Remove unnecessary classes / modules used by config (#1897)

* Remove` Pry::Config::Default`

* Remove `Pry::Config::Memoization`

* Remove confusing use of `instance_eval`

* Add `Pry::Config.defaults`
  Returns an instance of `Pry::Config`, initialized with Pry defaults.
  Replaces the previous role of `Pry::Config::Default`.

9 files changed, 90 insertions, 226 deletions

diff --git a/lib/pry.rb b/lib/pry.rb
index 14f20e44..7414220a 100644
--- a/lib/pry.rb
+++ b/lib/pry.rb
@@ -114,8 +114,6 @@ require 'pry/basic_object'
 require "pry/prompt"
 require 'pry/config/lazy'
 require 'pry/config/behavior'
-require 'pry/config/memoization'
-require 'pry/config/default'
 require 'pry/config/convenience'
 require 'pry/config'
 require 'pry/pry_class'
diff --git a/lib/pry/basic_object.rb b/lib/pry/basic_object.rb
index fa2dccfb..ab4b03e2 100644
--- a/lib/pry/basic_object.rb
+++ b/lib/pry/basic_object.rb
@@ -1,5 +1,5 @@
 class Pry::BasicObject < BasicObject
-  [:Kernel, :Pry].each do |constant|
+  [:Kernel, :File, :Dir, :LoadError, :ENV, :Pry].each do |constant|
     const_set constant, ::Object.const_get(constant)
   end
   include Kernel
diff --git a/lib/pry/config.rb b/lib/pry/config.rb
index 1cd12f5b..5b0dd9b8 100644
--- a/lib/pry/config.rb
+++ b/lib/pry/config.rb
@@ -4,8 +4,87 @@ class Pry
   class Config < Pry::BasicObject
     include Behavior
 
+    #
+    # @return [Pry::Config]
+    #   An object who implements the default configuration for all
+    #   Pry sessions.
+    #
+    def self.defaults
+      defaults = from_hash(
+        input: Pry.lazy { lazy_readline(defaults) },
+        output: $stdout.tap { |out| out.sync = true },
+        commands: Pry::Commands,
+        prompt_name: Pry::Prompt::DEFAULT_NAME,
+        prompt: Pry::Prompt[:default],
+        prompt_safe_contexts: Pry::Prompt::SAFE_CONTEXTS,
+        print: Pry::DEFAULT_PRINT,
+        quiet: false,
+        exception_handler: Pry::DEFAULT_EXCEPTION_HANDLER,
+        unrescued_exceptions: Pry::DEFAULT_UNRESCUED_EXCEPTIONS,
+        exception_whitelist: Pry.lazy do
+                               defaults.output.puts '[warning] Pry.config.exception_whitelist is deprecated, ' \
+                                                    'please use Pry.config.unrescued_exceptions instead.'
+                               Pry::DEFAULT_UNRESCUED_EXCEPTIONS
+                             end,
+        hooks: Pry::DEFAULT_HOOKS,
+        pager: true,
+        system: Pry::DEFAULT_SYSTEM,
+        color: Pry::Helpers::BaseHelpers.use_ansi_codes?,
+        default_window_size: 5,
+        editor: Pry.default_editor_for_platform,
+        should_load_rc: true,
+        should_load_local_rc: true,
+        should_trap_interrupts: Pry::Helpers::Platform.jruby?,
+        disable_auto_reload: false,
+        command_prefix: "",
+        auto_indent: Pry::Helpers::BaseHelpers.use_ansi_codes?,
+        correct_indent: true,
+        collision_warning: false,
+        output_prefix: "=> ",
+        requires: [],
+        should_load_requires: true,
+        should_load_plugins: true,
+        windows_console_warning: true,
+        control_d_handler: Pry::DEFAULT_CONTROL_D_HANDLER,
+        memory_size: 100,
+        extra_sticky_locals: {},
+        command_completions: Pry.lazy { defaults.commands.keys },
+        file_completions: proc { Dir["."] },
+        ls: Pry::Config.from_hash(Pry::Command::Ls::DEFAULT_OPTIONS),
+        completer: Pry::InputCompleter,
+        gist: Pry::Config.from_hash(inspecter: proc(&:pretty_inspect)),
+        history: Pry::Config.from_hash(should_save: true, should_load: true).tap do |history|
+          history_file = if File.exist?(File.expand_path('~/.pry_history'))
+                           '~/.pry_history'
+                         elsif ENV.key?('XDG_DATA_HOME') && ENV['XDG_DATA_HOME'] != ''
+                           # See XDG Base Directory Specification at
+                           # https://standards.freedesktop.org/basedir-spec/basedir-spec-0.8.html
+                           ENV['XDG_DATA_HOME'] + '/pry/pry_history'
+                         else
+                           '~/.local/share/pry/pry_history'
+                         end
+          history.file = File.expand_path(history_file)
+        end,
+        exec_string: ""
+      )
+    end
+
     def self.shortcuts
       Convenience::SHORTCUTS
     end
+
+    # @api private
+    def self.lazy_readline(defaults)
+      require 'readline'
+      ::Readline
+    rescue LoadError
+      defaults.output.puts "Sorry, you can't use Pry without Readline or a compatible library. \n" \
+                           "Possible solutions: \n" \
+                           " * Rebuild Ruby with Readline support using `--with-readline` \n" \
+                           " * Use the rb-readline gem, which is a pure-Ruby port of Readline \n" \
+                           " * Use the pry-coolline gem, a pure-ruby alternative to Readline"
+      raise
+    end
+    private_class_method :lazy_readline
   end
 end
diff --git a/lib/pry/config/behavior.rb b/lib/pry/config/behavior.rb
index f819ae56..9d6c936a 100644
--- a/lib/pry/config/behavior.rb
+++ b/lib/pry/config/behavior.rb
@@ -273,7 +273,7 @@ class Pry
 
