Unexpect overriding standard `Set` class about egison-ruby

[egisatoshi]

Thank you for your information.

I've updated the code to add methods to existing ::Set provided by the standard library.

https://github.com/egison/egison-ruby/blob/v0.2.1/lib/egison/matcher.rb

How do you think about it?
By the way, the name of gem is "egison", not "edison".

[mirakui]

Sorry for typo 🙇

IMO, gems should not extend existing standard classes as possible except special cases.
For example, I think everyone who uses activesupport knows that activesupport extends lots of existing Ruby classes.
But people who want to do the cool pattern matching using egison-ruby may not expect that egison-ruby extends Ruby's Set.

[egisatoshi]

I don't want to type ::Egison::Set for each pattern matching is not cool though I' also don't want to extend Ruby's Set.
Are there good ways to solve this problem?

[mirakui]

I think one of ruby-ish way is:

require 'egison'

include Egison # <- Import methods of Egison module into the namespace

match_all([1, 2, 3]) do  # <- should be Egision.match_all instead of Kernel.match_all
  with(Set.(_a, _b, *_)) do # <- Set means Egison::Set
    [a, b]
  end
end

In this way, you can simply write Set to use ::Egison::Set.

[sorah]

as @mirakui said, user expects egison to do pattern matching, but not expects to extend ::Set.
Cons of extending existing classes is when other library or user is extending same class with same method name, it'll be a strange bug due to conflict. Hard to investigate.

I recommend to not extend existing classes if you don't have proper reason to extend.

using module_eval(Egison) to inject namespace in Egison.match_all implementation is better?

[egisatoshi]

@mirakui @sorah Thank you so much for your advice!
I think your approach is great and I'd like to try with your approach.

However, the problem is I'm not familiar enough to Ruby to update the code at once.
If it is not hard for you to refine code, would you help me?

[egisatoshi]

@mirakui @sorah I deepened my knowledge on Ruby and think I've solved this issue. Please check it if you have a chance.