# TBB and 2.21

**URL:** <https://discourse.mc-stan.org/t/tbb-and-2-21/11179>\
**Category:** Developers\
**Created:** [September 30, 2019, 9:29am UTC](https://discourse.mc-stan.org/t/tbb-and-2-21/11179 "2019-09-30T09:29:02Z")\
**Posts on this page:** 1\
**Showing post:** 8

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**Author:** ![rok\_cesnovar](https://avatars.discourse-cdn.com/v4/letter/r/7bcc69/32.png) [@rok\_cesnovar](https://discourse.mc-stan.org/u/rok_cesnovar)\
**Post date:** [September 30, 2019, 8:59pm UTC](https://discourse.mc-stan.org/t/tbb-and-2-21/11179/8 "2019-09-30T20:59:05Z")

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I will take a look tomorrow before noon. Too little focus to do it thoroughly right now.

Judging just from your post it seems its what we agreed at the [Math meeting](https://discourse.mc-stan.org/t/monthly-math-development-meeting-9-19-2019-10am/11003/7) (discussion around a helper function).

EDIT:

Quick comment not on the general design: I would prefer not using `getenv`. In this case I would prefer ifdefing and just assigning a default value when the define is not present. That way you also dont need to do the lexical parse as this becomes a compile time error.

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_[View the full topic](https://discourse.mc-stan.org/t/tbb-and-2-21/11179)._