move typed getters to Property & drop fallback interface

Better usability for user code if they deserialize individual Propertys.

The fallback variants are not used internally and are redundant
because there is a separate default behavior.

Removed the msg parameter for Property exceptions.
It was only used by a single edge-case which didn't really justify
the use of the exception anyway.
Instead allow `undefined` to be instantiated without parameters
because the Property does not know its own name.

Author: v4hn

core/include/moveit/task_constructor/properties.h

@@ -81,13 +81,40 @@ class Property
 	Property();
 
 	/// base class for Property exceptions
-	class error;
+	class error : public std::runtime_error
+	{
+	protected:
+		std::string property_name_;
+		std::string msg_;
+
+	public:
+		explicit error(const std::string& msg);
+		const std::string& name() const { return property_name_; }
+		void setName(const std::string& name);
+		const char* what() const noexcept override { return msg_.c_str(); }
+	};
+
 	/// exception thrown when accessing an undeclared property
-	class undeclared;
+	class undeclared : public Property::error
+	{
+	public:
+		explicit undeclared(const std::string& name);
+	};
+
 	/// exception thrown when accessing an undefined property
-	class undefined;
+	class undefined : public Property::error
+	{
+	public:
+		explicit undefined();
+		explicit undefined(const std::string& name);
+	};
+
 	/// exception thrown when trying to set a value not matching the declared type
-	class type_error;
+	class type_error : public Property::error
+	{
+	public:
+		explicit type_error(const std::string& current_type, const std::string& declared_type);
+	};
 
 	using SourceFlags = uint;
 	/// function callback used to initialize property value from another PropertyMap
@@ -101,12 +128,22 @@ class Property
 	/// reset to default value (which can be empty)
 	void reset();
 
-	/// the current value defined or will the fallback be used?
-	inline bool defined() const { return !value_.empty(); }
+	/// is a value defined?
+	inline bool defined() const { return !(value_.empty() && default_.empty()); }
 
-	/// get current value (or default if not defined)
+	/// get current value (or default if not set)
 	inline const boost::any& value() const { return value_.empty() ? default_ : value_; }
 	inline boost::any& value() { return value_.empty() ? default_ : value_; }
+
+	/// get typed value of property. Throws bad_any_cast on type mismatch, undefined if !defined().
+	template <typename T>
+	inline const T& value() const {
+		const boost::any& v{ value() };
+		if (v.empty())
+			throw Property::undefined();
+		return boost::any_cast<const T&>(value());
+	}
+
 	/// get default value
 	const boost::any& defaultValue() const { return default_; }
 
@@ -142,34 +179,6 @@ class Property
 	InitializerFunction initializer_;
 };
 
-class Property::error : public std::runtime_error
-{
-protected:
-	std::string property_name_;
-	std::string msg_;
-
-public:
-	explicit error(const std::string& msg);
-	const std::string& name() const { return property_name_; }
-	void setName(const std::string& name);
-	const char* what() const noexcept override { return msg_.c_str(); }
-};
-class Property::undeclared : public Property::error
-{
-public:
-	explicit undeclared(const std::string& name, const std::string& msg = "undeclared");
-};
-class Property::undefined : public Property::error
-{
-public:
-	explicit undefined(const std::string& name, const std::string& msg = "undefined");
-};
-class Property::type_error : public Property::error
-{
-public:
-	explicit type_error(const std::string& current_type, const std::string& declared_type);
-};
-
 // hasSerialize<T>::value provides a true/false constexpr depending on whether operator<< is supported.
 // This uses SFINAE, extracted from https://jguegant.github.io/blogs/tech/sfinae-introduction.html
 template <typename T, typename = std::ostream&>
@@ -318,19 +327,15 @@ class PropertyMap
 	/// Get the value of a property. Throws undeclared if unknown name
 	const boost::any& get(const std::string& name) const;
 
-	/// Get typed value of property. Throws undeclared, undefined, or bad_any_cast.
+	/// Get typed value of property. Throws undeclared or bad_any_cast.
 	template <typename T>
 	const T& get(const std::string& name) const {
-		const boost::any& value = get(name);
-		if (value.empty())
-			throw Property::undefined(name);
-		return boost::any_cast<const T&>(value);
-	}
-	/// get typed value of property, using fallback if undefined. Throws bad_any_cast on type mismatch.
-	template <typename T>
-	const T& get(const std::string& name, const T& fallback) const {
-		const boost::any& value = get(name);
-		return (value.empty()) ? fallback : boost::any_cast<const T&>(value);
+		try {
+			return property(name).value<T>();
+		} catch (Property::undefined& e) {
+			e.setName(name);
+			throw e;
+		}
 	}
 
 	/// count number of defined properties from given list

core/src/properties.cpp

@@ -239,7 +239,7 @@ void PropertyMap::set<boost::any>(const std::string& name, const boost::any& val
 	auto range = props_.equal_range(name);
 	if (range.first == range.second) {  // name is not yet declared
 		if (value.empty())
-			throw Property::undeclared(name, "trying to set undeclared property '" + name + "' with NULL value");
+			throw std::runtime_error("trying to set undeclared property '" + name + "' with NULL value");
 		auto it = props_.insert(range.first, std::make_pair(name, Property(value.type(), "", boost::any())));
 		it->second.setValue(value);
 	} else
@@ -308,11 +308,13 @@ void Property::error::setName(const std::string& name) {
 	msg_ = "Property '" + name + "': " + std::runtime_error::what();
 }
 
-Property::undeclared::undeclared(const std::string& name, const std::string& msg) : Property::error(msg) {
+Property::undeclared::undeclared(const std::string& name) : Property::error("undeclared") {
 	setName(name);
 }
 
-Property::undefined::undefined(const std::string& name, const std::string& msg) : Property::error(msg) {
+Property::undefined::undefined() : Property::error("undefined") {}
+
+Property::undefined::undefined(const std::string& name) : Property::undefined() {
 	setName(name);
 }
 

core/test/test_properties.cpp

@@ -17,7 +17,6 @@ TEST(Property, standard) {
 
 	EXPECT_THROW(props.get<double>("double4"), Property::undefined);
 	EXPECT_FALSE(props.property("double4").defined());
-	EXPECT_EQ(props.get<double>("double4", 0.0), 0.0);
 
 	props.set("double3", 3.0);
 	EXPECT_EQ(props.get<double>("double3"), 3.0);