I’m talking about import at PyCon in April. In the talk, we’ll imagine that there is no import and will reinvent it from scratch. I hope this will give everyone (including me!) a deeper understanding of the choices import makes and the ways it could have been different. Ideally, the structure will be a couple of sections of the form “We could have made [decisions]. That would mean [effects]. Surprise – that’s how it works in [language]!”¹

This is the first of (probably) several posts with notes of things I’m learning as I prepare my talk. Feedback is welcome.

Today I’m looking into Ruby’s require and require_relative² to see if aspects of them would be interesting to Python programmers. So far, here’s what I think is most relevant:

• Unlike Python, require won’t load all objects in the required file. There’s a concept of local versus global variables in the file scope that doesn’t exist in Python.

• Unlike Python, one file does not map to one module. Modules are created by using the keyword module.

• Unlike Python, namespace collisions are completely possible. Consider the following simple files:

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puts "one!"

def foo
  :hello
end

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puts "two!"

def foo
  :world
end

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require_relative 'one'
require_relative 'two'

puts foo

And the output from running main.rb:

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one!
two!
world

• Like Python’s import, require will only load a file once. This can interact interestingly with namespace collisions – to take a contrived example:

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require_relative 'one'
require_relative 'two'
require_relative 'one'

puts foo

Because one.rb isn’t reloaded, foo is still 'world':

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one!
two!
world

Questions for further investigation / thought

My talk should not convince people that Python is Right and other languages are Wrong. I’m trying to overcome my bias towards the system I’m most used to. (I think I’ve written roughly equal amounts of Python and Ruby, but the vast majority of the Ruby I’ve written is Rails, where all the requireing and namespacing happens by magic.) Here are some questions I’d like to research more.

1. Python’s namespacing feels much better to me, although I’m sure that’s partly because I’m used to it. What’s the advantage to doing namespacing this way?

2. Why have both require and require_relative? Why not have require check the relative path as well before raising a LoadError?

3. What’s the advantage of uncoupling a module from a file?