Class: LifecycleVM::OpBase

Inherits:
Object
  • Object
show all
Defined in:
lib/lifecycle_vm/op_base.rb

Overview

Base class for all ops in a vm. An op may read and write to vm memory by declaring reads and writes using the DSL. The lifecycle of an op is initialize -> call -> validate, and all three methods will always be called. All reads and logger will be provided before initialize is called.

An op may indicate that it encountered an error or otherwise failed by calling #error. If an op has any errors, no writes will be persisted to the vm memory.

Defined Under Namespace

Classes: InvalidAttr

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#errors ⇒ Object (readonly)

Returns the value of attribute errors.



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# File 'lib/lifecycle_vm/op_base.rb', line 118

def errors
  @errors
end

#logger ⇒ Object (readonly)

Returns the value of attribute logger.



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# File 'lib/lifecycle_vm/op_base.rb', line 118

def logger
  @logger
end

Class Method Details

.call(memory) ⇒ Object

Execute the current op with the gien vm memory. This will read out all declared reads from memory and if executed without any errors will write all declared writes to memory.



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# File 'lib/lifecycle_vm/op_base.rb', line 83

def self.call(memory)
  obj = allocate

  @reads ||= {}
  @writes ||= {}

  @reads.each do |(attribute, ivar)|
    raise InvalidAttr.new(self, attribute) unless memory.respond_to?(attribute)

    obj.instance_variable_set(ivar, memory.send(attribute).clone)
  end

  @writes.each do |(attribute, setter)|
    raise InvalidAttr.new(self, attribute) unless memory.respond_to?(setter)
  end

  obj.instance_variable_set(:"@logger", memory.logger)
  obj.instance_variable_set(:"@errors", nil)

  obj.send(:initialize)
  obj.send(:call)
  obj.send(:validate)

  unless obj.errors?
    @writes.each do |(attribute, setter)|
      memory.send(setter, obj.send(attribute))
    end
  end

  obj
end

.reads(*attrs) ⇒ Object

Read one or more values out of vm memory and provide them as readable attributes



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# File 'lib/lifecycle_vm/op_base.rb', line 43

def self.reads(*attrs)
  @reads ||= {}
  @writes ||= {}

  attrs.each do |attribute|
    attribute = attribute.to_sym

    attr_reader attribute unless @writes.key?(attribute)

    @reads[attribute] = :"@#{attribute}"
  end

  @reads
end

.writes(*attrs) ⇒ Object

Note:

You may not write to any slot in LifecycleVM::Memory::PROTECTED

Allow writing one or more values to vm memory and provide them as writeable attributes



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# File 'lib/lifecycle_vm/op_base.rb', line 60

def self.writes(*attrs)
  @reads ||= {}
  @writes ||= {}

  attrs.each do |attribute|
    attribute = attribute.to_sym
    raise InvalidAttr.new(self, attribute) if LifecycleVM::Memory::PROTECTED.include?(attribute)

    if @reads.key?(attribute)
      attr_writer attribute
    else
      attr_accessor attribute
    end

    @writes[attribute] = :"#{attribute}="
  end

  @writes
end

Instance Method Details

#call ⇒ Object 



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# File 'lib/lifecycle_vm/op_base.rb', line 115

def call; end

#error(field, message) ⇒ Object

Declare that an error has occurred.

Parameters:

  • field (Symbol) —

    the memory field which is in error. The convention is to use :base for errors not associated with any particular memory field.

  • message (Object) —

    a description of the error. Convention is to use a string.



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# File 'lib/lifecycle_vm/op_base.rb', line 124

def error(field, message)
  @errors ||= {}
  @errors[field] ||= []
  @errors[field] << message
end

#errors? ⇒ Boolean

Did any errors occur in the execution of this op?

Returns:

  • (Boolean) 


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# File 'lib/lifecycle_vm/op_base.rb', line 131

def errors?
  !(@errors.nil? || @errors.empty?)
end

#validate ⇒ Object 



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# File 'lib/lifecycle_vm/op_base.rb', line 116

def validate; end