Creating Custom Functions Using Name Conventions¶
We recommend developing custom functions using annotations. However, it is also possible to do it following certain conventions for the name of the class and its methods.
In order to make a Java class recognizable as a custom function, the name of the class has to match the following rules:
<FunctionName>VdpFunctionfor condition functions
<FunctionName>VdpAggregateFunctionfor aggregation functions
These conventions are case sensitive. That means that the name of
the class has to be like
function1VdpFunction and not
This way a Java class named
Concat_SampleVdpFunction will be
interpreted as a condition function named
Concat_Sample; and a class
Group_Concat_SampleVdpAggregateFunction, as an aggregate
All Java methods implementing the function signatures must have the name
execute. The signature associated with each method will be extracted
from its method parameters.
For example a class named
Concat_SampleVdpFunction with a method
execute(valueA:String, valueB:String):String will generate the
The way to define an arity n in a custom function is with an array as
the last parameter in the method. I.e. a class
Concat_SampleVdpFunction with a method declared as
public String execute(String  inputs).
A custom function has to define a method named
with the same parameters as the associated
execute method if:
- The return type of the function is an array or a register.
- Or, the return type of the function depends on the type of the input parameters.
See the section Custom Function Return Type for more details about this method.