Task Variables

Task variables are visible to all functions within a task. They provide a means of sharing common data between more than one function. Task variables are similar to function parameters in that they are composed of a name, type and accessibility descriptor. The types supported by task variables are (and must remain) identical to those supported by a task function. Task variables also support optional descriptions. However, unlike function parameters, a task variable cannot be marked as optional. Advantages of Task Variables are:

• Preservation of task-centric values - Data that is common to the entire task, and more than one function needs to use its contents, are candidates for elevation to a task variable. An example could be a variable to indicate whether or not the task is being run by particular way, or if the task is in “normal” or “error recovery” mode.

• Can be used as a “named constant” - In AWE, a constant is defined at the system level. However, there are situations where a value is meant to be preserved throughout the lifetime of a task, regardless of function or external task, but not dictated by the system configuration. A Task Variable can accomplish this, optionally with the read-only option set.

• Provides consistent and predictable access with external tasks - When an external task is called, for example by using the Start Task action, the Task Variables public variables of both tasks are merged together and accessible by both tasks. This allows the creation of, for example, utility tasks that share common data (such as a company name, version number, etc.) See the “External Tasks” section for more details.

• Allows information-protection and controls access by external tasks - This can be accomplished by using the accessibility options of a task variable. They control which task variables are merged into a parent task or accessible through a task object.

NOTE: Task variables are different from local variables which are created using the Create Variable action.

Sub-Tasks

Sub-tasks are task files that are executed within another task by using the Start Task action. In this situation, the parent task’s (i.e. the task executing the Start Task step) public functions, public extended functions, public task variables, and any local variables marked as public created up to point where the Start Task step is encountered, are accessible to the sub-task. All other variables and functions are not accessible to the sub-task. Conversely, because the Start Task action is a synchronous operation, the sub-task’s public functions and public task variables are not accessible from the parent task. This is fully backward compatible with previous versions of AWE, since in the past there was only one “function” (what is now called “main”), no task variables, and all (local) variables and extended functions were considered public.

Creating and Managing Task Variables

Task variables are created and presented in a separate panel located on the Steps pane.

To create a new Task Variable:

1. In the Steps pane, click the icon to open the Task Functions/Variables table. This expands the panel where you can set specific parameters.

2. Click Add. The Task Variable dialog box appears.

3. Specify the variable name, variable type, access type value, and optional description, then click OK.

4. Click the new variable icon to collapse the panel.

To edit an existing Task Variable:

1. In the Steps pane, open the Task Functions/Variables table.

2. Select the variable you want to edit and click the Edit button.

3. Make the desired modifications then click OK when finished. Reflected changed appear in the main panel.

To delete an existing Task Variable:

1. In the Steps pane, open the Task Functions/Variables table.

2. Select the variable you want to delete and click the Remove button.

The following table describes the parameters available during task variable creation/modification.

See Also

Variables

Task Functions

Datasets

Arrays

Expressions

Create Variable Action