Relax polisher dependencies, gracefully fail if deps are missing

Now polisher gem contains minimal runtime deps w/ mechanism
to catch runtime load errors. Components missing reqs will
not be accessible / calling methods on them will indicate
to install optional dependencies

bin/git_gem_updater.rb

@@ -11,10 +11,7 @@
 # Copyright (C) 2013-2014 Red Hat, Inc.
 
 require 'colored'
-require 'curb'
-require 'json'
 require 'optparse'
-require 'nokogiri'
 
 require 'polisher/git'
 require 'polisher/gem'

lib/polisher/errata.rb

@@ -3,9 +3,19 @@
 # Licensed under the MIT license
 # Copyright (C) 2013-2014 Red Hat, Inc.
 
+skip_module = false
+begin
 require 'json'
 require 'curb'
+rescue LoadError
+  skip_module = true
+end
+
+if skip_module
+require 'polisher/missing'
+Polisher::Errata = Polisher::MissingComponent
 
+else
 require 'polisher/core'
 
 module Polisher
@@ -73,3 +83,4 @@ def self.build_version(build, name)
     end
   end
 end
+end # (!skip_module)

lib/polisher/fedora.rb

@@ -3,9 +3,20 @@
 # Licensed under the MIT license
 # Copyright (C) 2013-2014 Red Hat, Inc.
 
+skip_module = false
+begin
 require 'curb'
 require 'pkgwat'
+require 'nokogiri'
+rescue LoadError
+  skip_module = true
+end
 
+if skip_module
+require 'polisher/missing'
+Polisher::Fedora = Polisher::MissingComponent
+
+else
 require 'polisher/bodhi'
 
 module Polisher
@@ -44,3 +55,4 @@ def self.versions_for(name, &bl)
     end
   end # class Fedora
 end # module Polisher
+end # (!skip_module)

lib/polisher/gem.rb

@@ -3,6 +3,8 @@
 # Licensed under the MIT license
 # Copyright (C) 2013-2014 Red Hat, Inc.
 
+skip_module = false
+begin
 require 'curb'
 require 'json'
 require 'yaml'
@@ -12,7 +14,15 @@
 require 'awesome_spawn'
 require 'rubygems/installer'
 require 'active_support/core_ext'
+rescue LoadError
+  skip_module = true
+end
 
+if skip_module
+require 'polisher/missing'
+Polisher::Gem = Polisher::MissingComponent
+
+else
 require 'polisher/version_checker'
 require 'polisher/gem_cache'
 require 'polisher/vendor'
@@ -310,3 +320,4 @@ def diff(other)
 
   end # class Gem
 end # module Polisher
+end # (!skip_module)

lib/polisher/gemfile.rb

@@ -3,8 +3,18 @@
 # Licensed under the MIT license
 # Copyright (C) 2013-2014 Red Hat, Inc.
 
+skip_module = false
+begin
 require 'bundler'
+rescue LoadError
+  skip_module = true
+end
 
+if skip_module
+require 'polisher/missing'
+Polisher::Gemfil = Polisher::MissingComponent
+
+else
 require 'polisher/git'
 require 'polisher/gem'
 require 'polisher/version_checker'
@@ -96,3 +106,4 @@ def patched
     end
   end # class Gemfile
 end # module Polisher
+end # (!skip_module)

lib/polisher/git/pkg.rb

@@ -3,15 +3,25 @@
 # Licensed under the MIT license
 # Copyright (C) 2013-2014 Red Hat, Inc.
 
+skip_module = false
+begin
 require 'awesome_spawn'
+rescue LoadError
+  skip_module = true
+end
 
+if skip_module
+require 'polisher/missing'
+Polisher::Git::Pkg = Polisher::MissingComponent
+
+else
 require 'polisher/error'
 require 'polisher/git/repo'
 require 'polisher/rpm/spec'
 
 module Polisher
   module Git
-    # Git Repository
+    # Git Based Package
     class Pkg < Repo
       attr_accessor :name
       attr_accessor :version
@@ -189,3 +199,4 @@ def self.version_for(name, &bl)
     end # module Pkg
   end # module Git
 end # module Polisher
+end # (!skip_module)

lib/polisher/git/repo.rb

@@ -3,7 +3,19 @@
 # Licensed under the MIT license
 # Copyright (C) 2013-2014 Red Hat, Inc.
 
