to_play) end ``` This block will be called _after_ the default initialization is done. ## Defining behaviors for roles Behaviors for your roles are easily defined just like you define a method. Provide your role a block and define methods there. ```ruby class Employment extend Surrounded::Context initialize :employee, :boss role :boss role :employee do def work_weekend if fed_up? quit else schedule_weekend_work end end def quit say("I'm sick of this place, #{boss.name}!") stomp throw_papers say("I quit!") end def schedule_weekend_work # ... end end end ``` If any of your roles don't have special behaviors, like `boss`, you don't need to specify it. Your `initialize` setup will handle assiging who's who when this context is used. ```ruby class Employment extend Surrounded::Context initialize :employee, :boss role :employee do #... end end ``` ## Triggering interactions You'll need to define way to trigger these behaviors to occur so that you can use them. ```ruby context = Employment.new(employee: user1, boss: user2) context.plan_weekend_work ``` The method you need is defined as an instance method in your context, but before that method will work as expected you'll need to mark it as a trigger. ```ruby class Employment extend Surrounded::Context initialize :employee, :boss def plan_weekend_work employee.work_weekend end trigger :plan_weekend_work role :employee do #... end end ``` Trigger methods are different from regular instance methods in that they apply behaviors from the roles to the role players. A regular instance method just does what you define. But a trigger will make your role players come alive with their behaviors. You may find that the code for your triggers is extremely simple and is merely creating a method to tell a role player what to do. If you find you have many methods like this: ```ruby def plan_weekend_work employee.work_weekend end trigger :plan_weekend_work ``` You can shorten it to: ```ruby trigger :plan_weekend_work do employee.work_weekend end ``` But it can be even simpler and follows the same pattern provided by Ruby's standard library Forwardable: ```ruby # The first argument is the role to receive the messaged defined in the second argument. # The third argument is optional and if provided will be the name of the trigger method on your context instance. forward_trigger :employee, :work_weekend, :plan_weekend_work # Alternatively, you can use an API similar to that of the `delegate` method from Forwardable forwarding [:work_weekend] => :employee ``` The difference between `forward_trigger` and `forwarding` is that the first accepts an alternative method name for the context instance method. There's more on this below in the "Overview in code" section, or see `lib/surrounded/context/forwarding.rb`. There's one last thing to make this work. ## Getting your role players ready You'll need to include `Surrounded` in the classes of objects which will be role players in your context. It's as easy as: ```ruby class User include Surrounded # ... end ``` This gives each of the objects the ability to understand its context and direct access to other objects in the context. ## Why is this valuable? By creating environments which encapsulate roles and all necessary behaviors, you will be better able to isolate the logic of your system. A `user` in your system doesn't have all possible behaviors defined in its class, it gains the behaviors only when they are necessary. The objects that interact have their behaviors defined and available right where they are needed. Implementation is in proximity to necessity. The behaviors you need for each role player are highly cohesive and are coupled to their use rather than being coupled to the class of an object which might use them at some point. # Deeper Dive ## Create encapsulated environments for your objects. Typical initialization of an environment, or a Context in DCI, has a lot of code. For example: ```ruby class Employment attr_reader :employee, :boss private :employee, :boss def initialize(employee, boss) @employee = employee.extend(Employee) @boss = boss end module Employee # extra behavior here... end end ``` This code allows the Employment class to create instances where it will have an `employee` and a `boss` role internally. These are set to `attr_reader`s and are made private. The `employee` is extended with behaviors defined in the `Employee` module, and in this case there's no extra stuff for the `boss` so it doesn't get extended with anything. Most of the time you'll follow a pattern like this. Some objects will get extra behavior and some won't. The modules that you use to provide the behavior will match the names you use for the roles to which you assign objects. By adding `Surrounded::Context` you can shortcut all this work. ```ruby class Employment extend Surrounded::Context initialize(:employee, :boss) module Employee # extra behavior here... end end ``` Surrounded gives you an `initialize` class method which does all the setup work for you. ## Managing Roles _I don't want to use modules. Can't I use something like SimpleDelegator?