Drop hard dependency on RDoc.

[voxik]

This has been introduced in 0267004, but it seems that this is just be mistake, otherwise the later handling of LoadError would not be needed.

Of course I might misunderstand the code. But if that is the case, I still think that RDoc should not be loaded by default during startup, but later when really needed.

[hsbt]

👍 Nice catch. I agree to remove the top of require "rdoc".

[junaruga]

I think this PR's change is wrong, because there is no logic for begin .. require 'rdoc' .. rescue LoadError .. end any more on the "latest master"'s. input-method.rb. The logic was deleted by 5f749c6 .
And this file is using RDoc.

$ grep -ri rdoc lib/irb/input-method.rb
      driver = RDoc::RI::Driver.new(options)
        rescue RDoc::RI::Driver::NotFoundError
      rescue RDoc::RI::Driver::NotFoundError
        doc = RDoc::Markup::Document.new
        rescue RDoc::RI::Driver::NotFoundError
      formatter = RDoc::Markup::ToAnsi.new

[junaruga]

Searching parts requiring rdoc, there are 4 files requiring it.

$ grep -ri rdoc lib/
lib/irb/cmd/help.rb:        require 'rdoc/ri/driver'
lib/irb/cmd/help.rb:        opts = RDoc::RI::Driver.process_args([])
lib/irb/cmd/help.rb:        IRB::ExtendCommand::Help.const_set(:Ri, RDoc::RI::Driver.new(opts))
lib/irb/cmd/help.rb:            rescue RDoc::RI::Error
lib/irb/completion.rb:        require 'rdoc'
lib/irb/completion.rb:      RDocRIDriver ||= RDoc::RI::Driver.new
lib/irb/completion.rb:        out = RDoc::Markup::Document.new
lib/irb/completion.rb:            RDocRIDriver.add_method(out, m)  
lib/irb/completion.rb:          rescue RDoc::RI::Driver::NotFoundError
lib/irb/completion.rb:        RDocRIDriver.display(out)
lib/irb/completion.rb:          RDocRIDriver.display_names([namespace])
lib/irb/completion.rb:        rescue RDoc::RI::Driver::NotFoundError
lib/irb/easter-egg.rb:          require "rdoc"
lib/irb/easter-egg.rb:          RDoc::RI::Driver.new.page do |io|
lib/irb/input-method.rb:      driver = RDoc::RI::Driver.new(options)
lib/irb/input-method.rb:        rescue RDoc::RI::Driver::NotFoundError
lib/irb/input-method.rb:      rescue RDoc::RI::Driver::NotFoundError
lib/irb/input-method.rb:        doc = RDoc::Markup::Document.new
lib/irb/input-method.rb:        rescue RDoc::RI::Driver::NotFoundError
lib/irb/input-method.rb:      formatter = RDoc::Markup::ToAnsi.new

And in lib/irb/cmd/help.rb, lib/irb/completion.rb and lib/irb/easter-egg.rb, the require "rdoc" or require 'rdoc/ri/driver' are executed in a small scope handling the error by rescue LoadError. So, I think the 5f749c6 might be mistake. And this PR's commit is ok.

[voxik]

Oh, wow, where I left my eyes? 🙈 Maybe I got confused by the commit I have referenced without checking further? Sorry.

But still, I'd love to see the hard dependency removed.