calculator_controller.rb

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class CalculatorController < ApplicationController
	before_filter :set_charset 
	
	def set_charset 
		@headers["Content-Type"] = "text/html; charset=GB2312" 
	end 
	
	def calculate
		if request.post?
			@errors = []
			arg1 = convert_float(:arg1)
			arg2 = convert_float(:arg2)
			op = convert_operator(:operator)
			if @errors.empty?
				begin
					@result = op.call(arg1, arg2)
				rescue Exception => err
					@result = err.message
				end
			end
		end
	end
	private
	def convert_float(name)
		if params[name].blank?
			@errors << "#{name} 不能为空"
		else
			begin
				Float(params[name])
				rescue Exception => err
				@errors << "#{name}: 无法将输入数据转换为float型"
				nil
			end
		end
	end
	
	def convert_operator(name)
		case params[name]
			when "+" then proc {|a,b| a+b}
			when "-" then proc {|a,b| a-b}
			when "*" then proc {|a,b| a*b}
			when "/" then proc {|a,b| a/b}
		end
	end
end