Impl constants module (#63)

* prepare `pyconstant` variable and export it from SciPy

* collect constant-like objects and store them in d["constant"]

* implement `constants` module

* mv docstring

* fix

* write comment because the implenentation of `constants` module is more complicated than other submodules of SciPy.jl

* add type checking test

* write more tests

* fix docstring

* add comment

* Revert "add comment"

This reverts commit 939e506.

* Revert "collect constant-like objects and store them in d["constant"]"

This reverts commit 1a7b6c9.

* rewrite constants.jl

* add test

src/SciPy.jl

@@ -15,7 +15,7 @@ export print_configulations
 export cluster, constants, fft, integrate, interpolate, io, linalg, ndimage, odr
 export optimize, signal, sparse, spatial, stats, special
 # raw PyObject modules
-export pystats, pyoptimize, pyinterpolate, pyspatial
+export pyconstants, pystats, pyoptimize, pyinterpolate, pyspatial
 
 
 const scipy = PyNULL()
@@ -73,31 +73,8 @@ julia> SciPy.cluster.vq.kmeans(whitened, [whitened[1,:] whitened[3,:]] )
 """
 const cluster = PyNULL()
 
-"""
-scipy.constants module
-
-- [Constants (scipy.constants) Reference Guide](https://docs.scipy.org/doc/scipy/reference/constants.html)
-
-# Examples
-
-You can access each constants:
-
-```julia-repl
-julia> SciPy.constants.golden
-1.618033988749895
-
-julia> SciPy.constants.physical_constants["electron mass"] 
-(9.10938356e-31, "kg", 1.1e-38)
-
-julia> SciPy.constants.convert_temperature([-40, 40.0], "Celsius", "Kelvin") 
-
-2-element Array{Float64,1}:
- 233.14999999999998
- 313.15
-
-```
-"""
-const constants = PyNULL()
+const pyconstants = PyNULL()
+include("constants.jl")
 
 """
 scipy.fft module
@@ -326,7 +303,6 @@ Module initialization function
 function __init__()
     copy!(scipy, pyimport_conda("scipy", "scipy"))
     copy!(cluster, pyimport_conda("scipy.cluster", "scipy"))
-    copy!(constants, pyimport_conda("scipy.constants", "scipy"))
     copy!(fft, pyimport_conda("scipy.fft", "scipy"))
     copy!(integrate, pyimport_conda("scipy.integrate", "scipy"))
     copy!(io, pyimport_conda("scipy.io", "scipy"))
@@ -341,6 +317,7 @@ function __init__()
     copy!(pystats, pyimport_conda("scipy.stats", "scipy"))
     copy!(pyoptimize, pyimport_conda("scipy.optimize", "scipy"))
     copy!(pyinterpolate, pyimport_conda("scipy.interpolate", "scipy"))
+    copy!(pyconstants, pyimport_conda("scipy.constants", "scipy"))
 end
 
 """

src/constants.jl

@@ -0,0 +1,73 @@
+"""
+scipy.constants module
+
+- [Constants (scipy.constants) Reference Guide](https://docs.scipy.org/doc/scipy/reference/constants.html)
+
+# Examples
+
+You can access each constants:
+
+```julia-repl
+julia> SciPy.constants.golden
+1.618033988749895
+
+julia> SciPy.constants.physical_constants["electron mass"]
+(9.10938356e-31, "kg", 1.1e-38)
+
+julia> SciPy.constants.convert_temperature([-40, 40.0], "Celsius", "Kelvin")
+2-element Vector{Float64}:
+ 233.14999999999998
+ 313.15
+
+```
+"""
+module constants
+
+using PyCall
+
+pyimport_conda("scipy", "scipy")
+@pyinclude(joinpath(pkgdir(@__MODULE__), "src", "scipy_api_list.py"))
+apis = py"generate_scipy_apis"("constants")
+
+all_properties = [apis["function"]; apis["class"]]
+
+import ..pyconstants
+
+import ..LazyHelp
+
+const _ignore_funcs = ["constants"]
+
+for f in [apis["function"]; apis["class"]]
+    f in _ignore_funcs && continue
+
+    sf = Symbol(f)
+    @eval @doc LazyHelp(pyconstants, $f) $sf(args...; kws...) =
+        pycall(pyconstants.$f, PyAny, args...; kws...)
+end
+
+function __init__()
+    copy!(pyconstants, pyimport_conda("scipy.constants", "scipy"))
+
+    #=
+    The following metaprogramming will generate expressions like:
+
+    const zero_Celsius = 273.15
+    const golden = 1.618033988749895
+    const centi = 0.01
+
+    =#
+    for f in pyconstants.__all__ |> unique |> sort
+        f in _ignore_funcs && continue # just in case
+        a = pybuiltin("getattr")(pyconstants, f)
+        if a isa PyObject
+            # The variable `a` should be python function, class or module
+            continue
+        else
+            # The variable `a` is converted in a Julia's native type. We assume this is a constant value.
+            sf = Symbol(f)
+            @eval @doc LazyHelp(pyconstants, $f) const $sf = $a
+        end
+    end
+end
+
+end # module

test/runtests.jl

@@ -20,7 +20,18 @@ using Test
     end
 
     @testset "constants" begin
+        @test constants.zero_Celsius == 273.15
         @test constants.golden == 1.618033988749895
+        @test constants.centi == 0.01
+
+        @test typeof(pyconstants.zero_Celsius) == typeof(constants.zero_Celsius)
+        @test typeof(pyconstants.golden) == typeof(constants.golden)
+        @test typeof(pyconstants.centi) == typeof(constants.centi)
+
+        @test constants.convert_temperature([-40, 40.0], "Celsius", "Kelvin") ≈ [233.14999999999998, 313.15]
+
+        @test typeof(pyconstants.physical_constants) == typeof(constants.physical_constants)
+        @test constants.physical_constants["electron mass"] == (9.1093837015e-31, "kg", 2.8e-40)
     end
 
     @testset "fft" begin