Package org.qdl_lang.extensions.examples.basic

Class ExtrinsicFunction

java.lang.Object

org.qdl_lang.extensions.examples.basic.ExtrinsicFunction

All Implemented Interfaces:

Serializable, QDLFunction

public class ExtrinsicFunction
extends Object
implements QDLFunction

An basic of an extrinsic (aka global, static in other languages) function. This function will be treated like any other function. It is available everywhere in the workspace.

When creating one, remember that only things that truly need to be accessible the same everywhere should be made extrinsic.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static String	EX_NAME

Constructor Summary

Constructors

Constructor	Description
ExtrinsicFunction()

Method Summary

Modifier and Type	Method	Description
Object	evaluate(Object[] objects, State state)	The method that is invoked by QDL that is the function.
int[]	getArgCount()	The contract is that when QDL invokes this method, it will faithfully give all of the arguments as an array of Objects.
List<String>	getDocumentation(int argCount)	Return documentation to be displayed in the workspace.
String	getName()	The name of this function as you want it invoked in QDL.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

EX_NAME

public static String EX_NAME

Constructor Detail

ExtrinsicFunction

public ExtrinsicFunction()

Method Detail

getName

public String getName()

Description copied from interface: QDLFunction

The name of this function as you want it invoked in QDL. This will be what the function is called in the workspace.

Specified by:

getName in interface QDLFunction

Returns:

getArgCount

public int[] getArgCount()

Description copied from interface: QDLFunction

The contract is that when QDL invokes this method, it will faithfully give all of the arguments as an array of Objects. Overloading is not possible in QDL (it is weakly typed) except by argument count, so if this is called "foo" and you have versions with 3 and 4 arguments, then f(a,b,c) would be executed with the arguments passed. To achieve overloading for Java methods, have the number of arguments this accepts as the elements of the array. So if this has a value of [1,2,3] then this function will be invoked if called with 1, 2 or 3 arguments and an error by the QDL runtime engine will be raised, if, say, 4 are passed.

Specified by:

getArgCount in interface QDLFunction

Returns:

evaluate

public Object evaluate(Object[] objects,
                       State state)
                throws Throwable

Description copied from interface: QDLFunction

The method that is invoked by QDL that is the function. It will have the arguments already evaluated and put in to the array of objects. It is up to you to do any checking you see fit. State is supplied if needed.

Specified by:

evaluate in interface QDLFunction

Returns:

Throws:

Throwable

getDocumentation

public List<String> getDocumentation(int argCount)

Description copied from interface: QDLFunction

Return documentation to be displayed in the workspace. Short version displays the first line (element of the list) so make sure that is informative. The long version should contain details of use. Best practice is that have a succinct one line description for each arg count and a body that explains the usage more fully.

Specified by:

getDocumentation in interface QDLFunction

Returns: