2010-02-06

Backward compatibility for Ruby 1.8

As I'm currently writing some Ruby code and that I started with version 1.9 I felt onto cases where some methods don't exist for Ruby 1.8. This is very annoying and I started by switching the code to 1.8 method calls. I disliked this when it came to Process.spawn which is a one line call to execute a separate process. Rewriting it takes around 5 lines instead.

So I had the idea to reuse something I already saw once. I write a new file named compat18.rb and include it within the sources that need it. Ruby makes it very easy to add new methods to existing classes/modules anyway, even if they exist already, so I just did it and it works like a charm.

Here is a small snippet:
class Array
        def find_index(idx)
                index(idx)
        end
end

class Dir
        def exists?(path)
                File.directory?(path)
        end
end

Update: It can happen that a fallback method from Ruby 1.8 has been totally dropped and replaced against a new method in 1.9, and in this case the older method has to be checked if it exists, and otherwise make a call to the parent.
class Array
        def count
                if defined? nitems
                        return nitems
                else
                        return super
                end
        end
end

1 comment: