More about function rules
 

Where functions can be called

Functions can be called within expressions and in Java code. The syntax differs slightly.

Deleting all functions in a library

You can delete a function rule with Delete or (if checked out to you) Discard.

When you delete a function rule, PRPC does not check to see whether the function is referenced in other rules (such as expressions or alias function rules). If the function may be called somewhere, open the Library form for the library to which this function rule belongs and click  Generate Library   to force recompilation of the library. At runtime, any references to the deleted function fail.

When you delete a library rule with Delete, the system also deletes all function rules in the library (for all RuleSet Versions for the RuleSet), and deletes the assembled and Java-compiled functions in the library. In a multinode cluster, if you delete a library rule, the system pulse processing performed by the Pega-RULES agent on other nodes deletes the compiled Java and CLASS files from disk. PROJ-338 SDAS 2/27/07.

Syntax for calling functions

To call a function as part of an expression, use syntax similar to:

@(Pega-RULES:DateTime).getCurrentTimeStamp();

where Pega-RULES is the name of the RuleSet and DateTime is the name of the library.

Some functions accept parameters. Usually, when you call a function from within an activity, refer to the activity using Java's this keyword.

@(Pega-RULES:Default).GetInstanceHandle("pageName", this);

Calling functions from Java

You can incorporate custom Java in rules of these six rule types:

• Activities, by using the Java instruction or the Property-Set method
• Data transforms
• HTML rules, using the Java directive, and other stream-based rules (XML, correspondence, HTML fragments, correspondence fragments, harness, sections, and flow actions)
• Edit Input rules
• Edit Validate rules
• Validate

Functions when compiled extend the Java class:

com.pegarules.generated.myruleset_mylibrary

where the RuleSet name and library name are converted to lowercase. To call a function from within Java, use the following syntax:

result =
com.pegarules.generated.myruleset_mylibrary.MyFunction( params )

using the exact case for the function name.

Calling functions with side effects

To call a function primarily for its side effects (rather than to return a value), you can use the Property-Set method and place the result in a local variable. (Make sure the function returns a non-void value, such as a Boolean).

On the left-hand side (destination) of the Property-Set, enter Local.myLocalBoolean. On the right-hand side, use the call syntax above.

Security

If your application rulesets contain utility function rules, run the Rule Security Analyzer before locking a ruleset version, to look for possible security issues.

Using function alias rules to simplify decision rules

If your application includes decision table, decision tree, map value, constraints, or Declare Expression rules that are to be maintained by users or less technical staff, you can define function alias rules to simplify their work and present choices in application-centric terms. See About Function Alias rules.

How functions appear in generated Java

In the generated Java, function calls look like:

pega_rules_default.getCurrentTimeStamp();

How to recompile all libraries at once

When necessary, you can force extraction and recompilation of all functions in all libraries (on the current node):

1. Stop the application server.
2. Delete the text file PegaRULES_Extract_Marker.txt file.
3. Restart the application server.

This adds an INFO line to the Pega log noting the re-extraction.

Advanced note: helper methods

Your Java code can contain helper methods that support the function rule computations. Define an inner class and define all the helper methods inside it. From the Java code outside this class you can create an instance of this class and can access the methods of this class. The inner class methods are not exposed.

For an example, review the Java tab of the standard edit input rule named PartialDate.

Advanced note: Function overloading

You can define two or more function rules in one library with the same name, RuleSet, and version if the signatures are different. When Java code (or an expression) includes a call to the function, PRPC uses the number, position, and data types of function parameters to determine which rule to execute.

The signature consists of the function name plus the types and names of the parameters in order.

Advanced note: Attributes of parameters

Each parameter of a function rule contains the following additional attributes. These are available for documentation purposes only; they do not affect Java code generation or other processing.

• pyUsage, a description of what the parameter is and how it is used (for JavaDocs)
• pyDataType, available to document the PRPC data type of the parameter if the corresponding Java data type is String or ClipboardProperty
• pyPageClass, if pyDataType is Page, can document the class (or superclass) of the page
• pyMode, can document whether the parameter is an input or output value.

Advanced note: Return values

The return value of a function contains the following additional attributes:

• pyUsage, a description of the return value (for documentation such as JavaDocs)
• pyDataType, the PRPC data type of the return value if the Java data type is String or ClipboardProperty
• pyPageClass, if pyType is Page, optionally identifies the class (or superclass) of the page
• The pyIntrinsic, reserved for future use to support efficient inline code generation.

Advanced note: Other properties of function rules

Function rules contain attributes and capabilities including:

• pyImports, a list of packages to be imported into the library.
• pyThrows, a list of Java exceptions thrown by the function.
• pyInline, a hint to Java translators of when this function can be included within a rules assembly class: Never, Always, If appropriate.
• pyIntrinsic, a hint to Java translators that if the translator has its own optimized implementation of a function with the same name, it may use that version: true or false.
• pyMethodFrom, reserved for future use.

Advanced note: Java EE support

When executing in the enterprise tier of a Java EE application server, applications cannot directly read from or write to the server file system. To minimize maintenance issues with custom Java code you write that may run in Java EE enterprise mode, do not use native java.io routines. Instead, use the Virtual File Interface (part of the Public API), which provides similar methods with the same names.
For Web tier installations, the Virtual File Interface methods merely call the corresponding native Java methods.

	Virtual File Interface
	About Library rules Using Java in activity steps How to set up a Java development environment
	Atlas — Standard functions

About Function rules