What's behind the scenes of the view (...) function?

General Usage
, ,
2

You can see the difference between getindex and view when mutating an element of b:

julia> a = [1, 2, 3];

julia> b = a[1:2]
2-element Vector{Int64}:
 1
 2

julia> c = view(a, 1:2)
2-element view(::Vector{Int64}, 1:2) with eltype Int64:
 1
 2

julia> b[1] = 4
4

julia> a  # Data in a is unchanged
3-element Vector{Int64}:
 1
 2
 3

julia> c[1] = 4
4

julia> a  # Data in a has changed as well
3-element Vector{Int64}:
 4
 2
 3

Thus, getindex will take the values from the slice and copy it into a new array. In contrast, view just wraps the original array and indexes into it. Thereby, getindex is safer to use, i.e., as it cannot change the data it has been taken from, whereas view is faster as it does not need to copy.