Optional variable (with default value) in custom function

Question

Is it possible to use an optional variable (value2) like

...
@qgsfunction(args='auto', group='Custom')
def my_test(value1, value2=True, feature, parent)
....

in a custom function? Using QGIS 3.8

...like

Answer 1

Not sure of a direct way but there is the handlesnull flag which when set to true would let you input NULL as a parameter value.

...
@qgsfunction(args='auto', group='Custom', handlesnull=True)
def my_test(value1, value2, feature, parent):
...

You might want to include some logic in your code to determine what happens when a parameter value is NULL.