Add brew pull for easy integration of user patches

Library/Contributions/examples/brew-pull.rb

@@ -0,0 +1,49 @@
+# Gets a patch from a GitHub commit or pull request and applies it to Homebrew.
+# Optionally, installs it too.
+
+require 'utils.rb'
+
+if ARGV.empty?
+  puts 'This command requires at least one URL argument'
+  exit 1
+end
+
+if ARGV.include? '--install'
+  ARGV.delete '--install'
+  install = true
+end
+
+HOMEBREW_REPOSITORY.cd do
+  ARGV.each do|arg|
+    # This regex should work, if it's too precise, feel free to fix it.
+    if !arg.match 'https:\/\/github.com\/\w+\/homebrew\/(pull\/\d+|commit\/\w{40})'
+      ohai 'Ignoring URL:', "Not a GitHub pull request or commit: #{arg}"
+      next
+    end
+    
+    # GitHub provides commits'/pull-requests' raw patches using this URL.
+    url = arg + '.patch'
+    
+    # The cache directory seems like a good place to put patches.
+    patchpath = (HOMEBREW_CACHE+File.basename(url))
+    curl url, '-o', patchpath
+    
+    # Makes sense to squash whitespace errors, we don't want them.
+    ohai 'Applying patch'
+    safe_system 'git', 'am', '--signoff', '--whitespace=fix', patchpath
+    
+    ohai 'Patch changed:'
+    safe_system 'git', 'diff', 'HEAD~1', '--stat'
+    
+    if install
+      status, filename = `git diff HEAD~1 --name-status`.split()
+      # Don't try and do anything to removed files.
+      if status == 'A' or status == 'M'
+        formula = File.basename(filename, '.rb')
+        ohai "Installing #{formula}"
+        # Not sure if this is the best way to install?
+        safe_system 'brew', 'install', '--force', formula
+      end
+    end
+  end
+end