_ Well, it just so happens that you can. This code will work just fine: ```ruby class Employment extend Surrounded::Context initialize(:employee, :boss) class Employee < SimpleDelegator # extra behavior here... end end ``` Instead of extending the `employee` object, Surrounded will run `Employee.new(employee)` to create the wrapper for you. You'll need to include the `Surrounded` module in your wrapper, but we'll get to that. But the syntax can be even simpler than that if you want. ```ruby class Employment extend Surrounded::Context initialize(:employee, :boss) role :employee do # extra behavior here... end end ``` By default, this code will create a module for you named `Employee`. If you want to use a wrapper, you can do this: ```ruby class Employment extend Surrounded::Context initialize(:employee, :boss) wrap :employee do # extra behavior here... end end ``` But if you're making changes and you decide to move from a module to a wrapper or from a wrapper to a module, you'll need to change that method call. Instead, you could just tell it which type of role to use: ```ruby class Employment extend Surrounded::Context initialize(:employee, :boss) role :employee, :wrapper do # extra behavior here... end end ``` The default available types are `:module`, `:wrap` or `:wrapper`, and `:interface`. We'll get to `interface` below. The `:wrap` and `:wrapper` types are the same and they'll both create classes which inherit from SimpleDelegator _and_ include Surrounded for you. These are minor little changes which highlight how simple it is to use Surrounded. _Well... I want to use [Casting](https://github.com/saturnflyer/casting) so I get the benefit of modules without extending objects. Can I do that?_ Yup. The ability to use Casting is built-in. If the objects you provide to your context respond to `cast_as` then Surrounded will use that. _Ok. So is that it?_ There's a lot more. Let's look at the individual objects and what they need for this to be valuable... ## Objects' access to their environments Add `Surrounded` to your objects to give them awareness of other objects. ```ruby class User include Surrounded end ``` Now the `User` instances will be able to implicitly access objects in their environment. Via `method_missing` those `User` instances can access a `context` object it stores in an internal collection. Inside of the `Employment` context we saw above, the `employee` and `boss` objects are instances of `User` for this example. Because the `User` class includes `Surrounded`, the instances of that class will be able to access other objects in the same context implicitly. Let's make our context look like this: ```ruby class Employment # other stuff from above is still here... def plan_weekend_work employee.quit end role :employee do def quit say("I'm sick of this place, #{boss.name}!") stomp throw_papers say("I quit!") end end end ``` What's happening in there is that when the `plan_weekend_work` method is called on the instance of `Employment`, the `employee` has the ability to refer to `boss` because it is in the same context, e.g. the same environment. The behavior defined in the `Employee` module assumes that it may access other objects in it's local environment. The `boss` object, for example, is never explicitly passed in as an argument. What `Surrounded` does for us is to make the relationship between objects and gives them the ability to access each other. Adding new or different roles to the context now only requires that we add them to the context and nothing else. No explicit references must be passed to each individual method. The objects are aware of the other objects around them and can refer to them by their role name. I didn't mention how the context is set, however. ## Tying objects together Your context will have methods of it's own which will trigger actions on the objects inside, but we need those trigger methods to set the accessible context for each of the contained objects. Here's an example of what we want: ```ruby class Employment # other stuff from above is still here... def plan_weekend_work employee.store_context(self) employee.quit employee.remove_context end role :employee do def quit say("I'm sick of this place, #{boss.name}!") stomp throw_papers say("I quit!") end end end ``` Now that the `employee` has a reference to the context, it won't blow up when it hits `boss` inside that `quit` method. We saw how we were able to clear up a lot of that repetitive work with the `initialize` method, so this is how we do it here: ```ruby class Employment # other stuff from above is still here... trigger :plan_weekend_work do employee.quit end role :employee do def quit say("I'm sick of this place, #{boss.name}!") stomp throw_papers say("I quit!") end end end ``` By using this `trigger` keyword, our block is the code we care about, but internally the method is created to first set all the objects' current contexts. The context will also store the triggers so that you can, for example, provide details outside of the environment about what triggers exist. ```ruby context = Employment.new(current_user, the_boss) context.triggers #=> [:plan_weekend_work] ``` You might find that useful