Reusing allows one to use refinements directly from an extension file.
require 'reusing' using 'some_extension_script'
Ruby introduced refinements in version 2.0. Refinements are essentially a safe alternative to monkey-patching. Unfortunately, a serious problem with the syntax of refinements is the degree to which they differ from writing tradition class extensions. Traditionally, if you want to add a method to the String class, for instance, you simply open the class and define them method.
class String def some_method ... end end
And that's it. You could put that code in a file and require as needed. Refinements, on the other hand, hand much more boiler-plate. The above would have to be written:
module SomeModule refine String do def some_method ... end end end using SomeModule
This can be put in a file too, but the
using SomeModule will have to
be reissued in every file the refinement is needed.
For a one off use, this isn't a big deal. But for a method library such as Ruby Facets, this has huge implications. In fact, Facets does not yet support refinements precisely b/c of this issue. To do so would require maintaining a second copy of every method in refinement format. While doable, it is obviously not DRY, and quite simply a pain in the ass.
So the idea of overriding the
using method to accept a library file name was
hatched. With it, most extension scripts can be readily used as-is, without all
the boiler-plate. Usage is pretty simple. Let's say the example given
above is in a library file called
some_method.rb, then we can do:
require 'reusing' using 'some_method'
The refinement method will find the file, read it in, perform a transformation
class String into
refine String do and wrap it all in a module
which it then passes to the original
using method, which has been aliased, btw,
reusing (hence the name of this library).
Unfortunately the implementation of Reusing is necessarily a bit hackish. Although it works fine for basic extensions scripts there are complications if, for instance, the script requires another extension script. While the scripts extensions will become refinements, the further requirements will not.
Probably the ideal solution would be if refinement syntax could use normal
module keywords, instead of the special
module M class String def important! self + "!" end end end # refinement using M::*
In conjunction with this is should be possible to monkey patch with the same code as well.
# core extension patch M::*
In this way the both techniques could be used via the same code, while still being modular.
Copyright (c) 2014 Rubyworks (BSD-2 License)
See LICENSE.txt for details.