Class: Vagrant::Plugin::V2::Config

Inherits:
Object
  • Object
show all
Defined in:
lib/vagrant/plugin/v2/config.rb

Overview

This is the base class for a configuration key defined for V2. Any configuration key plugins for V2 should inherit from this class.

Constant Summary collapse

UNSET_VALUE =

This constant represents an unset value. This is useful so it is possible to know the difference between a configuration value that was never set, and a value that is nil (explicitly). Best practice is to initialize all variables to this value, then the #merge method below will “just work” in many cases.

Object.new

Instance Method Summary collapse

Instance Method Details

#finalize! ⇒ Object

This is called as a last-minute hook that allows the configuration object to finalize itself before it will be put into use. This is a useful place to do some defaults in the case the user didn’t configure something or so on.

An example of where this sort of thing is used or has been used: the “vm” configuration key uses this to make sure that at least one sub-VM has been defined: the default VM.

The configuration object is expected to mutate itself.



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# File 'lib/vagrant/plugin/v2/config.rb', line 25

def finalize!
  # Default implementation is to do nothing.
end

#instance_variables_hash ⇒ Object

Returns the instance variables as a hash of key-value pairs.



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# File 'lib/vagrant/plugin/v2/config.rb', line 83

def instance_variables_hash
  instance_variables.inject({}) do |acc, iv|
    acc[iv.to_s[1..-1]] = instance_variable_get(iv)
    acc
  end
end

#merge(other) ⇒ Object

Merge another configuration object into this one. This assumes that the other object is the same class as this one. This should not mutate this object, but instead should return a new, merged object.

The default implementation will simply iterate over the instance variables and merge them together, with this object overriding any conflicting instance variables of the older object. Instance variables starting with “__” (double underscores) will be ignored. This lets you set some sort of instance-specific state on your configuration keys without them being merged together later.

Parameters:

  • other (Object) —

    The other configuration object to merge from, this must be the same type of object as this one.

Returns:

  • (Object) —

    The merged object.



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# File 'lib/vagrant/plugin/v2/config.rb', line 43

def merge(other)
  result = self.class.new

  # Set all of our instance variables on the new class
  [self, other].each do |obj|
    obj.instance_variables.each do |key|
      # Ignore keys that start with a double underscore. This allows
      # configuration classes to still hold around internal state
      # that isn't propagated.
      if !key.to_s.start_with?("@__")
        # Don't set the value if it is the unset value, either.
        value = obj.instance_variable_get(key)
        result.instance_variable_set(key, value) if value != UNSET_VALUE
      end
    end
  end

  result
end

#set_options(options) ⇒ Object

Allows setting options from a hash. By default this simply calls the ‘#key=` method on the config class with the value, which is the expected behavior most of the time.

This is expected to mutate itself.

Parameters:

  • options (Hash) —

    A hash of options to set on this configuration key.



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# File 'lib/vagrant/plugin/v2/config.rb', line 71

def set_options(options)
  options.each do |key, value|
    send("#{key}=", value)
  end
end

#to_json(*a) ⇒ Object

Converts this configuration object to JSON.



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# File 'lib/vagrant/plugin/v2/config.rb', line 78

def to_json(*a)
  instance_variables_hash.to_json(*a)
end

#validate(machine) ⇒ Hash

Called after the configuration is finalized and loaded to validate this object.

Parameters:

  • machine (Machine) —

    Access to the machine that is being validated.

Returns:

  • (Hash) 


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# File 'lib/vagrant/plugin/v2/config.rb', line 96

def validate(machine)
end