for dynamically defining user interfaces. Sometimes I'd rather not use this DSL, however. I want to just write regular methods. We can do that too. You'll need to opt in to this by specifying `trigger :your_method_name` for the methods you want to use. ```ruby class Employment # other stuff from above is still here... def plan_weekend_work employee.quit end trigger :plan_weekend_work # or in Ruby 2.x trigger def plan_weekend_work employee.quit end role :employee do def quit say("I'm sick of this place, #{boss.name}!") stomp throw_papers say("I quit!") end end end ``` This will allow you to write methods like you normally would. They are aliased internally with a prefix and the method name that you use is rewritten to add and remove the context for the objects in this context. The public API of your class remains the same, but the extra feature of wrapping your method is handled for you. This works like Ruby's `public`,`protected`, and `private` keywords in that you can send symbols of method names to it. But `trigger` does not alter the parsing of the document like those core keywords do. In other words, you can't merely type `trigger` on one line, and have methods added afterward be treated as trigger methods. ## Access Control / Permissions for Triggers If you decide to build a user interface from the available triggers, you'll find you need to know what triggers are available. Fortunately, you can make it easy. By running `protect_triggers` you'll be able to define when triggers may or may not be run. You can still run them, but they'll raise an error. Here's an example. ```ruby class Employment extend Surrounded::Context protect_triggers def plan_weekend_work employee.quit end trigger :plan_weekend_work disallow :plan_weekend_work do employee.bank_balance > 1000000 end end ``` Then, when the employee role's `bank_balance` is greater than `1000000`, the available triggers won't include `:plan_weekend_work`. You can compare the instance of the context by listing `all_triggers` and `triggers` to see what could be possible and what's currently possible. Alternatively, if you just want to define your own methods without the DSL using `disallow`, you can just follow the pattern of `disallow_#{method_name}?` when creating your own protection. In fact, that's exactly what happens with the `disallow` keyword. After using it here, we'd have a `disallow_plan_weekend_work?` method defined. If you call the disallowed trigger directly, you'll raise an `Employment::AccessError` exception and the code in your trigger will not be run. You may rescue from that or you may rescue from `Surrounded::Context::AccessError` although you should prefer to use the error name from your own class. ## Restricting return values _Tell, Don't Ask_ style programming can better be enforced by following East-oriented Code principles. This means that the return values from methods on your objects should not provide information about their internal state. Instead of returning values, you can enforce that triggers return the context object. This forces you to place context responsiblities inside the context and prevents leaking the details and responsiblities outside of the system. Here's how you enforce it: ```ruby class Employment extend Surrounded::Context east_oriented_triggers end ``` That's it. With that change, any trigger you define will execute the block you provide and return `self`, being the instance of the context. ## Where roles exist By using `Surrounded::Context` you are declaring a relationship between the objects inside playing your defined roles. Because all the behavior is defined internally and only relevant internally, those relationships don't exist outside of the environment. Surrounded makes all of your role modules and classes private constants. It's not a good idea to try to reuse behavior defined for one context in another area. ## The role DSL Using the `role` method to define modules and classes takes care of the setup for you. This way you can swap between implementations: ```ruby # this uses modules which include Surrounded role :source do def transfer self.balance -= amount destination.balance += amount self end end # this uses SimpleDelegator and Surrounded role :source, :wrap do def transfer self.balance -= amount destination.balance += amount __getobj__ end end # this uses a special interface object which pulls # methods from a module and applies them to your object. role :source, :interface do def transfer self.balance -= amount # not able to access destination unless the object playing source is Surrounded destination.balance += amount self end end ``` The `:interface` option is a special object which has all of the standard Object methods removed (excepting ones like `__send__` and `object_id`) so that other methods will be pulled from the ones that you define, or from the object it attempts to proxy. Notice that the `:interface` allows you to return `self` whereas the `:wrap` acts more like a wrapper and forces you to deal with that shortcoming by using it's wrapped-object-accessor method: `__getobj__`. The downside of using an interface is that it is