Data Processing is used with EASAPs to process and manipulate data. The data to be processed can be data entered by users or data read from a file. Some examples of situations where processing data will be useful are:
Any object that has a value associated with it will be one of two data types: a scalar or a list. A scalar object is characterized by having only a single value. List objects, on the other hand, can have one or more values. Also, a list object can have zero size and have no values defined. Scalar and list objects are identified on the EASAP tree by the color of their name. Scalar objects are colored blue, while list objects are colored green. The types of data produced by the available data processing tools under the Data Processing object are also divided between scalar and list. In fact, there are two sub-branches beneath every Data Processing object called SCALAR and LIST. All data processing objects that produce scalars are found under SCALAR, while all data processing objects that produce lists are found under LIST. The following sections will provide detailed descriptions of all the data processing objects available under both the SCALAR and LIST sub-branches.
The majority of objects that have a value associated with them, including all those under the Data Processing and those described in GUI of an EASAP are evaluated automatically on an as needed basis and the Author does not control when evaluation happens. Usually, automatic evaluation of dependents is exactly what an Author wants. However, there are times when it is beneficial to be able to control exactly when the value of an object is evaluated. This is typically done through action objects located either in the Event Processing or the Processes branch. Objects defined in these action objects are known as explicit objects.