Class: Environment

Inherits:
Object show all
Defined in:
lib/forsta/environment.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(parent = nil, defaults = {}) ⇒ Environment

Returns a new instance of Environment.



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# File 'lib/forsta/environment.rb', line 4

def initialize(parent=nil, defaults={})
  @parent = parent
  @defaults = defaults
end

Instance Attribute Details

#defaults ⇒ Object (readonly)

Returns the value of attribute defaults.



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# File 'lib/forsta/environment.rb', line 2

def defaults
  @defaults
end

#parent ⇒ Object (readonly)

Returns the value of attribute parent.



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# File 'lib/forsta/environment.rb', line 2

def parent
  @parent
end

Instance Method Details

#define(symbol, value) ⇒ Object 



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# File 'lib/forsta/environment.rb', line 9

def define(symbol, value)
  defaults[symbol] = value
end

#defined?(symbol) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/forsta/environment.rb', line 13

def defined?(symbol)
  defaults.has_key?(symbol) || (parent && parent.defined?(symbol))
end

#lookup(symbol) ⇒ Object 



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# File 'lib/forsta/environment.rb', line 17

def lookup(symbol)
  defaults[symbol] || (parent && parent.lookup(symbol)) ||
    raise("#{symbol} is undefined")
end

#set(symbol, value) ⇒ Object 



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# File 'lib/forsta/environment.rb', line 22

def set(symbol, value)
  if defaults.has_key?(symbol)
    defaults[symbol] = value
  elsif parent.nil?
    raise("#{symbol} was undefined")
  else
    parent.set(symbol, value)
  end
end