Refactor Config

Fixes pry#1843 (Rework the Pry config)

There are a few breaking changes. They are mostly minor, so I decided not to
indroduce deprecations because it will considerable slow things down.

Key changes:

* `Pry.lazy` was replaced with `Pry::Configuration::LazyValue`

  The config accepts three values now `LazyValue`, `MemoizedValue` and simply
  `Value`. The main difference is that:
    - `Value` is any value, including procs (so that an option returns a raw
      proc)
    - `LazyValue` is a proc that is call on every invocation of an option
    - `MemoizedValue` is a value that is called only once (and then the option
      always returns the return value of the )

* `Pry.config.history` was a meta-option that held suboptions. However, the new
  config doesn't permit that (unless you know what you do)

  Instead, we introduce a few options. For example:
    - `Pry.config.history.histignore` becomes `Pry.config.history_ignorelist`
    - `Pry.config.history.file` becomes `Pry.config.history_file`
    - and so on

  This was done so we can simplify configuration merging. Inlining option makes
  configuration implementation simpler, without losing much. The rule is that
  you want to keep your options under your prefix (if you are a
  plugin). Therefore, say, `Pry.config.pry_rescue.*` should be
  `Pry.config.pry_rescue_*` if you need merging.

The rest should behave in a similar fashion (and I rely heavily on our test
suite to claim so).

CHANGELOG.md

@@ -8,6 +8,9 @@
 * Added ability to forward ARGV to a Pry session via `--` (or `-`) when
   launching Pry from shell
   ([#1902](https://github.com/pry/pry/commit/5cd65d3c0eb053f6edcdf571eea5d0cd990626ed))
+* Added `Pry::Config::LazyValue` & `Pry::Config::MemoizedValue`, which allow
+  storing callable procs in the config
+  ([#2024](https://github.com/pry/pry/pull/2024))
 
 #### API changes
 
@@ -65,6 +68,8 @@
   ([#2001](https://github.com/pry/pry/pull/2001))
 * Deleted `Pry::BlockCommand#opts` (use `#context` instead)
   ([#2003](https://github.com/pry/pry/pull/2003))
+* Deleted `Pry.lazy` (use `Pry::Config::LazyValue` instead)
+  ([#2024](https://github.com/pry/pry/pull/2024))
 
 #### Bug fixes
 

lib/pry.rb

@@ -45,9 +45,10 @@
 require 'pry/commands/ls/methods_helper'
 require 'pry/commands/ls'
 
-require 'pry/config/convenience'
-require 'pry/config/lazy'
-require 'pry/config/behavior'
+require 'pry/config/attributable'
+require 'pry/config/value'
+require 'pry/config/memoized_value'
+require 'pry/config/lazy_value'
 require 'pry/config'
 
 require 'pry/pry_class'

lib/pry/commands/ls/formatter.rb

@@ -20,7 +20,7 @@ def write_out
         private
 
         def color(type, str)
-          Pry::Helpers::Text.send pry_instance.config.ls["#{type}_color"], str
+          Pry::Helpers::Text.send pry_instance.config.ls.send("#{type}_color"), str
         end
 
