document Tap class

Closes Homebrew/homebrew#40608.

Signed-off-by: Xu Cheng <xucheng@me.com>

Library/Homebrew/tap.rb

@@ -1,11 +1,29 @@
+# a {Tap} is used to extend the formulae provided by Homebrew core.
+# Usually, it's synced with a remote git repository. And it's likely
+# a Github repository with the name of `user/homebrew-repo`. In such
+# case, `user/repo` will be used as the {#name} of this {Tap}, where
+# {#user} represents Github username and {#repo} represents repository
+# name without leading `homebrew-`.
+# @abstract
 class Tap
   TAP_DIRECTORY = HOMEBREW_LIBRARY/"Taps"
 
   extend Enumerable
 
+  # The user name of this {Tap}. Usually, it's the Github username of
+  # this #{Tap}'s remote repository.
   attr_reader :user
+
+  # The repository name of this {Tap} without leading `homebrew-`.
   attr_reader :repo
+
+  # The name of this {Tap}. It combines {#user} and {#repo} with a slash.
+  # {#name} is always in lowercase.
+  # e.g. `user/repo`
   attr_reader :name
+
+  # The local path to this {Tap}.
+  # e.g. `/usr/local/Library/Taps/user/homebrew-repo`
   attr_reader :path
 
   def initialize(user, repo)
@@ -16,6 +34,8 @@ class Tap
     @path = TAP_DIRECTORY/"#{@user}/homebrew-#{@repo}".downcase
   end
 
+  # The remote path to this {Tap}.
+  # e.g. `https://github.com/user/homebrew-repo`
   def remote
     @remote ||= if installed?
       if (@path/".git").exist?
@@ -34,10 +54,12 @@ class Tap
     name
   end
 
+  # True if this {Tap} is an official Homebrew tap.
   def official?
     @user == "Homebrew"
   end
 
+  # True if the remote of this {Tap} is a private repository.
   def private?
     return true if custom_remote?
     GitHub.private_repo?(@user, "homebrew-#{@repo}")
@@ -47,25 +69,30 @@ class Tap
     false
   end
 
+  # True if this {Tap} has been installed.
   def installed?
     @path.directory?
   end
 
+  # True if the {#remote} of {Tap} is customized.
   def custom_remote?
     return true unless remote
     remote.casecmp("https://github.com/#{@user}/homebrew-#{@repo}") != 0
   end
 
+  # an array of all {Formula} files of this {Tap}.
   def formula_files
     dir = [@path/"Formula", @path/"HomebrewFormula", @path].detect(&:directory?)
     return [] unless dir
     dir.children.select { |p| p.extname == ".rb" }
   end
 
+  # an array of all {Formula} names of this {Tap}.
   def formula_names
     formula_files.map { |f| "#{name}/#{f.basename(".rb")}" }
   end
 
+  # an array of all commands files of this {Tap}.
   def command_files
     Pathname.glob("#{path}/cmd/brew-*").select(&:executable?)
   end
@@ -98,6 +125,7 @@ class Tap
     end
   end
 
+  # an array of all installed {Tap} names.
   def self.names
     map(&:name)
   end