# URCap API Expression Builder

**URL:** <https://forum.universal-robots.com/t/urcap-api-expression-builder/13767>\
**Category:** Report a Bug\
**Created:** [April 20, 2021, 7:25am UTC](https://forum.universal-robots.com/t/urcap-api-expression-builder/13767 "2021-04-20T07:25:26Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![anon14470933](https://avatars.discourse-cdn.com/v4/letter/a/2bfe46/32.png) [@anon14470933](https://forum.universal-robots.com/u/anon14470933)\
**Post date:** [April 20, 2021, 7:25am UTC](https://forum.universal-robots.com/t/urcap-api-expression-builder/13767/1 "2021-04-20T07:25:26Z")

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I’m building a URCap in which I have a program node. This program node creates a child node consistent of an assignment node. In this assignment I create an expression using the ExpressionBuilder that looks similar to “test.helloworld()” (please note the dot between the “test” and the “helloworld()” method call, however the expression validator will not accept that I programatically create an assignment with a dot inside it. However from polyscope it is (obviously) allowed from user input. Could you please update the validator to allow dots inside Expressions?

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**Author:** ![Ebbe](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.universal-robots.com/ebbe/32/1413_2.png) [@Ebbe](https://forum.universal-robots.com/u/Ebbe)\
**Post date:** [April 21, 2021, 12:20pm UTC](https://forum.universal-robots.com/t/urcap-api-expression-builder/13767/2 "2021-04-21T12:20:13Z")

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Hi @anon14470933

Thank you for you feedback. I see the issue and will report it. For the meantime I will suggest you make a workaround where you add the following URScrip to you preamble

```auto
def test_helloworld():
  return test.helloworld()
end

```

and then create an expression with the function.

Ebbe

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<div class="post-metadata">

**Author:** ![anon14470933](https://avatars.discourse-cdn.com/v4/letter/a/2bfe46/32.png) [@anon14470933](https://forum.universal-robots.com/u/anon14470933)\
**Post date:** [April 22, 2021, 6:32am UTC](https://forum.universal-robots.com/t/urcap-api-expression-builder/13767/3 "2021-04-22T06:32:14Z")

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Thanks 🙂 👍 right now I’m just relying on the user to change ‘+’ to ‘.’ but might change it to your solution at a later point.

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**Author:** ![system](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.universal-robots.com/system/32/1_2.png) [@system](https://forum.universal-robots.com/u/system)\
**Post date:** [April 24, 2021, 6:32am UTC](https://forum.universal-robots.com/t/urcap-api-expression-builder/13767/4 "2021-04-24T06:32:54Z")

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