add similar_type

Author: mateuszbaran

Project.toml

@@ -1,6 +1,6 @@
 name = "StaticArraysCore"
 uuid = "1e83bf80-4336-4d27-bf5d-d5a4f845583c"
-version = "1.0.1"
+version = "1.1.0"
 
 [compat]
 julia = "1.6"

src/StaticArraysCore.jl

@@ -269,4 +269,26 @@ const SizedVector{S,T} = SizedArray{Tuple{S},T,1,1}
 
 const SizedMatrix{S1,S2,T} = SizedArray{Tuple{S1,S2},T,2}
 
+"""
+    similar_type(static_array)
+    similar_type(static_array, T)
+    similar_type(array, ::Size)
+    similar_type(array, T, ::Size)
+
+Returns a constructor for a statically-sized array similar to the input array
+(or type) `static_array`/`array`, optionally with different element type `T` or size
+`Size`. If the input `array` is not a `StaticArray` then the `Size` is mandatory.
+
+This differs from `similar()` in that the resulting array type may not be
+mutable (or define `setindex!()`), and therefore the returned type may need to
+be *constructed* with its data.
+
+Note that the (optional) size *must* be specified as a static `Size` object (so the compiler
+can infer the result statically).
+
+New types should define the signature `similar_type(::Type{A},::Type{T},::Size{S}) where {A<:MyType,T,S}`
+if they wish to overload the default behavior.
+"""
+function similar_type end
+
 end # module