yield in ERB without rails

Question

How can I use yield for template inheritance in erb? I want to use erb in a plain ruby CGI script and want to use a base template and subtemplate like it Rails wit

Answer 1

def a
  ERB.new('<%= yield %>').result(binding)
end
a{123}
#=> "123"

It's important that the call to Kernel#binding be inside a method, that way the context includes the block (ERB#result won't take a block).