         # Add a new section to the output.

lib/pry/config.rb

@@ -1,37 +1,180 @@
+require 'ostruct'
+
 class Pry
-  # The Pry config.
-  # @api public
-  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) },
+  # @api private
+  class Config
+    extend Attributable
+
+    # @return [IO, #readline] he object from which Pry retrieves its lines of
+    #   input
+    attribute :input
+
+    # @return [IO, #puts] where Pry should output results provided by {input}
+    attribute :output
+
+    # @return [Pry::CommandSet]
+    attribute :commands
+
+    # @return [Proc] the printer for Ruby expressions (not commands)
+    attribute :print
+
+    # @return [Proc] the printer for exceptions
+    attribute :exception_handler
+
+    # @return [Array] Exception that Pry shouldn't rescue
+    attribute :unrescued_exceptions
+
+    # @deprecated
+    # @return [Array] Exception that Pry shouldn't rescue
+    attribute :exception_whitelist
+
+    # @return [Integer] The number of lines of context to show before and after
+    #   exceptions
+    attribute :default_window_size
+
+    # @return [Pry::Hooks]
+    attribute :hooks
+
+    # @return [Pry::Prompt]
+    attribute :prompt
+
+    # @return [String] The display name that is part of the prompt
+    attribute :prompt_name
+
+    # @return [Array<Object>] the list of objects that are known to have a
+    #   1-line #inspect output suitable for prompt
+    attribute :prompt_safe_contexts
+
+    # If it is a String, then that String is used as the shell
+    # command to invoke the editor.
+    #
+    # If it responds to #call is callable then `file`, `line`, and `reloading`
+    # are passed to it. `reloading` indicates whether Pry will be reloading code
+    # after the shell command returns. All parameters are optional.
+    # @return [String, #call]
+    attribute :editor
+
+    # A string that must precede all commands. For example, if is is
+    # set to "%", the "cd" command must be invoked as "%cd").
+    # @return [String]
+    attribute :command_prefix
+
+    # @return [Boolean]
+    attribute :color
+
+    # @return [Boolean]
+    attribute :pager
+
+    # @return [Boolean] whether the global ~/.pryrc should be loaded
+    attribute :should_load_rc
+
+    # @return [Boolean] whether the local ./.pryrc should be loaded
+    attribute :should_load_local_rc
+
+    # @return [Boolean]
+    attribute :should_load_plugins
+
+    # @return [Boolean] whether to load files specified with the -r flag
+    attribute :should_load_requires
+
+    # @return [Boolean] whether to disable edit-method's auto-reloading behavior
+    attribute :disable_auto_reload
+
+    # Whether Pry should trap SIGINT and cause it to raise an Interrupt
+    # exception. This is only useful on JRuby, MRI does this for us.
+    # @return [Boolean]
+    attribute :should_trap_interrupts
+
+    # @return [Pry::History]
+    attribute :history
+
+    # @return [Boolean]
+    attribute :history_save
+
+    # @return [Boolean]
+    attribute :history_load
+
+    # @return [String]
+    attribute :history_file
+
+    # @return [Array<String,Regexp>]
+    attribute :history_ignorelist
+
+    # @return [Array<String>] Ruby files to be required
+    attribute :requires
+
+    # @return [Integer] how many input/output lines to keep in memory
+    attribute :memory_size
+
+    # @return [Proc]
+    attribute :control_d_handler
+
+    # @return [Proc] The proc that runs system commands
+    attribute :system
+
+    # @return [Boolean]
+    attribute :auto_indent
+
+    # @return [Boolean]
+    attribute :correct_indent
+
+    # @return [Boolean] whether or not display a warning when a command name
+    #   collides with a method/local in the current context.
+    attribute :collision_warning
+
+    # @return [Hash{Symbol=>Proc}]
+    attribute :extra_sticky_locals
+
+    # @return [#build_completion_proc] a completer to use
+    attribute :completer
+
+    # @return [Boolean] suppresses whereami output on `binding.pry`
+    attribute :quiet
+
+    # @return [Boolean] displays a warning about experience improvement on
+    #   Windows
+    attribute :windows_console_warning
+
+    # @return [Proc]
+    attribute :command_completions
+
+    # @return [Proc]
+    attribute :file_completions
+
+    # @return [Hash]
+    attribute :ls
+
+    # @return [String] a line of code to execute in context before the session
+    #   starts
+    attribute :exec_string
+
+    # @return [String]
+    attribute :output_prefix
+
+    def initialize
+      merge!(
+        input: MemoizedValue.new { lazy_readline },
         output: $stdout.tap { |out| out.sync = true },
         commands: Pry::Commands,
-        prompt_name: Pry::Prompt::DEFAULT_NAME,
+        prompt_name: 'pry',
         prompt: Pry::Prompt[:default],
-        prompt_safe_contexts: Pry::Prompt::SAFE_CONTEXTS,
+        prompt_safe_contexts: [String, Numeric, Symbol, nil, true, false],
         print: Pry::ColorPrinter.method(:default),
         quiet: false,
         exception_handler: Pry::ExceptionHandler.method(:handle_exception),
+
         unrescued_exceptions: [
           ::SystemExit, ::SignalException, Pry::TooSafeException
         ],
 
