Re: Design Question - multiple XML parsers/ dependencies

Am 31. März 2019 um 14:31 Uhr +0800 schrieb Mohit Sindhwani:
> How should we organise such code? Would it basically be two internal
> implementations selected based on a parameter, or detection of the
> installation? Just want to get some ideas or a link to a best practice or
> somehing similar.

If #require fails, it raises a LoadError exception, which can be
rescued. This gives you the neccessary information for loading the
correct parts of your library without having to ask the user:

    begin
      require "ox"
      # ox is available
    rescue LoadError
      # ox is not available
    end

If you keep your library modular, you could then just load the correct
variant:

    begin
      require "ox"
      require_relative "your-library-with/ox"
    rescue LoadError
      require_relative "your-library-with/rexml"
    end

Gerald's suggestion with using a meta library that abstracts the actual
XML library in use is similar to this.

Alternatively, you could set some global piece of information using a
private API, e.g.

    begin
      require "ox"
      YourLibrary.ox_is_available = true
    rescue LoadError
      YourLibrary.ox_is_available = false
    end

-- 
Blog: https://mg.guelker.eu

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