From 2fa72a47cd4b8094f6c6d987ba37968747aa790a Mon Sep 17 00:00:00 2001
From: Phil Nash <phil@twobluecubes.com>
Date: Mon, 6 Jun 2011 08:21:21 +0100
Subject: [PATCH] Added ability to build custom Approx instance

---
 include/internal/catch_approx.hpp | 40 +++++++++++++++++++++++++++----
 projects/SelfTest/ApproxTests.cpp | 23 ++++++++++++++++++
 2 files changed, 58 insertions(+), 5 deletions(-)

diff --git a/include/internal/catch_approx.hpp b/include/internal/catch_approx.hpp
index 8a98a735..04e63df9 100644
--- a/include/internal/catch_approx.hpp
+++ b/include/internal/catch_approx.hpp
@@ -27,14 +27,44 @@ namespace Catch
             ///////////////////////////////////////////////////////////////////////////
             explicit Approx
             (
-                double d
+                double value
             )
             :   m_epsilon( std::numeric_limits<float>::epsilon()*100 ),
                 m_scale( 1.0 ),
-                m_d( d )
+                m_value( value )
             {
             }
             
+            ///////////////////////////////////////////////////////////////////////////
+            Approx
+            (
+                const Approx& other
+            )
+            :   m_epsilon( other.m_epsilon ),
+                m_scale( other.m_scale ),
+                m_value( other.m_value )
+            {
+            }
+
+            ///////////////////////////////////////////////////////////////////////////
+            static Approx custom
+            ()
+            {
+                return Approx( 0 );
+            }
+            
+            ///////////////////////////////////////////////////////////////////////////
+            Approx operator()
+            (
+                double value
+            )
+            {
+                Approx approx( value );
+                approx.epsilon( m_epsilon );
+                approx.scale( m_scale );
+                return approx;
+            }
+            
             ///////////////////////////////////////////////////////////////////////////
             friend bool operator == 
             (
@@ -43,7 +73,7 @@ namespace Catch
             )
             {
                 // Thanks to Richard Harris for his help refining this formula
-                return fabs( lhs - rhs.m_d ) < rhs.m_epsilon * (rhs.m_scale + (std::max)( fabs(lhs), fabs(rhs.m_d) ) );
+                return fabs( lhs - rhs.m_value ) < rhs.m_epsilon * (rhs.m_scale + (std::max)( fabs(lhs), fabs(rhs.m_value) ) );
             }
             
             ///////////////////////////////////////////////////////////////////////////
@@ -101,14 +131,14 @@ namespace Catch
             std::string toString() const
             {
                 std::ostringstream oss;
-                oss << "Approx( " << m_d << ")";
+                oss << "Approx( " << m_value << ")";
                 return oss.str();
             }
             
         private:
             double m_epsilon;
             double m_scale;
-            double m_d;
+            double m_value;
         };
     }
   
diff --git a/projects/SelfTest/ApproxTests.cpp b/projects/SelfTest/ApproxTests.cpp
index cdab6019..f9addb4e 100644
--- a/projects/SelfTest/ApproxTests.cpp
+++ b/projects/SelfTest/ApproxTests.cpp
@@ -82,3 +82,26 @@ TEST_CASE
     REQUIRE( 1.234f == Approx( dMedium ) );
     REQUIRE( dMedium == Approx( 1.234f ) );
 }
+
+///////////////////////////////////////////////////////////////////////////////
+TEST_CASE
+(
+    "./succeeding/Approx/custom", 
+    "Use a custom approx"
+)
+{
+    double d = 1.23;
+    
+    Approx approx = Approx::custom().epsilon( 0.005 );
+    
+    REQUIRE( d == approx( 1.23 ) );
+    REQUIRE( d == approx( 1.22 ) );
+    REQUIRE( d == approx( 1.24 ) );
+    REQUIRE( d != approx( 1.25 ) );
+    
+    REQUIRE( approx( d ) == 1.23 );
+    REQUIRE( approx( d ) == 1.22 );
+    REQUIRE( approx( d ) == 1.24 );
+    REQUIRE( approx( d ) != 1.25 );
+}
+