I have a command line Ruby app I'm developing and I want to allow a user of it to provide code that will run as a filter on part of the process. Basically, the application does this:
- read in some data
- If a filter is specified, use it to filter data
- process the data
I want the filtering process (step 2) to be as flexible as possible.
My thinking was that the user could provide a Ruby file that set a known constant to point to an object implementing an interface I define, e.g.:
# user's filter class MyFilter def do_filter(array_to_filter) filtered_array = Array.new # do my filtering on array_to_filter filtered_array end FILTER = MyFilter.new
My app's code would then do something like this:
array_that_might_get_filtered = get_my_array() if (options.filter_file) require options.filter_file array_that_might_get_filtered = FILTER.do_filter(array_that_might_get_filtered) end
While this would work, it feels cheesy and it seems like there should be a better way to do it. I also considered having the filter be in the form of adding a method of a known name to a known class, but that didn't seem quite right, either.
Is there a better idiom in Ruby for this?