Add bin and edit workflow

bin/gems/pry-0.15.2/lib/pry/commands/watch_expression.rb

@@ -0,0 +1,108 @@
+# frozen_string_literal: true
+
+class Pry
+  class Command
+    class WatchExpression < Pry::ClassCommand
+      match 'watch'
+      group 'Context'
+      description 'Watch the value of an expression and print a notification ' \
+                  'whenever it changes.'
+      command_options use_prefix: false, state: %i[watch_expressions]
+
+      banner <<-'BANNER'
+        Usage: watch [EXPRESSION]
+               watch
+               watch --delete [INDEX]
+
+        watch [EXPRESSION] adds an expression to the list of those being watched.
+        It will be re-evaluated every time you hit enter in pry. If its value has
+        changed, the new value will be printed to the console.
+
+        This is useful if you are step-through debugging and want to see how
+        something changes over time.  It's also useful if you're trying to write
+        a method inside pry and want to check that it gives the right answers
+        every time you redefine it.
+
+        watch on its own displays all the currently watched expressions and their
+        values, and watch --delete [INDEX] allows you to delete expressions from
+        the list being watched.
+      BANNER
+
+      def options(opt)
+        opt.on :d, :delete,
+               "Delete the watch expression with the given index. If no index " \
+               "is given; clear all watch expressions.",
+               optional_argument: true, as: Integer
+        opt.on :l, :list,
+               "Show all current watch expressions and their values. Calling " \
+               "watch with no expressions or options will also show the watch " \
+               "expressions."
+      end
+
+      def process
+        if opts.present?(:delete)
+          delete opts[:delete]
+        elsif opts.present?(:list) || args.empty?
+          list
+        else
+          add_hook
+          add_expression
+        end
+      end
+
+      private
+
+      def expressions
+        state.watch_expressions ||= []
+      end
+
+      def delete(index)
+        if index
+          output.puts "Deleting watch expression ##{index}: #{expressions[index - 1]}"
+          expressions.delete_at(index - 1)
+        else
+          output.puts "Deleting all watched expressions"
+          expressions.clear
+        end
+      end
+
+      def list
+        if expressions.empty?
+          output.puts "No watched expressions"
+        else
+          pry_instance.pager.open do |pager|
+            pager.puts "Listing all watched expressions:"
+            pager.puts ""
+            expressions.each_with_index do |expr, index|
+              pager.print with_line_numbers(expr.to_s, index + 1)
+            end
+            pager.puts ""
+          end
+        end
+      end
+
+      def eval_and_print_changed(output)
+        expressions.each do |expr|
+          expr.eval!
+          output.puts "#{blue 'watch'}: #{expr}" if expr.changed?
+        end
+      end
+
+      def add_expression
+        expressions << Expression.new(pry_instance, target, arg_string)
+        output.puts "Watching #{Code.new(arg_string).highlighted}"
+      end
+
+      def add_hook
+        hook = %i[after_eval watch_expression]
+        return if pry_instance.hooks.hook_exists?(*hook)
+
+        pry_instance.hooks.add_hook(*hook) do |_, pry_instance|
+          eval_and_print_changed pry_instance.output
+        end
+      end
+    end
+
+    Pry::Commands.add_command(Pry::Command::WatchExpression)
+  end
+end