Class: MethodHash

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(path = nil) ⇒ MethodHash

— initialize — A path is optional but necessary if you want to store the Hash to disk.



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# File 'lib/methodhash.rb', line 11

def initialize(path=nil)
  unless self.respond_to? :mymethod
    raise ArgumentError, 
          "No calculation method (with name 'mymethod') defined for #{self.class}"
  end
  if self.class.to_s == 'MethodHash'
    raise ArgumentError, "Make a subclass. Don't use MethodHash directly."
  end
  @path = path
  @changed = false 
  @retry_errors = false
  @force_calc = false
  if @path and File.exists? @path
    hash = YAML.load open(@path)
    raise ArgumentError, "Path holds class #{hash.class}" if hash.class != self.class
    self.merge! hash
  end
end

Instance Attribute Details

#changed ⇒ Object (readonly)

Returns the value of attribute changed.



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# File 'lib/methodhash.rb', line 6

def changed
  @changed
end

#force_calc ⇒ Object

Returns the value of attribute force_calc.



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# File 'lib/methodhash.rb', line 5

def force_calc
  @force_calc
end

#path ⇒ Object (readonly)

Returns the value of attribute path.



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# File 'lib/methodhash.rb', line 6

def path
  @path
end

#retry_errors ⇒ Object

Returns the value of attribute retry_errors.



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# File 'lib/methodhash.rb', line 5

def retry_errors
  @retry_errors
end

Instance Method Details

#[](*arg) ⇒ Object

— [] — If not previously called with given arguments, calls ‘mymethod’ with the arguments and inserts the answer in the Hash. If force_calc is set to true, mymethod is always called. If retry_errors is set to true, mymethod is also called if value has previously been retrieved but raised an error at that time.



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# File 'lib/methodhash.rb', line 36

def [](*arg)
  arg = arg.first if arg.size==1
  if !force_calc and s=super(arg)
    if s.is_a? String and s[0,6]=='ERROR:'
      if @retry_errors
        self.delete arg
        self.[](*arg)
      else
        raise s[7..-1]
      end
    else
      s
    end
  else
    @changed = true
    begin
      originalassign(arg,self.mymethod(*arg))
    rescue
      originalassign(arg,"ERROR: #{$!}")
      raise
    end
  end
end

#[]=(key, value) ⇒ Object

— []= — This method cannot be used.



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# File 'lib/methodhash.rb', line 62

def []=(key, value)
  raise "You can't just put values into a #{self.class}."
end

#changed? ⇒ Boolean

— changed? — Has something changed since the last call to dump?

Returns:

  • (Boolean) 


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# File 'lib/methodhash.rb', line 89

def changed?
  @changed
end

#delete(arg) ⇒ Object 



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# File 'lib/methodhash.rb', line 82

def delete(arg)
  @changed = true
  super
end

#dump ⇒ Object

— dump — If a path has been given, writes self to that file and returns the path. Otherwise, returns a string containing the dump.



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# File 'lib/methodhash.rb', line 69

def dump
  if @path
    if self.changed?
      open(@path,'w'){|f| YAML.dump(self,f) }
      @changed = false
    end
    @path
  elsif !path
    @changed = false
    YAML.dump(self)
  end
end

#originalassign ⇒ Object 



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# File 'lib/methodhash.rb', line 7

alias_method :originalassign, :[]=