Builder's XmlMarkup object loses constants? - ruby

Question

I try to upgrade a legacy application from Ruby 1.8.7 to 2.2.3. Afterwards the rendering of builder templates raises errors about unknown classes.
uninitialized constant Builder::XmlMarkup::BigDecimal (NameError)
It seem that within the Builder::XmlMarkup constants like classes disappear.
### example.xml.builder (template) ###
BigDecimal.new('23') # no error
class << xml
def some
data(BigDecimal.new('23')) # raises an error in 2.2.3
end
end
xml.test { xml.some }
### main script ###
require 'rubygems'
require 'builder'
require 'bigdecimal'
def eval_script(file)
xml = Builder::XmlMarkup.new
binding.eval(File.read(file), file)
xml.target!
end
template = File.join(File.dirname(__FILE__), 'example.xml.builder')
puts eval_script(template)
# Ruby 1.8.7 / builder 3.2.0 => <test><data>0.23E2</data></test>
# Ruby 2.2.3 / builder 3.2.2 => ./eval_script.rb:5:in `some': uninitialized constant Builder::XmlMarkup::BigDecimal (NameError)
I found no reason for the behavior. How can I fix the problem?
BTW: I have the same problem with the method lookup, e.g format('%d', 42) which returns the full XML document but doesn't call Kernel.format in Ruby 2.2.3.

Answer 1

I found a workaround overriding const_missing which has to be applied to every template file. It works so far for the legacy application.
### example.xml.builder (template) ###
class << xml
def self.const_missing(name)
super rescue ::Object.const_get(name)
end
def some
data(BigDecimal.new('23'))
end
end
xml.test { xml.some }
But every time the constant BigDecimal is used, it triggers const_missing and then raises a NameError and calls the Object method.