-        exception_whitelist: Pry.lazy do
-          defaults.output.puts(
+        exception_whitelist: MemoizedValue.new do
+          output.puts(
             '[warning] Pry.config.exception_whitelist is deprecated, ' \
             'please use Pry.config.unrescued_exceptions instead.'
           )
-          [::SystemExit, ::SignalException, Pry::TooSafeException]
+          unrescued_exceptions
         end,
 
-        # The default hooks - display messages when beginning and ending Pry
-        # sessions.
         hooks: Pry::Hooks.default,
         pager: true,
         system: Pry::SystemCommandHandler.method(:default),
@@ -42,41 +185,84 @@ def self.defaults
         should_load_local_rc: true,
         should_trap_interrupts: Pry::Helpers::Platform.jruby?,
         disable_auto_reload: false,
-        command_prefix: "",
+        command_prefix: '',
         auto_indent: Pry::Helpers::BaseHelpers.use_ansi_codes?,
         correct_indent: true,
         collision_warning: false,
-        output_prefix: "=> ",
+        output_prefix: '=> ',
         requires: [],
         should_load_requires: true,
         should_load_plugins: true,
         windows_console_warning: true,
         control_d_handler: Pry::ControlDHandler.method(:default),
         memory_size: 100,
         extra_sticky_locals: {},
-        command_completions: proc { defaults.commands.keys },
-        file_completions: proc { Dir["."] },
-        ls: Pry::Config.from_hash(Pry::Command::Ls::DEFAULT_OPTIONS),
+        command_completions: proc { commands.keys },
+        file_completions: proc { Dir['.'] },
+        ls: OpenStruct.new(Pry::Command::Ls::DEFAULT_OPTIONS),
         completer: Pry::InputCompleter,
-        history: {
-          should_save: true,
-          should_load: true,
-          file: Pry::History.default_file
-        },
-        exec_string: ""
+        history_save: true,
+        history_load: true,
+        history_file: Pry::History.default_file,
+        history_ignorelist: [],
+        history: MemoizedValue.new do
+          if defined?(input::HISTORY)
+            Pry::History.new(history: input::HISTORY)
+          else
+            Pry::History.new
+          end
+        end,
+        exec_string: ''
       )
+
+      @custom_attrs = {}
+    end
+
+    def merge!(config_hash)
+      config_hash.each_pair { |attr, value| __send__("#{attr}=", value) }
+      self
+    end
+
+    def merge(config_hash)
+      dup.merge!(config_hash)
+    end
+
+    def []=(attr, value)
+      @custom_attrs[attr.to_s] = Config::Value.new(value)
     end
 
-    def self.shortcuts
-      Convenience::SHORTCUTS
+    def [](attr)
+      @custom_attrs[attr.to_s].call
     end
 
-    # @api private
-    def self.lazy_readline(defaults)
+    def method_missing(method_name, *args, &block)
+      name = method_name.to_s
+
+      if name.end_with?('=')
+        self[name[0..-2]] = args.first
+      elsif @custom_attrs.key?(name)
+        self[name]
+      else
+        super
+      end
+    end
+
+    def respond_to_missing?(method_name, include_all = false)
+      @custom_attrs.key?(method_name.to_s.tr('=', '')) || super
+    end
+
+    def initialize_dup(other)
+      super
+      @custom_attrs = @custom_attrs.dup
+    end
+
+    private
+
+    def lazy_readline
       require 'readline'
       ::Readline
     rescue LoadError
-      defaults.output.puts(
+      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" \
@@ -85,6 +271,5 @@ def self.lazy_readline(defaults)
       )
       raise
     end
-    private_class_method :lazy_readline
   end
 end

lib/pry/config/attributable.rb

@@ -0,0 +1,20 @@
+class Pry
+  class Config
+    # Attributable provides the ability to create "attribute"
+    # accessors. Attribute accessors create a standard "attr_writer" and a
+    # customised "attr_reader". This reader is Proc-aware (lazy).
+    #
+    # @since ?.?.?
+    # @api private
+    module Attributable
+      def attribute(attr_name)
+        define_method(attr_name) do
+          value = Config::Value.new(instance_variable_get("@#{attr_name}"))
+          value.call
+        end
+
+        attr_writer(attr_name)
+      end
+    end
+  end
+end