greater_less

The GreaterLess class can be used to generate objects that represent halfopen intervals, but transparently behave as Floats. One easy way to integrate this class into your project is by requiring the greater_less string extension as follows:

require 'greater_less/string_extension'

This extension redifines the #to_f method of the String class as follows:

class String
  alias :to_f_without_greater_less :to_f

  def to_f
    if self =~ GreaterLess::GREATER_LESS
      return GreaterLess.new(self)
    end
    self.to_f_without_greater_less
  end
end

Now when a string starts with a greater or less sign (like for instance "> 3.45"), the #to_f method converts it to a GreaterLess object instead of the value 0.0.

With this extension in place one can simply convert strings like the one above to a float like object and compare it to floats as if it were a float itself. For instance one can do the following:

>> value = ">3.45".to_f
=> > 3.45
>> value > 2.45
=> true
>> value >= 2.45
=> true
>> 2.45 > value
=> false
>> 2.45 >= value
=> false
>> value == ">3.45".to_f
=> true
>> value != 2.45
=> true

It is also possible to compare GreaterLess values with each other, so you do not have to worry about what kind of object you are dealing with in your code:

>> value1 = ">3.45".to_f
=> > 3.45
>> value2 = "< 2.45".to_f
=> < 2.45
>> value1 > value2
=> true
>> value2 > value1
=> false

Finally it is possible to apply simple arithmetics to GreaterLess objects like addition, subtraction, multiplication and division:

>> value = ">3.45".to_f
=> > 3.45
>> value + 2
=> > 5.45
>> value - 2
=> > 1.4500000000000002
>> value * 2
=> > 1.725

Inverting the object’s sign when multiplying with a negative numerical or using a GreaterLess object in the denominator is nicely dealt with:

>> value = ">3.45".to_f
=> > 3.45
>> -1 * value
=> < -3.45
>> 1 / value
=> < 0.2898550724637681
>> -1 / value
=> > -0.2898550724637681

It makes no sense to apply the operators +, -, * or / on a pair of GreaterLess objects, so an exception is raised in these cases.

All other methods are simply passed to the float value the GreaterLess object contains, so that it transparently acts like a float.

Contributing to greater_less

Check out the latest master to make sure the feature hasn’t been implemented or the bug hasn’t been fixed yet.
Check out the issue tracker to make sure someone already hasn’t requested it and/or contributed it.
Fork the project.
Start a feature/bugfix branch.
Commit and push until you are happy with your contribution.
Make sure to add tests for it. This is important so I don’t break it in a future version unintentionally.
Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.

greater_less

Contributing to greater_less

Copyright