Made command sets take dependencies in account

lib/pry.rb

@@ -19,8 +19,8 @@ end
 require "pry/version"
 require "pry/hooks"
 require "pry/print"
+require "pry/command_base" # to be removed
 require "pry/command_set"
-require "pry/command_base" # to be romved
 require "pry/commands"
 require "pry/command_context"
 require "pry/prompts"

lib/pry/command_set.rb

@@ -10,11 +10,17 @@ class Pry
   class CommandSet
     class Command < Struct.new(:name, :description, :options, :block)
       def call(context, *args)
-        ret = context.instance_exec(*args, &block)
-        ret if options[:keep_retval]
+        if stub_block = options[:stub_info]
+          context.instance_eval(&stub_block)
+        else
+          ret = context.instance_exec(*args, &block)
+          ret if options[:keep_retval]
+        end
       end
     end
 
+    include Pry::CommandBase::CommandBaseHelpers
+
     attr_reader :commands
     attr_reader :name
 
@@ -45,7 +51,7 @@ class Pry
     #   parameters passed into the block will be strings. Successive
     #   command parameters are separated by whitespace at the Pry prompt.
     # @example
-    #   MyCommands Pry::CommandSet.new :mine do
+    #   MyCommands = Pry::CommandSet.new :mine do
     #     command "greet", "Greet somebody" do |name|
     #       puts "Good afternoon #{name.capitalize}!"
     #     end
@@ -58,6 +64,21 @@ class Pry
     #   # pry(main)> help greet
     #   # Greet somebody
     def command(names, description="No description.", options={}, &block)
+      first_name = Array(names).first
+
+      options = {:requires_gem => []}.merge(options)
+
+      unless command_dependencies_met? options
+        gems_needed = Array(options[:requires_gem])
+        gems_not_installed = gems_needed.select { |g| !gem_installed?(g) }
+
+        options[:stub_info] = proc do
+          output.puts "\n#{first_name} requires the following gems to be installed: #{(gems_needed.join(", "))}"
+          output.puts "Command not available due to dependency on gems: `#{gems_not_installed.join(", ")}` not being met."
+          output.puts "Type `install #{first_name}` to install the required gems and activate this command."
+        end
+      end
+
       Array(names).each do |name|
         commands[name] = Command.new(name, description, options, block)
       end
@@ -141,6 +162,37 @@ class Pry
           end
         end
       end
+
+      command "install", "Install a disabled command." do |name|
+        stub_info = commands[name].options[:stub_info]
+
+        if !stub_info
+          output.puts "Not a command stub. Nothing to do."
+          next
+        end
+
+        output.puts "Attempting to install `#{name}` command..."
+        gems_to_install = Array(commands[name].options[:requires_gem])
+
+        gem_install_failed = false
+        gems_to_install.each do |g|
+          next if gem_installed?(g)
+          output.puts "Installing `#{g}` gem..."
+
+          begin
+            Gem::DependencyInstaller.new.install(g)
+          rescue Gem::GemNotFoundException
+            output.puts "Required Gem: `#{g}` not found. Aborting command installation."
+            gem_install_failed = true
+            next
+          end
+        end
+        next if gem_install_failed
+
+        Gem.refresh
+        commands[name].options.delete :stub_info
+        output.puts "Installation of `#{name}` successful! Type `help #{name}` for information"
+      end
     end
   end
 end