Class: MethodArgs

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

Overview

Code to extract the formal parameter names and types from a function given a standard Ruby function argument signature. Original code based on the MethodArgs module written by Mauricio Fernandez <[email protected]> (eigenclass.org). Updated to work with function signatures added at runtime, also, peroperly handles block arguments.

Author

Jim Powers ([email protected])

Copyright

Copyright © 2008-2009 Jim Powers

License

Distributed under the terms of the LGPLv3.0 or newer. For details see the LGPL30 file

Example:

require ‘method_args’ MethodArgsHelper.get_args(“a, b = {}, *c, &d”)

> [“a”, “b”, “*c”, “&d”]

Very useful for building proxy functions that call an underlying function

Constant Summary collapse

MAX_ARGS = 
20

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#params ⇒ Object (readonly)

Returns the value of attribute params.



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# File 'lib/method_args.rb', line 22

def params
  @params
end

Instance Method Details

#output_method_info(klass, object, meth, is_singleton = false) ⇒ Object 



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# File 'lib/method_args.rb', line 24

def output_method_info(klass, object, meth, is_singleton = false)
  @params = nil
  @values = nil
  num_args = 0
  unless %w[initialize].include?(meth.to_s)
    if is_singleton
      return if class << klass; private_instance_methods(true) end.include?(meth.to_s)
    else
      return if class << object; private_instance_methods(true) end.include?(meth.to_s)
    end
  end
  arity = is_singleton ? object.method(meth).arity : klass.instance_method(meth).arity
  set_trace_func lambda{|event, file, line, id, binding, classname|
    begin
      if event[/call/] && classname == MethodArgsHelper && id == meth
        @params = eval("local_variables", binding)
        @values = eval("local_variables.map{|x| eval(x)}", binding)
        throw :done
      end
    rescue Exception
    end
  }
  if arity >= 0
    num_args = arity
    catch(:done){ object.send(meth, *(0...arity)) }
  else
    # determine number of args (including splat & block)
    MAX_ARGS.downto(arity.abs - 1) do |i|
      catch(:done) do
        begin
          object.send(meth, *(0...i))
        rescue Exception
        end
      end
      next if !@values || @values.compact.empty?
      k = nil
      @values.each_with_index{|x,j| break (k = j) if Array === x}
      if k
        num_args = k+1
      else
        num_args = i
      end
    end
    args = (0...arity.abs-1).to_a
    catch(:done) do
      args.empty? ? object.send(meth) : object.send(meth, *args)
    end
  end
  set_trace_func(nil)
  fmt_params = lambda do |arr, arity|
    arr.inject([[], 0]) do |(a, i), x|
      if Array === @values[i]
        [a << "*#{x}", i+1]
      else
        [a << x, i+1]
      end
    end.first
  end
  original_params = @params
  @params ||= []
  @params = @params[0,num_args]
  @params = fmt_params.call(@params,arity)
  if @params.length < original_params.length
    @params << "&#{original_params[-1]}"
  end
  set_trace_func(nil)
end