Ruby Method example

methods-example.rb

# Get the set of method symbols that end in ?
predicatesSymbols = 1.methods.select { |x| if x.to_s =~ /.*\?/ then true end }
# For each symbol, get the `Method` object corresponding to that symbol
methods = predicatesSymbols.map { |symbol| 1.method(symbol) }
# Filter out methods that don't accept one argument
resultingValues = methods.map do |meth|
  begin
    # Create an array of arguments to call the method with, using
    # `arity` to look up how many parameters it expects.
    a = Array.new(meth.arity,1)
    # Return the method's name and the result of calling it with
    # `arity` ones
    [meth.name,meth.call(*a)]
  rescue
    # This could crash because there could be a type error, in that
    # case just return `nil` and we'll filter it out in the next step
    nil
  end
end
# Filter out errors
resultingValues.select! { |x| x }
# Print out each predicate and its corresponding result after calling
resultingValues.each { |x| puts "Method #{x[0]} returned #{x[1]}" }