Fix up extract command

- Move from cmd to dev-cmd
- Add --stdout flag
- Add sanity checks for args/flags
- Minor rewording on error messages

Library/Homebrew/cmd/extract.rb

@@ -1,53 +0,0 @@
-#:  * `extract` <formula> <version> <tap>:
-#:    Looks through repository history to find the <version> of <formula> and
-#:    creates a copy in <tap>/Formula/<formula>@<version>.rb. If the tap is
-#:    not installed yet, attempts to install/clone the tap before continuing.
-#:
-#:    If the file at <tap>/Formula/<formula>@<version>.rb already exists,
-#:    it will not be overwritten unless `--force` is specified.
-#:
-
-require "utils/git"
-require "formula_versions"
-require "formulary"
-require "tap"
-
-module Homebrew
-  module_function
-
-  def extract
-    formula = Formulary.factory(ARGV.named[0])
-    version = ARGV.named[1]
-    dest = Tap.fetch(ARGV.named[2])
-    dest.install unless dest.installed?
-    path = Pathname.new("#{dest.path}/Formula/#{formula}@#{version}.rb")
-    if path.exist?
-      unless ARGV.force?
-        odie <<~EOS
-          Destination formula already exists: #{path}
-          To overwrite it and continue anyways, run `brew extract #{formula} #{version} #{dest.name} --force`.
-        EOS
-      end
-      ohai "Clobbering existing formula at #{path}" if ARGV.debug?
-      path.delete
-    end
-
-    rev = "HEAD"
-    version_resolver = FormulaVersions.new(formula)
-    rev = Git.last_revision_commit_of_file(formula.path.parent.parent, formula.path, before_commit: "#{rev}~1") until version_resolver.formula_at_revision(rev) { |f| version_matches?(f, version, rev) || rev.empty? }
-
-    odie "Could not find #{formula} #{version}." if rev.empty?
-
-    result = version_resolver.file_contents_at_revision(rev)
-    ohai "Writing formula for #{formula} from #{rev} to #{path}"
-
-    # The class name has to be renamed to match the new filename, e.g. Foo version 1.2.3 becomes FooAT123 and resides in Foo@1.2.3.rb.
-    path.write result.gsub("class #{formula.name.capitalize} < Formula", "class #{formula.name.capitalize}AT#{version.gsub(/[^0-9a-z ]/i, "")} < Formula")
-  end
-
-  # @private
-  def version_matches?(formula, version, rev)
-    ohai "Trying #{formula.version} from revision #{rev} against desired #{version}" if ARGV.debug?
-    formula.version == version
-  end
-end

Library/Homebrew/dev-cmd/extract.rb

@@ -0,0 +1,75 @@
+#:  * `extract` [`--force`] [`--stdout`] <formula> <version> [<tap>]:
+#:    Looks through repository history to find the <version> of <formula> and
+#:    creates a copy in <tap>/Formula/<formula>@<version>.rb. If the tap is
+#:    not installed yet, attempts to install/clone the tap before continuing.
+#:
+#:    If `--force` is passed, the file at the destination will be overwritten
+#:    if it already exists. Otherwise, existing files will be preserved.
+#:
+#:    If `--stdout` is passed, the file will be written to stdout on the
+#:    terminal instead of written to a file. A <tap> cannot be passed when
+#:    using `--stdout`.
+
+require "utils/git"
+require "formula_versions"
+require "formulary"
+require "tap"
+
+module Homebrew
+  module_function
+
+  def extract
+  	Homebrew::CLI::Parser.parse do
+      switch      "--stdout", description: "Output to stdout on terminal instead of file"
+      switch      :debug
+      switch      :force
+	  end
+
+    odie "Cannot use a tap and --stdout at the same time!" if ARGV.named.length == 3 && args.stdout?
+    raise UsageError unless (ARGV.named.length == 3 && !args.stdout?) || (ARGV.named.length == 2 && args.stdout?)
+
+    formula = Formulary.factory(ARGV.named.first)
+    version = ARGV.named[1]
+    destination_tap = Tap.fetch(ARGV.named[2]) unless args.stdout?
+    destination_tap.install unless destination_tap.installed? unless args.stdout?
+
+    unless args.stdout?
+      path = Pathname.new("#{destination_tap.path}/Formula/#{formula}@#{version}.rb")
+      if path.exist?
+        unless ARGV.force?
+          odie <<~EOS
+            Destination formula already exists: #{path}
+            To overwrite it and continue anyways, run `brew extract #{formula} #{version} #{destination_tap.name} --force`.
+          EOS
+        end
+        ohai "Overwriting existing formula at #{path}" if ARGV.debug?
+        path.delete
+      end
+    end
+
+    rev = "HEAD"
+    version_resolver = FormulaVersions.new(formula)
+    until version_resolver.formula_at_revision(rev) { |f| version_matches?(f, version, rev) || rev.empty? } do
+      rev = Git.last_revision_commit_of_file(formula.path.parent.parent, formula.path, before_commit: "#{rev}~1")
+    end
+
+    odie "Could not find #{formula} #{version}!" if rev.empty?
+
+    result = version_resolver.file_contents_at_revision(rev)
+
+    # The class name has to be renamed to match the new filename, e.g. Foo version 1.2.3 becomes FooAT123 and resides in Foo@1.2.3.rb.
+    result.gsub!("class #{formula.name.capitalize} < Formula", "class #{formula.name.capitalize}AT#{version.gsub(/[^0-9a-z ]/i, "")} < Formula")
+    if args.stdout?
+      puts result if args.stdout?
+    else
+      ohai "Writing formula for #{formula} from #{rev} to #{path}"
+      path.write result
+    end
+  end
+
+  # @private
+  def version_matches?(formula, version, rev)
+    ohai "Trying #{formula.version} from revision #{rev} against desired #{version}" if ARGV.debug?
+    formula.version == version
+  end
+end