Type-stability in polynomial space union (#293)

* Type-stability in polynomial space union

* Bump version to v0.6.43

Author: jishnub

Project.toml

@@ -1,6 +1,6 @@
 name = "ApproxFunOrthogonalPolynomials"
 uuid = "b70543e2-c0d9-56b8-a290-0d4d6d4de211"
-version = "0.6.42"
+version = "0.6.43"
 
 [deps]
 ApproxFunBase = "fbd15aa5-315a-5a7d-a8a4-24992e37be05"

src/Spaces/PolynomialSpace.jl

@@ -322,11 +322,11 @@ end
 
 
 
-## All polynomial spaces can be converted provided spaces match
+## All polynomial spaces can be converted provided domains match
 
-isconvertible(a::PolynomialSpace,b::PolynomialSpace) = domain(a) == domain(b)
-union_rule(a::PolynomialSpace{D},b::PolynomialSpace{D}) where {D} =
-    domainscompatible(a,b) ? (a < b ? a : b) : NoSpace()   # the union of two polys is always a poly
+isconvertible(a::PolynomialSpace, b::PolynomialSpace) = domain(a) == domain(b)
+union_rule(a::PolynomialSpace{D}, b::PolynomialSpace{D}) where {D} =
+    conversion_type(a, b)
 
 
 

test/UltrasphericalTest.jl

@@ -15,6 +15,9 @@ include("testutils.jl")
 @verbose @testset "Ultraspherical" begin
     @testset "promotion" begin
         @inferred (() -> [Ultraspherical(1), Ultraspherical(2.0)])()
+        f = Fun(Chebyshev())
+        g = Fun(Ultraspherical(1))
+        @test @inferred(f + g) ≈ 2f
     end
     @testset "identity fun" begin
         for d in (ChebyshevInterval(), 3..4, Segment(2, 5), Segment(1, 4im)), order in (1, 2, 0.5)