Expression class: Improved error message when resolving a variable fails.

src/App/Expression.cpp

@@ -989,7 +989,7 @@ const Property * VariableExpression::getProperty() const
     if (prop)
         return prop;
     else
-        throw ExpressionError(std::string("Property '") + var.getPropertyName() + std::string("' not found."));
+        throw Expression::Exception(var.resolveErrorString().c_str());
 }
 
 /**

src/App/ObjectIdentifier.cpp

@@ -865,6 +865,13 @@ ObjectIdentifier ObjectIdentifier::parse(const DocumentObject *docObj, const std
         throw Base::Exception("Invalid property specification.");
 }
 
+std::string ObjectIdentifier::resolveErrorString() const
+{
+    ResolveResults result(*this);
+
+    return result.resolveErrorString();
+}
+
 /**
  * @brief << operator, used to add a component to the object identifier.
  * @param value Component object
@@ -1111,3 +1118,17 @@ ObjectIdentifier::ResolveResults::ResolveResults(const ObjectIdentifier &oi)
 {
     oi.resolve(*this);
 }
+
+std::string ObjectIdentifier::ResolveResults::resolveErrorString() const
+{
+    if (resolvedDocument == 0)
+        return std::string("Document not found: ") + resolvedDocumentName.toString();
+    else if (resolvedDocumentObject == 0)
+        return std::string("Document object not found: ") + resolvedDocumentObjectName.toString();
+    else if (resolvedProperty == 0)
+        return std::string("Property not found: ") + propertyName;
+
+    assert(false);
+
+    return "";
+}

src/App/ObjectIdentifier.h

@@ -229,6 +229,8 @@ public:
 
     static ObjectIdentifier parse(const App::DocumentObject *docObj, const std::string & str);
 
+    std::string resolveErrorString() const;
+
 protected:
 
     struct ResolveResults {
@@ -242,6 +244,8 @@ protected:
         String resolvedDocumentObjectName;
         App::Property * resolvedProperty;
         std::string propertyName;
+
+        std::string resolveErrorString() const;
     };
 
     std::string getPythonAccessor() const;