While doing some work with define_method today, I was looking for a way to specify blocks with default argument values so that I could define methods with default argument values.  It seems that Ruby doesn’t support this doing this:

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# Does NOT work
define_method :method_name do |first_arg=“default1”, second_arg=“default2”|
  # …
end
  		 
This is mainly because of some limitations with yacc, which Ruby uses (says matz):
  
  
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Mostly because yacc does not allow it.  It confuses
 lambda { |foo = bar| puts foo }
as
 lambda { |foo = (bar| puts foo) }
and causes syntax error.
 
  		 
Anyways, I’ve found that these two approaches work:
 
  
  
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# Using optional arguments, with a default value for “two”
define_method :method_name do |required, *optional|
  # one, two, = *optional
  one, two, *ignored = *optional
  # two will have a default value
  two ||= “Default value”
  
  # …
end
 
# With an options hash, with default values for the options
define_method :method_name do |required, *options|
  default_options = { :foobar => “default value }
  options = (options.first || Hash.new).merge(default_options)
  foobar = options[:foobar]
 
  …
end
 
  		 
 I wonder if anybody has a better way to do this
      
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