Module: Lemo::Memo::ClassMethods

Defined in:
lib/lemo/memo.rb

Instance Method Summary collapse

Instance Method Details

#ivar_from(maybe_meth) ⇒ Object

provide a legal ivar name from a method name. instance variables can’t have ? ! and other punctuation. Which isn’t handled. Obviously.



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# File 'lib/lemo/memo.rb', line 16

def ivar_from( maybe_meth )
  :"@_memo_#{maybe_meth.to_s.tr ILLEGAL_IVAR_CHARS,'pi'}"
end

#lemo(meth) ⇒ Object Also known as: memo 



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# File 'lib/lemo/memo.rb', line 20

def lemo( meth )
  unbound_previous_method = instance_method meth

  # still doesn't prevent memoisation of methods with an implicit block
  unless unbound_previous_method.parameters.empty?
    raise ArgumentError, "can't memo #{meth} with parameters"
  end

  memoed_methods[meth] = unbound_previous_method
  ivar = ivar_from meth

  define_method meth do
    # This gets executed on every call to meth, so make it fast.
    if instance_variable_defined? ivar
      instance_variable_get ivar
    else
      # bind the saved method to this instance, call the result ...
      to_memo = unbound_previous_method.bind( self ).call
      # ... memo it and return value
      instance_variable_set ivar, to_memo
    end
  end

  meth
end

#memoed_methods ⇒ Object 



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# File 'lib/lemo/memo.rb', line 10

def memoed_methods
  @memoed_methods ||= {}
end