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Recommend to use tuples to scalarize items in broadcast expressions #35591

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Merged
merged 7 commits into from
Apr 29, 2020
Merged

Recommend to use tuples to scalarize items in broadcast expressions #35591

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8d55fa5
don't wrap `UInt8` in a tuple
MasonProtter Apr 24, 2020
9159a5c
Recommend to use tuples to scalarize an item.
MasonProtter Apr 24, 2020
2aa899e
Don't recommend to use Ref for scalarizing
MasonProtter Apr 24, 2020
17d984f
Update arrays.md
MasonProtter Apr 28, 2020
f2d92c5
Update refpointer.jl
MasonProtter Apr 28, 2020
329c1e4
add Matt's recommendation
MasonProtter Apr 28, 2020
1fc0325
remove whitespace
MasonProtter Apr 29, 2020
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2 changes: 1 addition & 1 deletion base/refpointer.jl
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Expand Up @@ -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}:
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13 changes: 12 additions & 1 deletion doc/src/manual/arrays.md
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Expand Up @@ -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
Expand All @@ -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
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