Ipopt::TaggedObject Class Reference

TaggedObject class. More...

#include <IpTaggedObject.hpp>

Inheritance diagram for Ipopt::TaggedObject:
Inheritance graph
[legend]

List of all members.

Public Types

typedef std::pair< const
TaggedObject *, unsigned int > 
Tag
 Type for the Tag values.

Public Member Functions

 TaggedObject ()
 Constructor.
virtual ~TaggedObject ()
 Destructor.
Tag GetTag () const
 Users of TaggedObjects call this to update their own internal tags every time they perform the expensive operation.
bool HasChanged (const Tag comparison_tag) const
 Users of TaggedObjects call this to check if the object HasChanged since they last updated their own internal tag.

Protected Member Functions

void ObjectChanged ()
 Objects derived from TaggedObject MUST call this method every time their internal state changes to update the internal tag for comparison.

Private Member Functions

Default Compiler Generated Methods (Hidden to avoid

implicit creation/calling).

These methods are not implemented and we do not want the compiler to implement them for us, so we declare them private and do not define them. This ensures that they will not be implicitly created/called.



 TaggedObject (const TaggedObject &)
 Copy Constructor.
void operator= (const TaggedObject &)
 Overloaded Equals Operator.

Private Attributes

Tag::second_type tagcount_
 The tag indicating the current state of the object.
Index cache_priority_
 The index indicating the cache priority for this TaggedObject.

Detailed Description

TaggedObject class.

Often, certain calculations or operations are expensive, and it can be very inefficient to perform these calculations again if the input to the calculation has not changed since the result was last stored. This base class provides an efficient mechanism to update a tag, indicating that the object has changed. Users of a TaggedObject class, need their own Tag data member to keep track of the state of the TaggedObject, the last time they performed a calculation. A basic use case for users of a class inheriting from TaggedObject follows like this:

1. Initialize your own Tag by its default constructor.

2. Before an expensive calculation, check if the TaggedObject has changed, passing in your own Tag, indicating the last time you used the object for the calculation. If it has changed, perform the calculation again, and store the result. If it has not changed, simply return the stored result.

Here is a simple example:

          if (vector.HasChanged(my_vector_tag_)) {
            my_vector_tag_ = vector.GetTag();
            result = PerformExpensiveCalculation(vector);
            return result;
          }
          else {
            return result;
          }
   

Objects derived from TaggedObject must indicate that they have changed to the base class using the protected member function ObjectChanged(). For example, a Vector class, inside its own set method, MUST call ObjectChanged() to update the internally stored tag for comparison.

Definition at line 61 of file IpTaggedObject.hpp.


Member Typedef Documentation

typedef std::pair<const TaggedObject*, unsigned int> Ipopt::TaggedObject::Tag

Type for the Tag values.

To make the tag unique among all objects, we include the memory address of the object into the tag value.

Definition at line 70 of file IpTaggedObject.hpp.


Constructor & Destructor Documentation

Ipopt::TaggedObject::TaggedObject (  )  [inline]

Constructor.

Definition at line 73 of file IpTaggedObject.hpp.

virtual Ipopt::TaggedObject::~TaggedObject (  )  [inline, virtual]

Destructor.

Definition at line 84 of file IpTaggedObject.hpp.

Ipopt::TaggedObject::TaggedObject ( const TaggedObject  )  [private]

Copy Constructor.


Member Function Documentation

Tag Ipopt::TaggedObject::GetTag (  )  const [inline]

Users of TaggedObjects call this to update their own internal tags every time they perform the expensive operation.

Definition at line 91 of file IpTaggedObject.hpp.

bool Ipopt::TaggedObject::HasChanged ( const Tag  comparison_tag  )  const [inline]

Users of TaggedObjects call this to check if the object HasChanged since they last updated their own internal tag.

Definition at line 101 of file IpTaggedObject.hpp.

void Ipopt::TaggedObject::ObjectChanged (  )  [inline, protected]

Objects derived from TaggedObject MUST call this method every time their internal state changes to update the internal tag for comparison.

Definition at line 110 of file IpTaggedObject.hpp.

void Ipopt::TaggedObject::operator= ( const TaggedObject  )  [private]

Member Data Documentation

Tag::second_type Ipopt::TaggedObject::tagcount_ [private]

The tag indicating the current state of the object.

We use this to compare against the comparison_tag in the HasChanged method. This member is increased every time the object changes.

Definition at line 138 of file IpTaggedObject.hpp.

The index indicating the cache priority for this TaggedObject.

If a result that depended on this TaggedObject is cached, it will be cached with this priority

Definition at line 145 of file IpTaggedObject.hpp.


The documentation for this class was generated from the following file:
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Defines

Generated on 9 Aug 2013 for Ipopt by  doxygen 1.6.1