Class: DynamicVariable

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

Direct Known Subclasses

Mixin::MixedDynamicVariable

Defined Under Namespace

Modules: Mixin

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*pairs, &block) ⇒ DynamicVariable

Returns a new instance of DynamicVariable.



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# File 'lib/dynamic_variable.rb', line 4

def initialize(*pairs, &block)
  self.default_variable = :value
  @bindings = []
  if block_given?
    with(*pairs, &block)
  else
    push_pairs(pairs) unless pairs.empty?
  end
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(variable, *args) ⇒ Object 



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# File 'lib/dynamic_variable.rb', line 58

def method_missing(variable, *args)    
  if args.empty?
    value = self[variable]
    instance_eval %Q{def #{variable}; self[:#{variable}] end}
  else
    writer = variable
    unless args.size == 1 and writer.to_s =~ /(.*)=/
      raise NoMethodError,
        "undefined method `#{writer}' for #{self.inspect}"
    end
    variable = $1.to_sym
    self[variable] = args[0]
    instance_eval %Q{def #{writer}(v); self[:#{variable}] = v end}
  end
  value
end

Instance Attribute Details

#default_variable ⇒ Object

Returns the value of attribute default_variable.



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# File 'lib/dynamic_variable.rb', line 2

def default_variable
  @default_variable
end

Instance Method Details

#[](variable) ⇒ Object 



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# File 'lib/dynamic_variable.rb', line 50

def [](variable)
  find_binding(variable)[1]
end

#[]=(variable, value) ⇒ Object 



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# File 'lib/dynamic_variable.rb', line 54

def []=(variable, value)
  find_binding(variable)[1] = value
end

#bindings(variable = (un = true)) ⇒ Object 



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# File 'lib/dynamic_variable.rb', line 85

def bindings(variable = (un = true))
  if un
    @bindings.map{|pair| pair.clone}
  else
    @bindings.select{|var, value| var == variable}.map!{|var, value| value}
  end
end

#bindings=(bindings) ⇒ Object 



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# File 'lib/dynamic_variable.rb', line 93

def bindings=(bindings)
  set_bindings(bindings)
end

#pop(variable) ⇒ Object 



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# File 'lib/dynamic_variable.rb', line 20

def pop(variable)
  index = rindex(variable)
  @bindings.slice!(index)[1] if index
end

#push(variable, value) ⇒ Object 



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# File 'lib/dynamic_variable.rb', line 14

def push(variable, value)
  pair = [variable, value]
  @bindings << pair
  pair
end

#set_bindings(variable, bindings = (un = true)) ⇒ Object 



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# File 'lib/dynamic_variable.rb', line 97

def set_bindings(variable, bindings = (un = true))
  if un
    bindings = variable
    @bindings = bindings.map do |pair|
      unless pair.is_a? Array and pair.size == 2
        raise ArgumentError,
          "expected [variable, value] pair, got #{pair.inspect}"
      end
      pair.clone
    end
  else
    unless bindings.is_a? Array
      raise ArgumentError,
        "expected bindings to be Array, got a #{bindings.class}"
    end
    index = 0
    old_bindings = @bindings
    @bindings = []
    old_bindings.each do |var, value|
      if var == variable
        unless index < bindings.size
          next
        end
        value = bindings[index]
        index += 1
      end
      push(var, value)
    end
    while index < bindings.size
      value = bindings[index]
      push(variable, value)
      index += 1
    end
  end
  bindings
end

#variables ⇒ Object 



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# File 'lib/dynamic_variable.rb', line 75

def variables
  variables = {}
  @bindings.each{|variable, value| variables[variable] = value}
  variables
end

#variables=(variables) ⇒ Object 



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# File 'lib/dynamic_variable.rb', line 81

def variables=(variables)
  variables.each{|variable, value| self[variable] = value}
end

#with(*pairs) ⇒ Object

with {} varible defaults to default_variable value defaults to nil

with(value) { block } variable defaults to default_variable

with(variable, value) { block }

with(variable_1, value_1, ..., variable_n_1, value_n_1, value_n) { block } variable_n defaults to default_variable

with(variable_1, value_1, ..., variable_n, value_n) { block }



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# File 'lib/dynamic_variable.rb', line 40

def with(*pairs)
  pairs = [nil] if pairs.empty?
  begin
    push_pairs(pairs)
    yield(self)
  ensure
    pop_pairs(pairs)
  end
end