OOF2: The Manual

FieldIndex
	Indices and Iterators

Name

FieldIndex — Base class for index objects

Synopses

C++ Synopsis

#include "engine/fieldindex.h"

class FieldIndex {
  virtual int integer() const;
  
          operator int() const;
  virtual bool in_plane() const;
  virtual FieldIndex* clone() const;
}

Python Synopsis

from ooflib.SWIG.engine.fieldindex import FieldIndex

class FieldIndex:
  def integer(self)
  def in_plane(self)

Subclasses

Source Files

SRC/engine/fieldindex.h: C++ header
SRC/engine/fieldindex.C: C++ source code
SRC/engine/fieldindex.swg: SWIG source code
SRC/engine/fieldindex.spy: Python code included in the SWIG output

Description

FieldIndex is the abstract base class for classes which refer to the components of multi-dimensional Fields, Fluxes, Equations, and OutputVals. The different subclasses refer to components of scalars, vectors, and tensors.

In C++, a FieldIndex is usually obtained by looping over a Field or Flux's components, or calling their getIndex method. In the first case, the returned index is automatically wrapped in an IndexP, which handles the deallocation of the FieldIndex. In the second, the returned FieldIndex pointer needs to either be explicitly deallocated or manually wrapped in an IndexP.

In Python there is no need for the IndexP class. Whenever a FieldIndex object is returned from a C++ function to Python, it is converted into an object of the appropriate derived class. Thus, in Python every FieldIndex object is explicitly a ScalarFieldIndex, VectorFieldIndex, or other subclass of FieldIndex.

Methods

`virtual int integer() const`

Every kind of FieldIndex has a canonical ordering of the indices that it represents. For example, a VectorFieldIndex takes the values x, y, z in that order, and a SymTensorIndex takes the values xx, yy, zz, yz, xz, xy, in that order. FieldIndex::integer() returns the current value's position in the canonical list.

integer() is used whenever an FieldIndex needs to determine a position in a Python list, C++ std::vector, or other linear storage structure. It may also be used in some situations where functions weren't designed to accept the more abstract FieldIndex or IndexP objects, for whatever reason.

`operator int() const`

operator int converts a FieldIndex to an integer by calling FieldIndex::integer(). It allows a FieldIndex to be used as an argument to a C++ function that is expecting a integer.

`virtual bool in_plane() const`

in_plane indicates whether or not the FieldIndex refers to an in-plane or out-of-plane index. For vectors, x and y are in-plane and z is out-of-plane. For tensors, any set of indices containing a z is out-of-plane.

`virtual FieldIndex* clone() const`

A FieldIndex obtained by looping over Components is transient, and will be deleted when the iteration is complete. If it's necessary to retain a FieldIndex, call clone() to create a new one. It is the caller's responsibility to delete the returned pointer.


Indices and Iterators		IndexP