From d6052a5a27470a8389c2ffc08aa8fd8d8cc3f672 Mon Sep 17 00:00:00 2001
From: Eivind Kvedalen <eivind@kvedalen.name>
Date: Sun, 27 Mar 2016 01:29:25 +0100
Subject: [PATCH] Quantity: Added -= and += operators.

---
 src/Base/Quantity.cpp | 21 +++++++++++++++++++++
 src/Base/Quantity.h   |  2 ++
 2 files changed, 23 insertions(+)

diff --git a/src/Base/Quantity.cpp b/src/Base/Quantity.cpp
index 4bb599c5e..18206c096 100644
--- a/src/Base/Quantity.cpp
+++ b/src/Base/Quantity.cpp
@@ -113,6 +113,17 @@ Quantity Quantity::operator +(const Quantity &p) const
         throw Base::Exception("Quantity::operator +(): Unit mismatch in plus operation");
     return Quantity(this->_Value + p._Value,this->_Unit);
 }
+
+Quantity& Quantity::operator +=(const Quantity &p)
+{
+    if(this->_Unit != p._Unit)
+        throw Base::Exception("Quantity::operator +=(): Unit mismatch in plus operation");
+
+    _Value += p._Value;
+
+    return *this;
+}
+
 Quantity Quantity::operator -(const Quantity &p) const
 {
     if(this->_Unit != p._Unit) 
@@ -120,6 +131,16 @@ Quantity Quantity::operator -(const Quantity &p) const
     return Quantity(this->_Value - p._Value,this->_Unit);
 }
 
+Quantity& Quantity::operator -=(const Quantity &p)
+{
+    if(this->_Unit != p._Unit)
+        throw Base::Exception("Quantity::operator -=(): Unit mismatch in minus operation");
+
+    _Value -= p._Value;
+
+    return *this;
+}
+
 Quantity Quantity::operator -(void) const
 {
     return Quantity(-(this->_Value),this->_Unit);
diff --git a/src/Base/Quantity.h b/src/Base/Quantity.h
index 4c4edacd8..fd722437e 100644
--- a/src/Base/Quantity.h
+++ b/src/Base/Quantity.h
@@ -53,7 +53,9 @@ public:
     //@{
     Quantity operator *(const Quantity &p) const;
     Quantity operator +(const Quantity &p) const;
+    Quantity& operator +=(const Quantity &p);
     Quantity operator -(const Quantity &p) const;
+    Quantity& operator -=(const Quantity &p);
     Quantity operator -(void) const;
     Quantity operator /(const Quantity &p) const;
     bool operator ==(const Quantity&) const;