CANCEL operator

The CANCEL operator creates an action that cancels changes in the current session.

Syntax

CANCEL [NESTED [nestedPropertySelector] [CLASSES]]

where nestedPropertySelector has one of the following forms:

LOCAL
(propertyId1, ..., propertyIdN)

Description

The CANCEL operator creates an action that cancels changes in the current session. By specifying the keyword NESTED you can specify local properties whose changes are not dropped when cancelling the changes.

Parameters

• NESTED

  Optional keyword after which you can specify which local properties preserve their changes after the CANCEL operator is executed. By itself, with neither LOCAL nor a property list, it has no effect on the operator.

• LOCAL

  Keyword. If specified after NESTED, all local properties preserve their changes after the CANCEL operator is executed.

• propertyId1, ..., propertyIdN

  Non-empty list of local properties, specified after NESTED in parentheses. Each list element is a property ID. The local properties specified in the list will preserve their changes after the operator is executed.

• CLASSES

  Keyword. Can be written, but has no effect on the CANCEL operator.

Examples

CLASS Sku;
in = DATA LOCAL BOOLEAN (Sku);

// bare cancel — drops every change accumulated in the current session
dropChanges()  { CANCEL; }

// cancel that preserves a specific local property
dropChangesKeepIn()  {
    CANCEL NESTED (in[Sku]); // cancel all changes except the `in[Sku]` property
}

// cancel that preserves all local properties
dropChangesKeepAll()  { CANCEL NESTED LOCAL; }