Improve and test conversions

Author: David Widmann

src/symbolic_dimensions.jl

@@ -71,27 +71,23 @@ end
 function Base.convert(::Type{Quantity{T,SymbolicDimensions}}, q::Quantity{<:Any,<:Dimensions}) where {T}
     return convert(Quantity{T,SymbolicDimensions{DEFAULT_DIM_BASE_TYPE}}, q)
 end
-function Base.convert(::Type{Q}, q::Quantity{<:Any,<:Dimensions}) where {T,R,Q<:Quantity{T,SymbolicDimensions{R}}}
-    return new_quantity(
-        Q,
-        convert(T, ustrip(q)),
-        SymbolicDimensions{R}(;
-            m=ulength(q),
-            kg=umass(q),
-            s=utime(q),
-            A=ucurrent(q),
-            K=utemperature(q),
-            cd=uluminosity(q),
-            mol=uamount(q),
-        )
-    )
+function Base.convert(::Type{Quantity{T,SymbolicDimensions{R}}}, q::Quantity{<:Any,<:Dimensions}) where {T,R}
+    syms = (:m, :kg, :s, :A, :K, :cd, :mol)
+    vals = (ulength(q), umass(q), utime(q), ucurrent(q), utemperature(q), uluminosity(q), uamount(q))
+    I = INDEX_TYPE[ALL_MAPPING[s] for (s, v) in zip(syms, vals) if !iszero(v)]
+    V = R[tryrationalize(R, v) for v in vals if !iszero(v)]
+    p = sortperm(I)
+    permute!(I, p)
+    permute!(V, p)
+    dims = SymbolicDimensions{R}(I, V)
+    return Quantity(convert(T, ustrip(q)), dims)
 end
-function Base.convert(::Type{Q}, q::Quantity{<:Any,<:SymbolicDimensions}) where {T,D<:Dimensions,Q<:Quantity{T,D}}
-    result = new_quantity(Q, ustrip(q), dim_type(Q))
+function Base.convert(::Type{Quantity{T,D}}, q::Quantity{<:Any,<:SymbolicDimensions}) where {T,D<:Dimensions}
+    result = Quantity(T(ustrip(q)), D())
     d = dimension(q)
     for (idx, value) in zip(getfield(d, :nzdims), getfield(d, :nzvals))
         if !iszero(value)
-            result = result * convert(Q, ALL_VALUES[idx]) ^ value
+            result = result * convert(Quantity{T,D}, ALL_VALUES[idx]) ^ value
         end
     end
     return result

test/unittests.jl

@@ -580,6 +580,8 @@ end
 
     # Test conversion
     @test typeof(SymbolicDimensions{Rational{Int}}(dimension(us"km/s"))) == SymbolicDimensions{Rational{Int}}
+    @test convert(Quantity{Float64,SymbolicDimensions}, u"kg") == us"1kg"
+    @test convert(Quantity{Float64,Dimensions}, us"3.5kg/s") == u"3.5kg/s"
 
     # Helpful error if symbol not found:
     sym5 = dimension(us"km/s")