       #
       # @example
-      #   # _pry_.config -> Pry.config -> Pry::Config::Default
+      #   # _pry_.config -> Pry.config -> Pry::Config.defaults
       #   _pry_.config.last_default
       #
       # @return [Pry::Config::Behaviour]
diff --git a/lib/pry/config/default.rb b/lib/pry/config/default.rb
deleted file mode 100644
index 5a2f70f9..00000000
--- a/lib/pry/config/default.rb
+++ /dev/null
@@ -1,162 +0,0 @@
-class Pry
-  class Config < Pry::BasicObject
-    class Default
-      include Config::Behavior
-      include Config::Memoization
-
-      def_memoized({
-        input: proc {
-          lazy_readline
-        },
-        output: proc {
-          $stdout.tap { |out| out.sync = true }
-        },
-        commands: proc {
-          Pry::Commands
-        },
-        prompt_name: proc {
-          Pry::Prompt::DEFAULT_NAME
-        },
-        prompt: proc {
-          Pry::Prompt[:default]
-        },
-        prompt_safe_contexts: proc {
-          Pry::Prompt::SAFE_CONTEXTS
-        },
-        print: proc {
-          Pry::DEFAULT_PRINT
-        },
-        quiet: proc {
-          false
-        },
-        exception_handler: proc {
-          Pry::DEFAULT_EXCEPTION_HANDLER
-        },
-        unrescued_exceptions: proc {
-          Pry::DEFAULT_UNRESCUED_EXCEPTIONS
-        },
-        exception_whitelist: proc {
-          warn 'Pry.config.exception_whitelist is deprecated, please use Pry.config.unrescued_exceptions instead.'
-          Pry::DEFAULT_UNRESCUED_EXCEPTIONS
-        },
-        hooks: proc {
-          Pry::DEFAULT_HOOKS
-        },
-        pager: proc {
-          true
-        },
-        system: proc {
-          Pry::DEFAULT_SYSTEM
-        },
-        color: proc {
-          Pry::Helpers::BaseHelpers.use_ansi_codes?
-        },
-        default_window_size: proc {
-          5
-        },
-        editor: proc {
-          Pry.default_editor_for_platform
-        },
-        should_load_rc: proc {
-          true
-        },
-        should_load_local_rc: proc {
-          true
-        },
-        should_trap_interrupts: proc {
-          Pry::Helpers::Platform.jruby?
-        },
-        disable_auto_reload: proc {
-          false
-        },
-        command_prefix: proc {
-          ""
-        },
-        auto_indent: proc {
-          Pry::Helpers::BaseHelpers.use_ansi_codes?
-        },
-        correct_indent: proc {
-          true
-        },
-        collision_warning: proc {
-          false
-        },
-        output_prefix: proc {
-          "=> "
-        },
-        requires: proc {
-          []
-        },
-        should_load_requires: proc {
-          true
-        },
-        should_load_plugins: proc {
-          true
-        },
-        windows_console_warning: proc {
-          true
-        },
-        control_d_handler: proc {
-          Pry::DEFAULT_CONTROL_D_HANDLER
-        },
-        memory_size: proc {
-          100
-        },
-        extra_sticky_locals: proc {
-          {}
-        },
-        command_completions: proc {
-          proc { commands.keys }
-        },
-        file_completions: proc {
-          proc { Dir["."] }
-        },
-        ls: proc {
-          Pry::Config.from_hash(Pry::Command::Ls::DEFAULT_OPTIONS)
-        },
-        completer: proc {
-          Pry::InputCompleter
-        },
-        gist: proc {
-          Pry::Config.from_hash({inspecter: proc(&:pretty_inspect)})
-        },
-        history: proc {
-          Pry::Config.from_hash({should_save: true, should_load: true}).tap do |history|
-            history_file =
-              if File.exist?(File.expand_path('~/.pry_history'))
-                '~/.pry_history'
-              elsif ENV.key?('XDG_DATA_HOME') && ENV['XDG_DATA_HOME'] != ''
-                # See XDG Base Directory Specification at
-                # https://standards.freedesktop.org/basedir-spec/basedir-spec-0.8.html
-                ENV['XDG_DATA_HOME'] + '/pry/pry_history'
-              else
-                '~/.local/share/pry/pry_history'
-              end
-            history.file = File.expand_path(history_file)
-          end
-        },
-        exec_string: proc {
-          ""
-        }
-      })