+skip_module = false
+begin
 require 'awesome_spawn'
+
+rescue LoadError
+  skip_module = true
+end
+
+if skip_module
+require 'polisher/missing'
+Polisher::Git::Repo = Polisher::MissingComponent
+
+else
 require 'polisher/core'
 require 'polisher/git_cache'
 
@@ -72,3 +84,4 @@ def commit(msg)
     end # class Repo
   end # module Git
 end # module Polisher
+end # (!skip_module)

lib/polisher/koji.rb

@@ -3,8 +3,19 @@
 # Licensed under the MIT license
 # Copyright (C) 2013-2014 Red Hat, Inc.
 
+skip_module = false
+begin
 require 'xmlrpc/client'
 require 'active_support/core_ext/kernel/reporting'
+rescue LoadError
+  skip_module = true
+end
+
+if skip_module
+require 'polisher/missing'
+Polisher::Koji = Polisher::MissingComponent
+
+else
 silence_warnings do
   XMLRPC::Config::ENABLE_NIL_PARSER = true
   XMLRPC::Config::ENABLE_NIL_CREATE = true
@@ -104,3 +115,4 @@ def self.diff(tag1, tag2)
     end
   end
 end
+end # (!skip_module)

lib/polisher/missing.rb

@@ -0,0 +1,12 @@
+# Polisher "Missing" Component
+#
+# Licensed under the MIT license
+# Copyright (C) 2014 Red Hat, Inc.
+
+module Polisher
+  class MissingComponent
+    def method_missing(method_id, *args, &bl)
+      raise "polisher is missing a dependency - cannot invoke #{method_id} on #{self}"
+    end
+  end # class MissingComponent
+end # module Polisher

lib/polisher/rpm/requirement.rb

@@ -3,10 +3,20 @@
 # Licensed under the MIT license
 # Copyright (C) 2013-2014 Red Hat, Inc.
 
+skip_module = false
+begin
 require 'gem2rpm'
 require 'versionomy'
 require 'active_support/core_ext'
+rescue LoadError
+  skip_module = true
+end
+
+if skip_module
+require 'polisher/missing'
+Polisher::RPM::Requirement = Polisher::MissingComponent
 
+else
 require 'polisher/core'
 require 'polisher/gem'
 
@@ -186,3 +196,4 @@ def gem_name
     end # class Requirement
   end # module RPM 
 end
+end # (!skip_module)

lib/polisher/rpm/spec.rb

@@ -3,10 +3,20 @@
 # Licensed under the MIT license
 # Copyright (C) 2013-2014 Red Hat, Inc.
 
+skip_module = false
+begin
 require 'gem2rpm'
 require 'versionomy'
 require 'active_support/core_ext'
+rescue LoadError
+  skip_module = true
+end
 
+if skip_module
+require 'polisher/missing'
+Polisher::RPM::Spec = Polisher::MissingComponent
+
+else
 require 'polisher/core'
 require 'polisher/gem'
 require 'polisher/rpm/requirement'
@@ -379,3 +389,4 @@ def compare(upstream_source)
     end # class Spec
   end # module RPM
 end # module Polisher
+end # (!skip_module)

lib/polisher/yum.rb

@@ -3,8 +3,18 @@
 # Licensed under the MIT license
 # Copyright (C) 2013-2014 Red Hat, Inc.
 
+skip_module = false
+begin
 require 'awesome_spawn'
+rescue LoadError
+  skip_module = true
+end
+
+if skip_module
+require 'polisher/missing'
+Polisher::Yum = Polisher::MissingComponent
 
+else
 module Polisher
   class Yum
     YUM_CMD = '/usr/bin/yum'
@@ -28,3 +38,4 @@ def self.version_for(name, &bl)
     end
   end
 end
+end # (!skip_module)

polisher.gemspec

@@ -28,17 +28,16 @@ Gem::Specification.new do |s|
                      'git_gem_updater.rb', 'ruby_rpm_spec_updater.rb']
   s.require_paths = ['lib']
 
-  # TODO tighten up deps, some may be optional
-  s.add_dependency('json')
-  s.add_dependency('curb')
-  s.add_dependency('activesupport')
-  s.add_dependency('i18n')
-  s.add_dependency('bundler')
-  s.add_dependency('pkgwat')
   s.add_dependency('colored')
-  s.add_dependency('awesome_spawn')
-  s.add_dependency('gem2rpm')
-  s.add_dependency('versionomy')
   s.add_development_dependency('rspec', '>= 2.0.0')
   s.add_development_dependency('coveralls')
+  s.add_development_dependency('json')
+  s.add_development_dependency('curb')
+  s.add_development_dependency('activesupport')
+  s.add_development_dependency('i18n')
+  s.add_development_dependency('bundler')
+  s.add_development_dependency('pkgwat')
+  s.add_development_dependency('awesome_spawn')
+  s.add_development_dependency('gem2rpm')
+  s.add_development_dependency('versionomy')
 end