Adds Interactor path transition switch

[ahmad-elassuty]

Introducing Switcher: a new type of Interactors. Switcher aims to provide a path transition switch mechanism. Each path can be an Interactor or an Organizer that defines multiple scenarios of application's business logic.

Flow

For example, consider the following diagram:

The S class in the previous diagram can be defined as:

class S
  include Interactor::Switcher

  # Switch
  # First path: [B, E]
  # Second path: C

  switch [B, E], C
end

Switcher's behaviour is controlled by switcher_condition attribute that can be provided through the library's regular context object. Hence, if context.switcher_condition equals 1, then the second path, that includes C, will be executed.

.switch class Method

The switch class method accepts arguments in one of the following flavours:

• List of Interactor class arguments:

  #1st path: A
  #2nd path: B
  #3rd path: C
  
  switch A, B, C

  • Where each argument is considered as a separate path.
  • A path can be selected by its index.

• An array of arguments:

  #path: A, B, C
  
  switch [A, B, C]

  • Defines a single path.
  • A path can be selected by its index.

• A hash of arguments:

  #1st path: A, B
  #2nd path: C
  
  switch key_1: [A, B], key_2: C

  • Where each key refers to a separate path.
  • A path can be selected by its key.

    General Note:

• A path is an Array input.
• If switcher_condition is not available, the switcher executes the first path by default.

  TODO

• Fix comments and tests' description typos.
• Add the ability to change the control argument name per switcher. switcher_condition
• Add documentations.

[laserlemon]

Closing because:

1. The API isn't very clear or obvious.
2. I'd like to avoid any reserved words in the context.