undocument C.CTX and provide alternatives

Author: Christopher Doris

docs/src/pycall.md

@@ -10,7 +10,7 @@ On this page, we give some tips for migrating between the two modules and a comp
   - On Unix (Linux, Mac, etc.) the Python interpreter used by PythonCall and PyCall must be the same (see below).
   - On Windows, it appears to be possible for PythonCall and PyCall to use different interpreters.
 - To force PythonCall to use the same Python interpreter as PyCall, set the environment variable `JULIA_PYTHONCALL_EXE` to `"@PyCall"`. Note that this will opt out of automatic dependency management using CondaPkg.
-- Alternatively, to force PyCall to use the same interpreter as PythonCall, set the environment variable `PYTHON` to `PythonCall.C.CTX.exe_path` and then `Pkg.build("PyCall")`. You will need to do this each time you change project, because PythonCall by default uses a different Python for each project.
+- Alternatively, to force PyCall to use the same interpreter as PythonCall, set the environment variable `PYTHON` to `PythonCall.python_executable_path()` and then `Pkg.build("PyCall")`. You will need to do this each time you change project, because PythonCall by default uses a different Python for each project.
 
 ## Comparison
 

src/C/C.jl

@@ -17,6 +17,7 @@ include("pointers.jl")
 include("extras.jl")
 include("context.jl")
 include("gil.jl")
+include("api.jl")
 
 function __init__()
     init_context()

src/C/api.jl

@@ -0,0 +1,27 @@
+"""
+    python_executable_path()
+
+Path to the Python interpreter, or `missing` if not known.
+"""
+python_executable_path() = CTX.exe_path
+
+"""
+    python_library_path()
+
+Path to libpython, or `missing` if not known.
+"""
+python_library_path() = CTX.lib_path
+
+"""
+    python_library_handle()
+
+Handle to the open libpython, or `C_NULL` if not known.
+"""
+python_library_handle() = CTX.lib_ptr
+
+"""
+    python_version()
+
+The version of Python, or `missing` if not known.
+"""
+python_version() = CTX.version

src/PythonCall.jl

@@ -17,13 +17,16 @@ include("Compat/Compat.jl")
 for m in [:Core, :Convert, :PyMacro, :Wrap, :JlWrap, :Compat]
     for k in names(@eval($m))
         if k != m
-            @eval using .$m: $k
+            @eval const $k = $m.$k
             @eval export $k
         end
     end
 end
 
 # non-exported API
+for k in [:python_executable_path, :python_library_path, :python_library_handle, :python_version]
+    @eval const $k = C.$k
+end
 for k in [:pynew, :pyisnull, :pycopy!, :getptr, :pydel!, :unsafe_pynext, :PyNULL, :CONFIG]
     @eval const $k = Core.$k
 end

test/C.jl

@@ -1 +1,18 @@
-# TODO
+@testitem "python info" begin
+    @testset "python_executable_path" begin
+        @test PythonCall.python_executable_path() isa String
+        @test occursin("python", PythonCall.python_executable_path())
+    end
+    @testset "python_library_path" begin
+        @test PythonCall.python_library_path() isa String
+        @test occursin("python", PythonCall.python_library_path())
+    end
+    @testset "python_library_handle" begin
+        @test PythonCall.python_library_handle() isa Ptr{Cvoid}
+        @test PythonCall.python_library_handle() != C_NULL
+    end
+    @testset "python_version" begin
+        @test PythonCall.python_version() isa VersionNumber
+        @test PythonCall.python_version().major == 3
+    end
+end