From: Chris Morris <chrismo@...>
Date: 2002-08-09T05:57:54+09:00
Subject: Variable validation

I've got a class that has a number of instance variables, some of which must
be set prior to calling a save function to write these off somewhere else.
I'm doing the following:

      def check_required
        if @password == nil or @password.empty?
          or @firstName == nil or @firstName.empty?
          or @lastName == nil or @lastName.empty?
          or @nickName == nil or @nickName.empty?
          or @email == nil or @email.empty?
          raise RequiredDataMissingError('')
      end

... but this smells.

I thought about putting them all in an array, then iterating over it -- one
downside is I can only put them in an array for the duration of the call
because:

irb(main):001:0> @a = 'hey'
"hey"
irb(main):002:0> @b = 'you'
"you"
irb(main):003:0> vars = [@a, @b]
["hey", "you"]
irb(main):004:0> @a = 'yo'
"yo"
irb(main):005:0> vars
["hey", "you"]

... shows that there's not a link kept between the @a in vars and @a.

I guess this is better:

      def check_required
        vars = {
          'password' => @password,
          'firstName' => @firstName,
          'lastName' => @lastName,
          'nickName' => @nickName,
          'email' => @email,
        }

        missing = ''
        vars.each do |name, value|
          missing << ', ' if !missing.empty?
          missing << name if value == nil || value.empty?
        end

        raise RequiredDataMissingError.new("Required fields not set:
#{missing}") if !missing.empty?
      end

Any better ideas?

Chris
http://clabs.org