Recommend to use tuples to scalarize items in broadcast expressions (#…

…35591)

* don't wrap `UInt8` in a tuple

* Recommend to use tuples to scalarize an item.

* Don't recommend to use Ref for scalarizing

* Update arrays.md

* Update refpointer.jl

* add Matt's recommendation

* remove whitespace

base/refpointer.jl

@@ -20,8 +20,8 @@ There is no invalid (NULL) `Ref` in Julia, but a `C_NULL` instance of `Ptr` can
 a `ccall` Ref argument.
 
 # Use in broadcasting
+`Ref` is sometimes used in broadcasting in order to treat the referenced values as a scalar:
 
-Broadcasting with `Ref(x)` treats `x` as a scalar:
 ```jldoctest
 julia> isa.(Ref([1,2,3]), [Array, Dict, Int])
 3-element BitArray{1}:

doc/src/manual/arrays.md

@@ -933,7 +933,7 @@ julia> convert.(Float32, [1, 2])
  1.0
  2.0
 
-julia> ceil.((UInt8,), [1.2 3.4; 5.6 6.7])
+julia> ceil.(UInt8, [1.2 3.4; 5.6 6.7])
 2×2 Array{UInt8,2}:
  0x02  0x04
  0x06  0x07
@@ -945,6 +945,17 @@ julia> string.(1:3, ". ", ["First", "Second", "Third"])
  "3. Third"
 ```
 
+Sometimes, you want a container (like an array) that would normally participate in broadcast to be "protected"
+from broadcast's behavior of iterating over all of its elements. By placing it inside another container
+(like a single element [`Tuple`](@ref)) broadcast will treat it as a single value.
+```jldoctest
+julia> ([1, 2, 3], [4, 5, 6]) .+ ([1, 2, 3],)
+([2, 4, 6], [5, 7, 9])
+
+julia> ([1, 2, 3], [4, 5, 6]) .+ tuple([1, 2, 3])
+([2, 4, 6], [5, 7, 9])
+```
+
 ## Implementation
 
 The base array type in Julia is the abstract type [`AbstractArray{T,N}`](@ref). It is parameterized by