Base.convert(::Type{Operator}, ::Operator) (#107)

* Base.convert(::Type{Operator}, ::Operator)

* do not convert if the type is already the same

This is expected by the convert api, e.g.

```
julia> a = [1]
1-element Vector{Int64}:
 1

julia> b = convert(Vector{Int},a)
1-element Vector{Int64}:
 1

julia> a[1] = 2; b
1-element Vector{Int64}:
 2
```

Author: Krastanov

Project.toml

@@ -1,6 +1,6 @@
 name = "QuantumOpticsBase"
 uuid = "4f57444f-1401-5e15-980d-4471b28d5678"
-version = "0.4.3"
+version = "0.4.4"
 
 [deps]
 Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"

src/operators_dense.jl

@@ -32,6 +32,13 @@ Base.eltype(op::Operator) = eltype(op.data)
 Base.eltype(::Type{T}) where {BL,BR,D,T<:Operator{BL,BR,D}} = eltype(D)
 Base.size(op::Operator) = size(op.data)
 Base.size(op::Operator, d::Int) = size(op.data, d)
+function Base.convert(::Type{Operator{BL,BR,T}}, op::Operator{BL,BR,S}) where {BL,BR,T,S}
+    if T==S
+        return op
+    else
+        return Operator{BL,BR,T}(op.basis_l, op.basis_r, convert(T, op.data))
+    end
+end
 
 # Convert data to CuArray with cu(::Operator)
 Adapt.adapt_structure(to, x::Operator) = Operator(x.basis_l, x.basis_r, Adapt.adapt(to, x.data))

test/test_operators.jl

@@ -140,4 +140,9 @@ Lop1 = LazyTensor(b1^2, b2^2, 2, sparse(randoperator(b1, b2)))
 @test_throws ErrorException size(dense(Lop1),  0) # check for consistency
 @test_throws ErrorException size(dense(Lop1), -1)
 
+# issue 106 | https://github.com/qojulia/QuantumOpticsBase.jl/issues/106
+a = destroy(FockBasis(5))
+@test dagger(a^2) == dagger(a)^2
+@test convert(Base._return_type(*, Tuple{typeof(a'), typeof(a')}), a') == a'
+
 end # testset