Load Ruby gem into a user-defined namespace

Question

Given a gem that defines top-level classes that clash with some code I have written, is it possible to require the gem in such a way that all its classes are grouped inside a module I can define? For example, if an unsafe_gem defines a class:

class Word
  # ... some code
end

I would need something like:

class Word
  # My word class.
end

module SafeContainer
  # This obviously doesn't work
  # (i.e. the gem still defines ::Word).
  require 'unsafe_gem'
end

So that I can distinguish between:

Word.new # => The class I defined.
SafeContainer::Word.new # => The class defined by the gem.

Some further details: My code (e.g. the 'Word' class) is already wrapped in its own namespace. However, I want to be able to provide the user with the option of enabling a form of "syntactic sugar", which makes some classes directly accessible under the top-level namespace. This, however, creates a name clash with one of the gems I am using, which defines a top-level class. None of the currently proposed solutions work because the gem actually relies on its globally-defined class being there; so undefining the class breaks the gem. Of course, the gem has more than one file, and individually requiring its files into a module seems to be a very brittle solution. Currently, the only workaround I have found is this:

begin
  # Require the faulty gem.
  require 'rbtagger'
rescue 
  # If syntactic sugar is enabled...
  if NAT.edulcorated?
    # Temporarily remove the sugar for the clashing class.
    Object.const_unset(:Word); retry
  else; raise; end
ensure
  # Restore syntactic sugar for the clashing class.
  if NAT.edulcorated?
    Object.const_set(:Word, NAT::Entities::Word)
  end
end

I don't know why, but this makes my toenails curl. Anybody have a better solution?

score 5 · Accepted Answer · edited May 23 '17 at 12:32

5

Another, possibly better answer, comes from this question.

Take advantage of the fact that classes and modules are just objects, like so:

require 'unsafe_gem'
namespaced_word = Word
Word = nil


# now we can use namespaced_word to refer to the Word class from 'unsafe_gem'

#now your own code
class Word
  #awesome code
end

You have to make sure that unsafe_gem only defines one class, and that you require it before you define your own classes and modules so you don't accidentally set your own stuff to nil.

edited May 23 '17 at 12:32

Community

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answered Jan 06 '12 at 18:38

Jamison Dance

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1

Where would one have to put that in order to work? Is this an initializer? Is this a file in /lib? I am tried creating an initializer, but I get "cannot load such file". EDIT: Never had to include a gem before. I put underscores instead of dashed and it went away. Not sure if that makes it actually work though. – Tashows Dec 23 '20 at 08:54

score 1 · Answer 2 · answered Jan 06 '12 at 18:31

I think your best bet is to wrap your own code in a module. Depending on how much code you have written, this may or may not be a huge pain. However, it is the best way to be sure that your code won't clash with someone else's.

So your Word class becomes

module LoismsProject
  class Word
    #some awesome code
  end
end

That way you can safely require 'unsafe_gem'.

score 1 · Answer 3 · answered Jan 06 '12 at 18:37

The simple answer is "no"

If we have a file 'word.rb';

class Word
  def say
    puts "I'm a word"
  end
end

and we try and require it, it will always load in the global scope.

If you knew the gem was just a single file, you could, however do the following.

module SafeContainer
  module_eval(File.read("word.rb"))
end

but this is unlikely to work in your case.

Load Ruby gem into a user-defined namespace

3 Answers3

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