# Index type ("ElementIdentifier") of \`itk::VectorContainer\` is now \`itk::SizeValueType\` by default, please check!

**URL:** <https://discourse.itk.org/t/index-type-elementidentifier-of-itk-vectorcontainer-is-now-itk-sizevaluetype-by-default-please-check/7263>\
**Category:** Engineering\
**Created:** [October 17, 2024, 11:49am UTC](https://discourse.itk.org/t/index-type-elementidentifier-of-itk-vectorcontainer-is-now-itk-sizevaluetype-by-default-please-check/7263 "2024-10-17T11:49:11Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Niels\_Dekker](https://discourse.itk.org/letter_avatar_proxy/v4/letter/n/9d8465/32.png) [@Niels\_Dekker](https://discourse.itk.org/u/Niels_Dekker)\
**Post date:** [October 17, 2024, 11:49am UTC](https://discourse.itk.org/t/index-type-elementidentifier-of-itk-vectorcontainer-is-now-itk-sizevaluetype-by-default-please-check/7263/1 "2024-10-17T11:49:11Z")

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From commit [ENH: Make index type of VectorContainer SizeValueType by default · InsightSoftwareConsortium/ITK@4b5e5be · GitHub](https://github.com/InsightSoftwareConsortium/ITK/commit/4b5e5bea934d2540c8f0013dff889d1b812b3bd9) (merged to the “master” branch for ITK 6.0), it is no longer necessary to explicitly specify the index type (“ElementIdentifier”) of an `itk::VectorContainer`. The index type is now `itk::SizeValueType` by default. So for example, in user code, `itk::VectorContainer<itk::SizeValueType, float>` may be replaced with `itk::VectorContainer<float>`.

With the following pull request, I’m proposing to remove those explicit template arguments from a few VectorContainer use cases in the ITK source tree itself. Please have a look:

> <https://github.com/InsightSoftwareConsortium/ITK/pull/4879>
>
> \- Following pull request #4856 commit edae0bcd6e0dcf679abd08d77792d0867c693878
> …
> Note that this pull request should not affect the API or the ABI of ITK in any way. 😇

If you like this pull request, please approve it 👍

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**Author:** ![dzenanz](https://discourse.itk.org/user_avatar/discourse.itk.org/dzenanz/32/1093_2.png) [@dzenanz](https://discourse.itk.org/u/dzenanz)\
**Post date:** [October 17, 2024, 2:14pm UTC](https://discourse.itk.org/t/index-type-elementidentifier-of-itk-vectorcontainer-is-now-itk-sizevaluetype-by-default-please-check/7263/2 "2024-10-17T14:14:52Z")

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It would be good if someone else besides me took a look.