From 8db825300d2d0f46dc65addea53375e9209581ec Mon Sep 17 00:00:00 2001
From: Dmitry Maksyoma <ledestin@gmail.com>
Date: Sun, 6 Apr 2014 21:14:35 +1200
Subject: [PATCH] * Refactor.

Use a specific exception instead of ArgumentError, thus saving us from:
* Rescuing errors we didn't mean to rescue
OR
* Having an ugly being-rescue block at the start of #place.
---
 robot.rb           | 2 +-
 spec/state_spec.rb | 5 +++++
 state.rb           | 4 ++++
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/robot.rb b/robot.rb
index 79de386..056bc04 100644
--- a/robot.rb
+++ b/robot.rb
@@ -54,7 +54,7 @@ def place x, y, direction
     return unless @@table.contain? new_coords.x, new_coords.y
 
     @coords = new_coords
-  rescue ArgumentError
+  rescue StateArgumentError
   end
 
   def report
diff --git a/spec/state_spec.rb b/spec/state_spec.rb
index 9e55af8..c976172 100644
--- a/spec/state_spec.rb
+++ b/spec/state_spec.rb
@@ -6,4 +6,9 @@
     state = Robot::State.new 0, 0, 'NORTH'
     expect(state.to_s).to eq '0,0,NORTH'
   end
+
+  it 'raises State if a constructor argument is invalid' do
+    expect { Robot::State.new 'a', 0, 'NORTH' }.to \
+      raise_error Robot::StateArgumentError
+  end
 end
diff --git a/state.rb b/state.rb
index 9138050..f0fb92a 100644
--- a/state.rb
+++ b/state.rb
@@ -1,10 +1,14 @@
 require './direction'
 
 class Robot
+  class StateArgumentError < ArgumentError; end
+
   State = Struct.new(:x, :y, :direction) do
     def initialize x, y, direction
       self.x, self.y, self.direction =
 	Integer(x), Integer(y), Direction(direction)
+    rescue ArgumentError
+      raise StateArgumentError, $!.message
     end
 
     def to_s