still a wrapper and it only has access to the other objects in the context if the wrapped object already includes Surrounded. All of your defined role methods are executed in the context of the object playing the role, but the interface has it's own identity. If you'd like to choose one and use it all the time, you can set the default: ```ruby class MoneyTransfer extend Surrounded::Context self.default_role_type = :interface # also :wrap, :wrapper, or :module role :source do def transfer self.balance -= amount destination.balance += amount self end end end ``` Or, if you like, you can choose the default for your entire project: ```ruby Surrounded::Context.default_role_type = :interface class MoneyTransfer extend Surrounded::Context role :source do def transfer self.balance -= amount destination.balance += amount self end end end ``` ## Working with collections If you want to use an Array of objects (for example) as a role player in your context, you may do so. If you want each item in your collection to gain behavior, you merely need to create a role for the items. Surrounded will attempt to guess at the singular role name. For example, a role player named `members` would be given the behaviors from a `Members` behavior module or class. Each item in your `members` collection would be given behavior from a `Member` behavior module or class if you create one. ```ruby class Organization extend Surrounded::Context initialize_without_keywords :leader, :members role :members do # special behavior for the collection end role :member do # special behavior to be applied to each member in the collection end end ``` ## Reusing context objects If you create a context object and need to use the same type of object with new role players, you may use the `rebind` method. It will clear any instance_variables from your context object and map the given objects to their names: ```ruby context = Employment.new(employee: current_user, boss: the_boss) context.rebind(employee: another_user, boss: someone_else) # same context, new players ``` ## Background Processing While there's no specific support for background processing, your context objects make it easy for you to add your own by remembering what arguments were provided during initialization. When you initialize a context, it will keep track of the parameters and their matching arguments in a private hash called `initializer_arguments`. This allows you to write methods to create a context object and have itself sent to a background processor. ```ruby class ExpensiveCalculation extend Surrounded::Context initialize :leader, :members def send_to_background(trigger_method) background_arguments = initializer_arguments.merge(trigger: trigger_method) BackgroundProcessor.enqueue(self.class.name, **background_arguments) end class BackgroundProcessor def perform(**args) trigger_name = args.delete(:trigger) job_class.new(args).send(trigger_name) end end end ExpensiveCalculation.new(leader: some_object, members: some_collection).send_to_background(:do_expensive_calculation) ``` The above example is merely pseudo-code to show how `initializer_arguments` can be used. Customize it according to your own needs. ## Overview in code Here's a view of the possibilities in code. ```ruby # set default role type for *all* contexts in your program Surrounded::Context.default_role_type = :module # also :wrap, :wrapper, or :interface class ActiviatingAccount extend Surrounded::Context # set the default role type only for this class self.default_role_type = :module # also :wrap, :wrapper, or :interface # shortcut initialization code initialize(:activator, :account) # or handle it yourself def initialize(activator:, account:) # this must be done to handle the mapping of roles to objects # pass an array of arrays with role name symbol and the object for that role map_roles([[:activator, activator],[:account, account]]) # or pass a hash map_roles(:activator => activator, :account => account) # or load extra objects, perform other functions, etc. if you need and then use super account.perform_some_funtion super end # these also must be done if you create your own initialize method. # this is a shortcut for using attr_reader and private private_attr_reader :activator, :account # If you need to mix default initialzation and extra work use a block initialize :activator, :account do map_roles(:third_party => get_some_other_object) # explicitly set a single role map_role(:something_new, 'SomeRoleConstant', object_to_play_the_role) end # but remember to set the extra accessors: private_attr_reader :third_party, :something_new # initialize without keyword arguments initialize_without_keywords(:activator, :account) # this makes the following instance method signature with positional arguments def initialize(activator, account) # ... end # Handle method name collisions on role players against role names in the context on_name_collision :raise # will raise your context namespaced error: ActiviatingAccount::NameCollisionError on_name_collision :warn on_name_collision ->(message){ puts "Here's the message! #{message}" } on_name_collision :my_custom_handler def