class Facter::Util::Resolution

This represents a fact resolution. A resolution is a concrete implementation of a fact. A single fact can have many resolutions and the correct resolution will be chosen at runtime. Each time {Facter.add} is called, a new resolution is created and added to the set of resolutions for the fact named in the call. Each resolution has a {#has_weight weight}, which defines its priority over other resolutions, and a set of {#confine confinements}, which defines the conditions under which it will be chosen. All confinements must be satisfied for a fact to be considered suitable.

@api public

Attributes

code[RW]

@api private

fact[R]

@!attribute [r] fact @return [Facter::Util::Fact] @api private

name[RW]

@!attribute [rw] name The name of this resolution. The resolution name should be unique with respect to the given fact. @return [String] @api public

value[W]

Public Class Methods

new(name, fact) click to toggle source

Create a new resolution mechanism.

@param name [String] The name of the resolution. @return [void]

@api private

# File lib/facter/util/resolution.rb, line 56
def initialize(name, fact)
  @name = name
  @fact = fact
  @confines = []
  @value = nil
  @timeout = 0
  @weight = nil
end

Public Instance Methods

evaluate(&block) click to toggle source

Evaluate the given block in the context of this resolution. If a block has already been evaluated emit a warning to that effect.

@return [void]

# File lib/facter/util/resolution.rb, line 73
def evaluate(&block)
  if @last_evaluated
    msg = "Already evaluated #{@name}"
    msg << " at #{@last_evaluated}" if msg.is_a? String
    msg << ", reevaluating anyways"
    Facter.warn msg
  end

  instance_eval(&block)

  # Ruby 1.9+ provides the source location of procs which can provide useful
  # debugging information if a resolution is being evaluated twice. Since 1.8
  # doesn't support this we opportunistically provide this information.
  if block.respond_to? :source_location
    @last_evaluated = block.source_location.join(':')
  else
    @last_evaluated = true
  end
end
resolution_type() click to toggle source
# File lib/facter/util/resolution.rb, line 65
def resolution_type
  :simple
end
set_options(options) click to toggle source
# File lib/facter/util/resolution.rb, line 93
def set_options(options)
  if options[:name]
    @name = options.delete(:name)
  end

  if options.has_key?(:value)
    @value = options.delete(:value)
  end

  if options.has_key?(:timeout)
    @timeout = options.delete(:timeout)
  end

  if options.has_key?(:weight)
    @weight = options.delete(:weight)
  end

  if not options.keys.empty?
    raise ArgumentError, "Invalid resolution options #{options.keys.inspect}"
  end
end
setcode(string = nil, &block) click to toggle source

Sets the code block or external program that will be evaluated to get the value of the fact.

@return [void]

@overload setcode(string)

Sets an external program to call to get the value of the resolution
@param [String] string the external program to run to get the
  value

@overload setcode(&block)

Sets the resolution's value by evaluating a block at runtime
@param [Proc] block The block to determine the resolution's value.
  This block is run when the fact is evaluated. Errors raised from
  inside the block are rescued and printed to stderr.

@api public

# File lib/facter/util/resolution.rb, line 132
def setcode(string = nil, &block)
  if string
    @code = Proc.new do
      output = Facter::Core::Execution.execute(string, :on_fail => nil)
      if output.nil? or output.empty?
        nil
      else
        output
      end
    end
  elsif block_given?
    @code = block
  else
    raise ArgumentError, "You must pass either code or a block"
  end
end