Inheritance (sub class from Unit) no longer works

[kreintjes]

In our app we create a sub class from Unit to apply some custom behaviour (#240 (comment)). This worked fine Ruby-Units 3.0 and before, but stopped working since Ruby-Units 4.0. If we try this now every .new call crashes with a undefined method keys' for nil:NilClass (NoMethodError)error inunit.rb:363:in unit_regex. This essentially breaks the functionality introduced in #241.

To reproduce:

Add Ruby-Units 4.0.x to the Gemfile, and execute the following:

class ChildUnit < Unit; end
ChildUnit.new('1 l')

We are suspecting this has something to do with the refactor in #274. Any suggestions on how to fix this would be welcome!

[olbrich]

@kreintjes Confirmed, I'll look into this soon.

[olbrich]

@kreintjes Please take a look at the associated PR and give it a shot. Let me know if it fixes your issues.

Out of curiosity, what is motivating you to create a subclass?

[kreintjes]

@olbrich I tried it both in my sample project as well as in our real project and it both works great! Thanks for the quick fix!

We use a sub class of RubyUnits to override the eliminate_terms method with a simpler variant that does less simplification of the units after applying operations. E.g. when having Unit.new('10 l') / Unit.new('5 l') we leave this as 2 l/l instead of 2. See #240 for details.

[kreintjes]

Nice you released this so quickly @olbrich! ❤️