Implicity convert function into FunctionWrappersWrapper (#54)

* Added FunctionWrappersWrapper constructor for the case where type parameters are specified but only the function to be wrapped is provied as an argument.

* Changed arguments types in test from Int to Float32 because calculating exp and cos of integer really doesn't make sense.  Actually check the value of the wrapped cos.

* Added specializations of Base.convert for FunctionWrappersWrapper based on new constructor.

* Added a docstring for new constructor

* Fixed formatting

Author: densmojd

src/FunctionWrappersWrappers.jl

@@ -111,6 +111,25 @@ end
 
 TruncatedStacktraces.@truncate_stacktrace FunctionWrappersWrapper
 
+"""
+    FunctionWrappersWrapper{FW, P, CS}(f)
+
+Create a `FunctionWrappersWrapper` when the type parameters are specified.
+
+# Arguments
+- `f`: The function to wrap
+
+# Type parameters
+- `FW`: Tuple type of `FunctionWrapper`s
+- `P`: Fallback policy (`Strict`, `AllowAll`, or `AllowNonIsBits`)
+- `CS`: Cache storage type (`NoCacheStorage`, `SingleCacheStorage`, `DictCacheStorage`)
+"""
+function FunctionWrappersWrapper{FW, P, CS}(f) where {K, FW <: NTuple{K, Any}, P, CS}
+    fw = ntuple(i -> FW.parameters[i](f), Val(K))
+    cs = CS()
+    return FunctionWrappersWrapper{FW, P, CS}(fw, cs)
+end
+
 """
     FunctionWrappersWrapper(f, argtypes, rettypes; cache=SingleCache(), policy=AllowNonIsBits())
 
@@ -137,6 +156,8 @@ function FunctionWrappersWrapper(
     return FunctionWrappersWrapper{typeof(fwt), typeof(policy), typeof(cs)}(fwt, cs)
 end
 
+Base.convert(::Type{T}, obj) where {T <: FunctionWrappersWrapper} = T(obj)
+Base.convert(::Type{T}, obj::T) where {T <: FunctionWrappersWrapper} = obj
 
 # ============================================================================
 # Call dispatch — entry point

test/basictests.jl

@@ -243,3 +243,22 @@ end
     # Float32 is isbits mismatch → errors
     @test_throws FunctionWrappersWrappers.NoFunctionWrapperFoundError fww(4.0f0, 8.0f0)
 end
+
+@testset "Conversion" begin
+    fww_exp = FunctionWrappersWrapper(
+        exp,
+        (Tuple{Float64}, Tuple{Float32}),
+        (Float64, Float32)
+    )
+    FWW = typeof(fww_exp)
+
+    fww_cos = FWW(cos)
+    @test typeof(fww_cos) == FWW
+    @test fww_cos(0.5) == cos(0.5)
+
+    fww_vector = FWW[sin, tan, log]
+    @test eltype(fww_vector) == FWW
+    fww_vector[1](0.5) == sin(0.5)
+    fww_vector[2](0.5) == tan(0.5)
+    fww_vector[3](0.5) == log(0.5)
+end