DOUBLE_PROPERTY: add const and non-const reference getter

GUI/Model/Descriptor/DoubleProperty.h

@@ -110,11 +110,12 @@ void rwProperty(Streamer& s, const QString& tag, DoubleProperty& d);
 // clang-format off
 
 //! Add a member, a getter and a setter for a DoubleProperty
-#define DOUBLE_PROPERTY(nameLower, nameUpper)                    \
-protected:                                                       \
-    DoubleProperty m_##nameLower;                                \
-public:                                                          \
-    DoubleDescriptor nameLower() const { return m_##nameLower; } \
+#define DOUBLE_PROPERTY(nameLower, nameUpper)                           \
+protected:                                                              \
+    DoubleProperty m_##nameLower;                                       \
+public:                                                                 \
+    DoubleProperty& nameLower() { return m_##nameLower; }               \
+    const DoubleProperty& nameLower() const { return m_##nameLower; }   \
     void set##nameUpper(double v) { m_##nameLower.set(v); }
 
 // clang-format on

GUI/Model/Model/ParameterTreeUtils.cpp

@@ -411,7 +411,7 @@ void ParameterTreeBuilder::addBackground(ParameterLabelItem* instrumentLabel,
 {
     if (auto* b = dynamic_cast<ConstantBackgroundItem*>(backgroundItem))
         addParameterItem(instrumentLabel, b->backgroundValue(),
-                         labelWithUnit("Constant background", b->backgroundValue().unit));
+                         labelWithUnit("Constant background", b->backgroundValue().unit()));
 }
 
 void ParameterTreeBuilder::addPolarization(ParameterLabelItem* instrumentLabel,

Tests/Unit/GUI/TestDetectorItems.cpp

@@ -43,8 +43,8 @@ TEST_F(TestDetectorItems, resolutionFunctionUnit)
     auto* p = dynamic_cast<ResolutionFunction2DGaussianItem*>(
         detector.resolutionFunctionSelection().currentItem());
     EXPECT_NE(p, nullptr);
-    EXPECT_EQ(asString(p->sigmaX().unit), "mm");
-    EXPECT_EQ(asString(p->sigmaY().unit), "mm");
+    EXPECT_EQ(asString(p->sigmaX().unit()), "mm");
+    EXPECT_EQ(asString(p->sigmaY().unit()), "mm");
 
     SphericalDetectorItem sphericalDetector;
     sphericalDetector.setResolutionFunctionType<ResolutionFunctionNoneItem>();
@@ -52,6 +52,6 @@ TEST_F(TestDetectorItems, resolutionFunctionUnit)
     p = dynamic_cast<ResolutionFunction2DGaussianItem*>(
         sphericalDetector.resolutionFunctionSelection().currentItem());
     EXPECT_NE(p, nullptr);
-    EXPECT_EQ(asString(p->sigmaX().unit), unitAsString(Unit::degree));
-    EXPECT_EQ(asString(p->sigmaY().unit), unitAsString(Unit::degree));
+    EXPECT_EQ(asString(p->sigmaX().unit()), unitAsString(Unit::degree));
+    EXPECT_EQ(asString(p->sigmaY().unit()), unitAsString(Unit::degree));
 }