my_custom_handler(message) # do something with the message here end role :activator do # module by default def some_behavior; end end # role_methods :activator, :module do # alternatively use role_methods if you choose # def some_behavior; end # end # # role :activator, :wrap do # def some_behavior; end # end # # role :activator, :interface do # def some_behavior; end # end # # use your own classes if you don't want SimpleDelegator # class SomeSpecialRole # include Surrounded # <-- you must remember this in your own classes # # Surrounded assumes SomeSpecialRole.new(some_special_role) # def initialize(...); # # ... your code here # end # end # if you use a regular method and want to use context-specific behavior, # you must handle storing the context yourself: def regular_method apply_behaviors # handles the adding of all the roles and behaviors activator.some_behavior # behavior not available unless you apply roles on initialize ensure # Use ensure to enforce the removal of behaviors in case of exceptions. # This also does not affect the return value of this method. remove_behaviors # handles the removal of all roles and behaviors end # This trigger or the forward* methods are preferred for creating triggers. trigger :some_trigger_method do activator.some_behavior # behavior always available end trigger def some_other_trigger activator.some_behavior # behavior always available end def regular_non_trigger activator.some_behavior # behavior always available with the following line end trigger :regular_non_trigger # turns the method into a trigger # create restrictions on what triggers may be used protect_triggers # <-- this is required if you want to protect your triggers this way. disallow :some_trigger_method do # whatever conditional code for the instance of the context end # you could also use `guard` instead of `disallow` # or define your own method without the `disallow` keyword def disallow_some_trigger_method? # whatever conditional code for the instance of the context end # Prefer using `disallow` because it will wrap role players in their roles for you; # the `disallow_some_trigger_method?` defined above, does not. # Create shortcuts for triggers as class methods # so you can do ActiviatingAccount.some_trigger_method(activator, account) # This will make all triggers shortcuts. shortcut_triggers # Alterantively, you could implement shortcuts individually: def self.some_trigger_method(activator, account) instance = self.new(activator, account) instance.some_trigger_method end # Set triggers to always return the context object # so you can enforce East-oriented style or Tell, Don't Ask east_oriented_triggers # Forward context instance methods as triggers to role players forward_trigger :role_name, :method_name forward_trigger :role_name, :method_name, :alternative_trigger_name_for_method_name forward_triggers :role_name, :list, :of, :methods, :to, :forward forwarding [:list, :of, :methods, :to, :forward] => :role_name end # with initialize (also keyword_initialize) context = ActiviatingAccount.new(activator: some_object, account: some_account) # with initialize_without_keywords context = ActiviatingAccount.new(some_object, some_account) context.triggers # => lists a Set of triggers # when using protect_triggers context.triggers # => lists a Set of triggers which may currently be called context.triggers # => lists a Set of all triggers (the same as if protect_triggers was _not_ used) context.allow?(:trigger_name) # => returns a boolean if the trigger may be run # reuse the context object with new role players context.rebind(activator: another_object, account: another_account) ``` ## Dependencies The dependencies are minimal. The plan is to keep it that way but allow you to configure things as you need. The [Triad](http://github.com/saturnflyer/triad) project was written specifically to manage the mapping of roles and objects to the modules which contain the behaviors. It is used in Surrounded to keep track of role player, roles, and role constant names but it is not a hard requirement. You may implement your own but presently you'll need to dive into the implementation to fully understand how. Future updates may provide better support and guidance. If you're using [Casting](http://github.com/saturnflyer/casting), for example, Surrounded will attempt to use that before extending an object, but it will still work without it. ## Support for other ways to apply behavior Surrounded is designed to be flexible for you. If you have your own code to manage applying behaviors, you can setup your context class to use it. ### Additional libraries Here's an example using [Behavioral](https://github.com/saturnflyer/behavioral) ```ruby class MyCustomContext extend Surrounded::Context initialize :employee, :boss def module_extension_methods [:with_behaviors].concat(super) end def module_removal_methods [:without_behaviors].concat(super) end end ``` If you're using your own non-SimpleDelegator wrapper you can conform to that; whatever it may be. ```ruby class MyCustomContext extend Surrounded::Context initialize :employee, :boss class Employee < SuperWrapper include Surrounded # defined behaviors here... def wrapped_object # return the object that is wrapped end end def unwrap_methods [:wrapped_object] end end ``` ### Applying individual roles If you'd like to use a special approach for just a single role, you may do that too. When applying behaviors from a role to your role players, your Surrounded context will first look for a method named `"apply_behavior_#{role}"`. Define your own method and set it to accept 2 arguments: the role constant and the role player. ```ruby class MyCustomContext extend Surrounded::Context initialize :employee, :boss def apply_behavior_employee(behavior_constant, role_player) behavior_constant.build(role_player).apply # or whatever your need to do with your constant and object. end end ``` You can also plan for special ways to remove behavior as well. ```ruby class MyCustomContext extend Surrounded::Context initialize :employee, :boss def remove_behavior_employee(behavior_constant, role_player) role_player.cleanup # or whatever your need to do with your constant and object. end end ``` You can remember the method name by the convention that `remove` or `apply` describes it's function, `behavior` refers to the first argument (thet contsant holding the behaviors), and then the name of the role which refers to the role playing object: `remove_behavior_role`. ##Name collisions between methods and roles Lets say that you wish to create a context as below, intending to use instances of the following two classes as role players: ```ruby class Postcode # other methods... def code @code end def country @country end end class Country # other methods... def country_code @code end end class SendAParcel extend Surrounded::Context keyword_initialize :postcode, :country trigger :send do postcode.send end end role :postcode do def send # do things... country_code = country.country_code # name collision...probably raises an exception! end end end ``` When you call the `:send` trigger you are likely to be greeted with an `NoMethodError` exception. The reason for this is that there is a name collision between `Postcode#country`, and the `:country` role in the `SendAParcel` context. Where a name collision exists, the method in the role player overrides that of the calling class and you get unexpected results. To address this issue, use `on_name_collision` to specify the name of a method to use when collisions are found: ```ruby class SendAParcel extend Surrounded::Context on_name_collision :raise end ``` This option will raise an exception (obviously). You may use any method which is available to the context but it must accept a single message as the argument. You can also use a lambda: ```ruby class SendAParcel extend Surrounded::Context on_name_collision ->(message){ puts "Here's the message: #{message}"} end ``` You may also user a class method: ```ruby class SendAParcel extend Surrounded::Context def self.handle_collisions(message) Logger.debug "#{Time.now}: #{message}" end end ``` ## How to read this code If you use this library, it's important to understand it. As much as possible, when you use the Surrounded DSL for creating triggers, roles, initialize methods, and others you'll likely find the actual method definitions created in a module and then find that module included in your class. This is a design choice which allows you to override any standard behavior more easily. ### Where methods exist and why When you define an initialize method for a Context class, Surrounded _could_ define the method on your class like this: ```ruby def initialize(*roles) self.class_eval do # <=== this evaluates on _your_ class and defines it there. # code... end end ``` If we used the above approach, you'd need to redefine initialize in its entirety: ```ruby initialize(:role1, role2) def initialize(role1, role2) # <=== this will completely redefine initialize on _this class_ super # <=== this will NOT be the initialize method as provided to the Surrounded initialize above. end ``` Surrounded uses a more flexible approach for you: ```ruby def initialize(*roles) mod = Module.new mod.class_eval do # <=== this evaluates on the module and defines it there. # code... end include mod # <=== this adds it to the class ancestors end ``` With this approach you can use the way Surrounded is setup, but make changes if you need. ```ruby initialize(:role1, :role2) # <=== defined in a module in the class ancestors def initialize(role1, role2) super # <=== run the method as defined above in the Surrounded DSL # ... then do additional work end ``` ### Read methods, expect modules When you go to read the code, expect to find behavior defined in modules. ## Installation Add this line to your application's Gemfile: ```ruby gem 'surrounded' ``` And then execute: $ bundle Or install it yourself as: $ gem install surrounded ## Installation for Rails See [surrounded-rails](https://github.com/saturnflyer/surrounded-rails) ## Contributing 1. Fork it 2. Create your feature branch (`git checkout -b my-new-feature`) 3. Commit your changes (`git commit -am 'Add some feature'`) 4. Push to the branch (`git push origin my-new-feature`) 5. Create new Pull Request