# BoundVariableExpression activation

**URL:** <https://forum.inductiveautomation.com/t/boundvariableexpression-activation/45282>\
**Category:** Module Development\
**Created:** [April 5, 2021, 8:54pm UTC](https://forum.inductiveautomation.com/t/boundvariableexpression-activation/45282 "2021-04-05T20:54:33Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [April 5, 2021, 10:11pm UTC](https://forum.inductiveautomation.com/t/boundvariableexpression-activation/45282/2 "2021-04-05T22:11:47Z")

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Please re-read my comment in this other thread--I believe you've misunderstood:

> [@Add binding and scripting to vision component](http://forum.inductiveautomation.com/t/add-binding-and-scripting-to-vision-component/44650/4):
>
> Some implementation notes for built-in functionality: The designer’s mouse events, key events, and propertyChange listeners simply implement the corresponding java listeners. Your components would implement built-in functionality directly in java, and add them to the component either at creation or in the startup method. Property bindings you wish to implement would simply be listeners of the appropriate types for all of the relevant source data. If the source data is on a different comp…

` ************************** `

> [@damien.boissat](#):
>
> Do you have any idea how to do this?

You are struggling because components are not intended to be making their own bindings. For built-in functionality, your components should be doing the equivalent with runtime listeners. Your component classes should have nested classes implementing the appropriate listener types and overriding the event message methods to distribute the arriving data. This is how **internal** bindings are constructed.

Property Adapters and related bindings are how the **designer** adds _ **user-supplied** _ functionality at _ **configuration** _ time.

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