Make CACHE_ROOT a Pathname, this is less surprising.

lib/cocoapods.rb

 require 'rubygems'
 
 module Pod
+  require 'pathname'
+
   require 'cocoapods/gem_version'
   require 'cocoapods-core'
   require 'xcodeproj'
@@ -16,12 +18,12 @@ module Pod
     end
   end
 
-  # @return [String] The directory where CocoaPods caches the downloads.
+  # @return [Pathname] The directory where CocoaPods caches the downloads.
   #
   # @todo   The {Installer::PodSourceInstaller} and the #{ExternalSources}
   #         classes build and configure the downloader from scratch.
   #
-  CACHE_ROOT = "#{ENV['HOME']}/Library/Caches/CocoaPods"
+  CACHE_ROOT = Pathname.new(File.join(ENV['HOME'], 'Library/Caches/CocoaPods'))
 
   # @return [Fixnum] The maximum size for the cache expressed in Mb.
   #
@@ -30,7 +32,7 @@ module Pod
   #
   MAX_CACHE_SIZE = 500
 
-  Pod::Specification::Set::Statistics.instance.cache_file = Pathname.new(CACHE_ROOT) + 'statistics.yml'
+  Pod::Specification::Set::Statistics.instance.cache_file = CACHE_ROOT + 'statistics.yml'
 
   autoload :Command,                'cocoapods/command'
   autoload :Executable,             'cocoapods/executable'
@@ -44,8 +46,6 @@ module Pod
   autoload :UI,                     'cocoapods/user_interface'
   autoload :Validator,              'cocoapods/validator'
 
-  autoload :Pathname,               'pathname'
-
   module Generator
     autoload :Acknowledgements,     'cocoapods/generator/acknowledgements'
     autoload :BridgeSupport,        'cocoapods/generator/bridge_support'

lib/cocoapods/external_sources.rb

@@ -132,7 +132,7 @@ module Pod
           target = sandbox.root + name
           target.rmtree if target.exist?
           downloader = Downloader.for_target(target, params)
-          downloader.cache_root = CACHE_ROOT
+          downloader.cache_root = CACHE_ROOT.to_s
           downloader.max_cache_size = MAX_CACHE_SIZE
           downloader.aggressive_cache = false
           downloader.download

lib/cocoapods/installer/pod_source_installer.rb

@@ -156,7 +156,7 @@ module Pod
       def downloader
         return @downloader if @downloader
         @downloader = Downloader.for_target(root, root_spec.source.dup)
-        @downloader.cache_root = CACHE_ROOT
+        @downloader.cache_root = CACHE_ROOT.to_s
         @downloader.max_cache_size = MAX_CACHE_SIZE
         @downloader.aggressive_cache = aggressive_cache?
         @downloader

lib/cocoapods/sources_manager.rb

@@ -107,8 +107,7 @@ module Pod
       # @return [Pathname] The path where the search index should be stored.
       #
       def search_index_path
-        caches_path = Pathname.new(File.expand_path(CACHE_ROOT))
-        caches_path + 'search_index.yaml'
+        CACHE_ROOT + 'search_index.yaml'
       end
 
       public