use check_param_presence? method to check default param

lib/rails_param/param.rb

@@ -15,12 +15,11 @@ module RailsParam
     def param!(name, type, options = {}, &block)
       name = name.to_s unless name.is_a? Integer # keep index for validating elements
       
-      
-      return unless params.member?(name) || (not options[:default].nil?) || options[:required]
+      return unless params.member?(name) || check_param_presence?(options[:default]) || options[:required]
 
       begin
         params[name] = coerce(params[name], type, options)
-        params[name] = (options[:default].call if options[:default].respond_to?(:call)) || options[:default] if params[name].nil? and (not options[:default].nil?)
+        params[name] = (options[:default].call if options[:default].respond_to?(:call)) || options[:default] if params[name].nil? and check_param_presence?(options[:default])
         params[name] = options[:transform].to_proc.call(params[name]) if params[name] and options[:transform]
         validate!(params[name], options)
 
@@ -66,6 +65,10 @@ module RailsParam
 
     private
 
+    def check_param_presence? param
+      not param.nil?
+    end
+
     def recurse(params, index = nil)
       raise InvalidParameterError, 'no block given' unless block_given?
       controller = RailsParam::Param::MockController.new