Class: Factbase::Undef

Inherits:

TermBase

• Object
• TermBase
• Factbase::Undef

Defined in:

lib/factbase/terms/undef.rb

Overview

License

MIT

Instance Method Summary

• #evaluate(_fact, _maps, _fb) ⇒ Boolean

  Evaluate term on a fact.

• #initialize(operands) ⇒ Undef constructor

  Constructor.

Methods included from TermShared

#to_s

Constructor Details

#initialize(operands) ⇒ Undef

Constructor.

Parameters:

• operands (Array) —

  Operands

# File 'lib/factbase/terms/undef.rb', line 14

def initialize(operands)
  super()
  @operands = operands
end

Instance Method Details

#evaluate(_fact, _maps, _fb) ⇒ Boolean

Evaluate term on a fact.

Parameters:

• _fact (Factbase::Fact) —

  The fact

• _maps (Array<Factbase::Fact>) —

  All maps available

• _fb (Factbase) —

  Factbase to use for sub-queries

Returns:

• (Boolean) —

  True if definition is successfully removed.

# File 'lib/factbase/terms/undef.rb', line 24

def evaluate(_fact, _maps, _fb)
  assert_args(1)
  fn = @operands[0]
  raise "A symbol expected as first argument of 'undef'" unless fn.is_a?(Symbol)
  if Factbase::Term.private_instance_methods(false).include?(fn)
    Factbase::Term.class_eval("undef :#{fn}", __FILE__, __LINE__ - 1) # undef :foo
  end
  true
end