# Can a type be declared as a subtype of my abstract type and Tuple?

**URL:** https://discourse.julialang.org/t/can-a-type-be-declared-as-a-subtype-of-my-abstract-type-and-tuple/73867
**Category:** General Usage
**Tags:** type, tuple
**Created:** [December 31, 2021, 3:08pm UTC](https://discourse.julialang.org/t/can-a-type-be-declared-as-a-subtype-of-my-abstract-type-and-tuple/73867 "2021-12-31T15:08:52Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![Thomas](https://avatars.discourse-cdn.com/v4/letter/t/e36b37/32.png) [@Thomas](https://discourse.julialang.org/u/Thomas)
#### Post date: [December 31, 2021, 3:08pm UTC](https://discourse.julialang.org/t/can-a-type-be-declared-as-a-subtype-of-my-abstract-type-and-tuple/73867/1 "2021-12-31T15:08:52Z")

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Say I have `abstract type Custom end`, how can I declare a tuple-like type that is both `<:Tuple` and `<:Custom` so that methods of `Tuple` works on `Custom`. Note that I would like vararg-tuple if possible. Thanks!

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### Author: ![DNF](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/dnf/32/10191_2.png) [@DNF](https://discourse.julialang.org/u/DNF)
#### Post date: [December 31, 2021, 7:19pm UTC](https://discourse.julialang.org/t/can-a-type-be-declared-as-a-subtype-of-my-abstract-type-and-tuple/73867/2 "2021-12-31T19:19:06Z")

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That is not possible. Multiple inheritance is not available in Julia, and also you cannot subtype concrete types like `Tuple`.