class SafetyDance

Generic 'Result' object for declarative result success/failure/cascade handling.

Usage:

def some_action_that_succeeds(msg); msg; end
def some_action_that_fails(msg); raise msg; end

SafetyDance.new { some_action_that_succeeds(:success) } #=> SafetyDance

SafetyDance.new { some_action_that_succeeds(:success) }
  .value {|error| "action failed with error #{error}" } #=> :success

SafetyDance.new { some_action_that_fails("fail")}
  .value {|error| "action failed with error #{error}" } #=> "action failed with error 'RuntimeError fail'"

SafetyDance.new { some_action_that_succeeds(:success) }
  .then { some_action_that_succeeds(:another_success }
  .value {|error| "I am handling #{error}" } # => :another_success

SafetyDance.new { some_action_that_fails("fail1") }
  .then { some_action_that_fails("fail2") }
  .then { some_action_that_succeeds(:another_success }
  .then { some_action_that_fails("fail3") }
  .value {|error| "I am handling #{error}" } # I am handling 'RuntimeError fail1'"

Result object pattern is from johnnunemaker.com/resilience-in-ruby/ e.g. github.com/github/github-ds/blob/fbda5389711edfb4c10b6c6bad19311dfcb1bac1/lib/github/result.rb

Constants

VERSION

Public Class Methods

error(e) click to toggle source

# File lib/safety_dance.rb, line 97
def self.error(e)
  result = allocate
  result.instance_variable_set(:@error, e)
  result
end

new() { || ... } click to toggle source

# File lib/safety_dance.rb, line 31
def initialize
        @value = yield
        @error = nil
rescue => e
        @error = e
end

Public Instance Methods

error() click to toggle source

# File lib/safety_dance.rb, line 52
def error
  @error
end

inspect()

Alias for: to_s

ok?() click to toggle source

# File lib/safety_dance.rb, line 38
def ok?
  @error.nil?
end

rescue() { |error| ... } click to toggle source

# File lib/safety_dance.rb, line 87
def rescue
  return self if ok?
  result = SafetyDance.new { yield(@error) }
  if result.ok? && result.value! == @error
    self
  else
    result
  end
end

then() { |value| ... } click to toggle source

# File lib/safety_dance.rb, line 75
def then
  return self if !ok?
  SafetyDance.new { yield(@value) }
end

then_tap() { |value| ... } click to toggle source

# File lib/safety_dance.rb, line 80
def then_tap
  self.then do |value|
    yield value
    value
  end
end

to_s() click to toggle source

# File lib/safety_dance.rb, line 42
def to_s
  if ok?
    "#<SafetyDance:0x%x value: %s>" % [object_id, @value.inspect]
  else
    "#<SafetyDance:0x%x error: %s>" % [object_id, @error.inspect]
  end
end

Also aliased as: inspect

value() { |error| ... } click to toggle source

# File lib/safety_dance.rb, line 56
def value
  unless block_given?
    fail ArgumentError, "must provide a block to SafetyDance#value to be invoked in case of error"
  end
  if ok?
    @value
  else
    yield @error
  end
end

value!() click to toggle source

# File lib/safety_dance.rb, line 67
def value!
  if ok?
    @value
  else
    raise @error
  end
end