SGRawValue< T > Class Template Reference
Abstract base class for a raw value. More...
#include <props.hxx>
Public Member Functions | |
| SGRawValue () | |
| Constructor. | |
| virtual | ~SGRawValue () |
| Destructor. | |
| virtual T | getValue () const =0 |
| Return the underlying value. | |
| virtual bool | setValue (T value)=0 |
| Assign a new underlying value. | |
| virtual simgear::props::Type | getType () const |
| Return the type tag for this raw value type. | |
Static Public Member Functions | |
| static T | DefaultValue () |
| The default underlying value for this type. | |
Detailed Description
template<class T>
class SGRawValue< T >
Abstract base class for a raw value.
The property manager is implemented in two layers. The SGPropertyNode is the highest and most abstract layer, representing an LValue/RValue pair: it records the position of the property in the property tree and contains facilities for navigation to other nodes. It is guaranteed to be persistent: the SGPropertyNode will not change during a session, even if the property is bound and unbound multiple times.
When the property value is not managed internally in the SGPropertyNode, the SGPropertyNode will contain a reference to an SGRawValue (this class), which provides an abstract way to get, set, and clone the underlying value. The SGRawValue may change frequently during a session as a value is retyped or bound and unbound to various data source, but the abstract SGPropertyNode layer insulates the application from those changes.
The SGPropertyNode class always keeps a *copy* of a raw value, not the original one passed to it; if you override a derived class but do not replace the clone method, strange things will happen.
All derived SGRawValue classes must implement getValue, setValue, and clone for the appropriate type.
- See also:
- SGPropertyNode
- SGRawValuePointer
- SGRawValueFunctions
- SGRawValueFunctionsIndexed
- SGRawValueMethods
- SGRawValueMethodsIndexed
- SGRawValueContainer
Definition at line 303 of file props.hxx.
Constructor & Destructor Documentation
| SGRawValue< T >::SGRawValue | ( | ) | [inline] |
Member Function Documentation
| static T SGRawValue< T >::DefaultValue | ( | ) | [inline, static] |
The default underlying value for this type.
Every raw value has a default; the default is false for a boolean, 0 for the various numeric values, and "" for a string. If additional types of raw values are added in the future, they may need different kinds of default values (such as epoch for a date type). The default value is used when creating new values.
| virtual T SGRawValue< T >::getValue | ( | ) | const [pure virtual] |
Return the underlying value.
- Returns:
- The actual value for the property.
- See also:
- setValue
Implemented in SGRawValuePointer< T >, SGRawValueFunctions< T >, SGRawValueFunctionsIndexed< T >, SGRawValueMethods< C, T >, SGRawValueMethodsIndexed< C, T >, and SGRawValueContainer< T >.
| virtual bool SGRawValue< T >::setValue | ( | T | value | ) | [pure virtual] |
Assign a new underlying value.
If the new value cannot be set (because this is a read-only raw value, or because the new value is not acceptable for some reason) this method returns false and leaves the original value unchanged.
- Parameters:
-
value The actual value for the property.
- Returns:
- true if the value was set successfully, false otherwise.
- See also:
- getValue
Implemented in SGRawValuePointer< T >, SGRawValueFunctions< T >, SGRawValueFunctionsIndexed< T >, SGRawValueMethods< C, T >, SGRawValueMethodsIndexed< C, T >, and SGRawValueContainer< T >.
The documentation for this class was generated from the following file:
