EDOBE XDOM PMML Bedienungsanleitung PDF herunterladen (Seite 87)

of a class, this creates and exports a regular C function (with a long,

ugly name including the class name) that creates an instance of that

class. For example,

CNKProcRandomReader.cpp contains the line:

CNK_DEFINE_ACCESSIBLE_CLASS(CNKProcRandomReader)

The init() Method

If a subclass of

CNKProc redefines the init() method, the redefined

init() method should start by calling its superclass method:

CNKProc::init().

Most

init() methods should check that the CNKProc has the right

number of input and output

CNKBufs. This is most easily done by

calling

CNKProc::checkBufs.

The

init() method performs any initialization that the object

requires, based on the values of any properties that have been set.

Some of these properties may be common to all

CNKProc objects, such

as the input and output bufs (accessed with

getNumInputs, etc), and

the number of rows (accessed with

getNumRows, etc). Some properties

may be specific to this particular class. For example, a file reader

object would have methods for setting properties such as the file

name, file type, etc. Within the

init() method, these properties are

used to initialize any internal data structures required to execute the

object.

Although the main data storage mechanism for the TIBCO Spotfire

Pipeline is the

CNKBuf data structure, it is also possible to allocate and

use storage within a given

CNKProc object. For example, a model-

building

CNKProc may allocate internal storage for accumulating and

processing the data being modeled. If these internal data structures

are of a fixed size, they can be specified as part of the

CNKProc

subclass instance variables. If the internal data structures can have

different sizes depending on the number of columns and rows of the

inputs, then they could be allocated dynamically, within the

init()

method. In this case, the dynamically-allocated data should be

released if the

init() method is called a second time, and it should be

released in the class destructor.

The execute() Method

The

execute() method needs to manage its inputs and outputs, as

well as actually performing the data manipulation operation. More

explicitly, the

execute() method should perform the following steps:

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