if i create a new object type and its parameters as well, then i want to add an event handler for this parameter, so if the parameter is modified/changed this handler will call a function.
kind like –> onchange().
the goal is to make a filter , so if someone change the value too high , it will be automatically cut down to max value allowed. it's similar to ‘clamp’, but this time i hope i can make a ‘realtime’ filter.

is it possible or not?

clay~

try using your parameter's Callback field(type properties/parameters), any commands entered here will be executed when the parameter's value changes

thx lucap,
it works..but why it's executed twice?
i tested by putting ‘message test’ in callback, and when i change the value, the message is displayed twice, why?
what if i want to apply this to built-in op type, the parameter is locked, there's no callback param available. can i do this?

clay~