Use rubygems-requirements-system to install system dependencies automatically

It's a successor product of native-package-installer.

See also:
* https://github.com/ruby-gnome/rubygems-requirements-system/
* https://github.com/ruby-gnome/native-package-installer

It uses `requirements` in gemspec instead of installing system
dependencies manually that is used approach by
native-package-installer.

It uses opt-in style. So users need to enable it explicitly by `gem
install rubygems-requirements-system` or `plugin
"rubygems-requirements-system"` in `Gemfile`.

Author: kou

.github/workflows/ci.yml

@@ -70,7 +70,7 @@ jobs:
 
       - name: Install IRuby gem
         run: |
-          sudo apt update # Preparation for Native Package Installer
+          gem install rubygems-requirements-system
           gem install pkg/*.gem
 
       - run: ruby -r iruby -e "p IRuby::SessionAdapter.select_adapter_class"

Gemfile

@@ -1,4 +1,7 @@
 source 'https://rubygems.org'
+
+plugin 'rubygems-requirements-system'
+
 gemspec
 
 group :pry do

README.md

@@ -40,34 +40,24 @@ See the official document to know how to install Jupyter Notebook and/or Jupyter
 
 ### Ubuntu
 
-#### Ubuntu 17+
+#### Ubuntu 22.04+
 
 ```shell
 sudo apt install libtool libffi-dev ruby ruby-dev make
 
-gem install --user-install iruby
-iruby register --force
-```
-
-#### Ubuntu 16
-
-The latest IRuby requires Ruby >= 2.4 while Ubuntu's official Ruby package is version 2.3.
-So you need to install Ruby >= 2.4 by yourself before preparing IRuby.
-We recommend to use rbenv.
-
-```shell
-sudo apt install libtool libffi-dev ruby ruby-dev make
+gem install --user-install rubygems-requirements-system
 gem install --user-install iruby
 iruby register --force
 ```
 
 ### Fedora
 
-#### Fedora 36
+#### Fedora 40+
 
 ```shell
 sudo dnf install ruby ruby-dev make zeromq-devel
 
+gem install --user-install rubygems-requirements-system
 gem install --user-install iruby
 iruby register --force
 ```
@@ -89,6 +79,7 @@ Install Jupyter.
 #### Homebrew
 
 ```shell
+gem install rubygems-requirements-system
 gem install iruby
 iruby register --force
 ```
@@ -99,6 +90,7 @@ If you are using macports, run the following commands.
 
 ```shell
 port install libtool autoconf automake autogen
+gem install rubygems-requirements-system
 gem install iruby
 iruby register --force
 ```

ext/Rakefile

@@ -15,7 +15,6 @@ Gem::Specification.new do |s|
   s.executables   = %w[iruby]
   s.test_files    = s.files.grep(%r{^test/})
   s.require_paths = %w[lib]
-  s.extensions    = %w[ext/Rakefile]
 
   s.required_ruby_version = '>= 2.3.0'
 
@@ -25,12 +24,21 @@ Gem::Specification.new do |s|
   s.add_dependency 'logger'
   s.add_dependency 'mime-types', '>= 3.3.1'
   s.add_dependency 'multi_json', '~> 1.11'
-  s.add_dependency 'native-package-installer'
 
   s.add_development_dependency 'pycall', '>= 1.2.1'
   s.add_development_dependency 'rake'
   s.add_development_dependency 'test-unit'
   s.add_development_dependency 'test-unit-rr'
 
+  [
+    ['arch_linux', 'zeromq'],
+    ['debian', 'libzmq3-dev'],
+    ['freebsd', 'libzmq4'],
+    ['homebrew', 'zmq'],
+    ['macports', 'zmq'],
+  ].each do |platform, package|
+    s.requirements << "system: libzmq: #{platform}: #{package}"
+  end
+
   s.metadata['msys2_mingw_dependencies'] = 'zeromq'
 end