# Modifying vector in an immutable
**URL:** https://discourse.julialang.org/t/modifying-vector-in-an-immutable/1339
**Category:** General Usage
**Tags:** question
**Created:** [January 7, 2017, 1:41pm UTC](https://discourse.julialang.org/t/modifying-vector-in-an-immutable/1339 "2017-01-07T13:41:06Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)
#### Post date: [January 7, 2017, 1:41pm UTC](https://discourse.julialang.org/t/modifying-vector-in-an-immutable/1339/1 "2017-01-07T13:41:06Z")
When an `immutable` has a `Vector` field, is it allowed to modify that using `!` functions ([like these](http://docs.julialang.org/en/stable/stdlib/collections/#dequeues))? My understanding is that even if the underlying memory is remapped (eg because the vector grows or shrinks too much), it is still the “same” vector, so it is OK. MWE:
```julia
immutable Foo
v::Vector
end
foo = Foo([])
push!(foo.v, 1)
```
---
### Author:  [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)
#### Post date: [January 7, 2017, 1:53pm UTC](https://discourse.julialang.org/t/modifying-vector-in-an-immutable/1339/2 "2017-01-07T13:53:23Z")
It is still the same julia object. This is perfectly fine.
---
### Author:  [@dpsanders](https://discourse.julialang.org/u/dpsanders)
#### Post date: [January 7, 2017, 4:44pm UTC](https://discourse.julialang.org/t/modifying-vector-in-an-immutable/1339/3 "2017-01-07T16:44:24Z")
Note that you (almost) always want to strictly type fields in a type definition:
```julia
immutable Foo
v::Vector{Float64}
end
```
or parametrically:
```julia
immutable Foo{T}
v::Vector{T}
end
```
---
### Author:  [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)
#### Post date: [January 7, 2017, 5:49pm UTC](https://discourse.julialang.org/t/modifying-vector-in-an-immutable/1339/4 "2017-01-07T17:49:26Z")
Definitely — I was just keeping the example minimal.