-
-      def initialize
-        super(nil)
-      end
-
-      private
-
-      def lazy_readline
-        require 'readline'
-        Readline
-      rescue LoadError
-        warn "Sorry, you can't use Pry without Readline or a compatible library."
-        warn "Possible solutions:"
-        warn " * Rebuild Ruby with Readline support using `--with-readline`"
-        warn " * Use the rb-readline gem, which is a pure-Ruby port of Readline"
-        warn " * Use the pry-coolline gem, a pure-ruby alternative to Readline"
-        raise
-      end
-    end
-  end
-end
diff --git a/lib/pry/config/lazy.rb b/lib/pry/config/lazy.rb
index a521f918..4718465f 100644
--- a/lib/pry/config/lazy.rb
+++ b/lib/pry/config/lazy.rb
@@ -1,18 +1,15 @@
 class Pry
   class Config < Pry::BasicObject
-    # Wraps a block so it can have a name.
     # The primary purpose for instances of this class is to be used as a
     # configuration value that is computed upon each access, see {Pry.lazy}
-    # for more information.
+    # for more examples.
     #
     # @example
-    #   proc1 = proc {}
-    #   proc2 = Pry::Config::Lazy.new(&proc {})
-    #
-    #   proc1.is_a?(Pry::Config::Lazy)
-    #   #=> false
-    #   proc2.is_a?(Pry::Config::Lazy)
-    #   #=> true
+    #   num = 19
+    #   _pry_.config.foo = Pry::Config::Lazy.new(&proc { num += 1 })
+    #   _pry_.config.foo # => 20
+    #   _pry_.config.foo # => 21
+    #   _pry_.config.foo # => 22
     #
     # @api private
     # @since v0.12.0
diff --git a/lib/pry/config/memoization.rb b/lib/pry/config/memoization.rb
deleted file mode 100644
index f2e24388..00000000
--- a/lib/pry/config/memoization.rb
+++ /dev/null
@@ -1,48 +0,0 @@
-class Pry
-  class Config < Pry::BasicObject
-    module Memoization
-      MEMOIZED_METHODS = Hash.new { |h,k| h[k] = [] }
-
-      module ClassMethods
-        #
-        # Defines one or more methods who return a constant value after being
-        # called once.
-        #
-        # @example
-        #   class Foo
-        #     include Pry::Config::Memoization
-        #     def_memoized({
-        #       foo: proc {1+10},
-        #       bar: proc{"aaa"<<"a"}
-        #     })
-        #   end
-        #
-        # @param [{String => Proc}] method_table
-        #
-        # @return [void]
-        #
-        def def_memoized(method_table)
-          method_table.each do |method_name, method|
-            define_method(method_name) do
-              method_table[method_name] = instance_eval(&method) if method_table[method_name].equal? method
-              method_table[method_name]
-            end
-          end
-          MEMOIZED_METHODS[self] |= method_table.keys
-        end
-      end
-
-      def self.included(mod)
-        mod.extend(ClassMethods)
-      end
-
-      #
-      # @return [Array<Symbol>]
-      #   Returns the names of methods that have been defined by {ClassMethods#def_memoized}.
-      #
-      def memoized_methods
-        MEMOIZED_METHODS[self.class]
-      end
-    end
-  end
-end
diff --git a/lib/pry/pry_class.rb b/lib/pry/pry_class.rb
index b849717f..72618388 100644
--- a/lib/pry/pry_class.rb
+++ b/lib/pry/pry_class.rb
@@ -338,7 +338,7 @@ Readline version #{Readline::VERSION} detected - will not auto_resize! correctly
     @initial_session = true
     @session_finalized = nil
 
-    self.config = Pry::Config.new Pry::Config::Default.new
+    self.config = Pry::Config.new Pry::Config.defaults
     self.cli = false
     self.current_line = 1
     self.line_buffer = [""]
diff --git a/lib/pry/testable.rb b/lib/pry/testable.rb
index afc4dc25..695eded3 100644
--- a/lib/pry/testable.rb
+++ b/lib/pry/testable.rb
@@ -55,7 +55,7 @@ module Pry::Testable
   # @return [void]
   #
   def self.set_testenv_variables
-    Pry.config = Pry::Config.from_hash(TEST_DEFAULTS, Pry::Config::Default.new)
+    Pry.config = Pry::Config.from_hash TEST_DEFAULTS, Pry::Config.defaults
     Pry.config.hooks = Pry::Hooks.new
   end
 
@@ -65,6 +65,6 @@ module Pry::Testable
   # @return [void]
   #
   def self.unset_testenv_variables
-    Pry.config = Pry::Config.from_hash({}, Pry::Config::Default.new)
+    Pry.config = Pry::Config.from_hash({}, Pry::Config.defaults)
   end
 end