Question

I’m trying to create “autorequire” for a package, namely if Ruby encounters an unknown constant it tries to require it, and continues where it left off if the require succeeds. Now I have something like this:

def autoload(&block)
  yield
rescue NameError => e
  if e.message[/constant/]
    require e.name.to_s.downcase rescue LoadError raise
    retry
  end
  raise
end

So if I use this like

autoload {
   print "Hello, "
   x = ArrayFields.new
   x << "World!"
   puts x[0]
}

As expected, it will print Hello, Hello, World!. So it handles the requiring of the constant, but executes the entire given block from the beginning. So how do I skip to where the fail occurred? This is mostly for academic interest, so I’m also interested in any dangers in attempts like this.

Answer 1

It is not possible to jump back to the point right before the exception from a rescue-clause. A more feasible approach to do what you want would be to override const_missing.