Rails 3: getting undefined method when trying to use a variable in a block

I'm getting undefined method 'social_system' for #User:0x000001052e2ad8. I thought i'd be using the value in the block, can anyone explain what I'm doing wrong?

# User model:
facebook_url    string
google_plus_url string

# Con开发者_StackOverflowstants defined in User model:
SOCIAL_SYSTEMS      = [ 'facebook_url', 'google_plus_url' ]
SOCIAL_SYSTEM_NAMES = { 'facebook_url'    => 'Facebook',
                        'google_plus_url' => 'Google +' }

# View (going to be a helper eventually)
<%  User::SOCIAL_SYSTEMS.each do |social_system| 
      url = @user.send(social_system)
      if url %>
        <p><a href="<%= url %>">
          <%= User::SOCIAL_SYSTEM_NAMES[social_system] -%>
        </a></p>
<%    end
    end
%>

Hmmm, since the error msg is

undefined method 'social_system' for #User:0x000001052e2ad8.

that implies that "social_system" is being treated as a string const, not as a variable.

Try echoing it to see what is being sent. The variable social_system should only have values of 'facebook_url', 'google_plus_url'

Echo test:

# View (going to be a helper eventually)
<%  User::SOCIAL_SYSTEMS.each do |social_system| 
%>
<p>social_system = <%= social_system %> 
<% #      url = @user.send(social_system)
   #   if url %>
   #     <p><a href="<%= url %>">
          <%= User::SOCIAL_SYSTEM_NAMES[social_system] -%>
        </a></p>
<% #   end
    end
%>