Expose docs to Julia (#354)

* Expose docs to Julia

* Returns docstrings as Text

* Add tests

src/PyCall.jl

@@ -711,6 +711,14 @@ for (mime, method) in ((MIME"text/html", "_repr_html_"),
     end
 end
 
+#########################################################################
+# Expose Python docstrings to the Julia doc system
+
+if isdefined(Docs, :getdoc)  # Introduced in Julia .6
+    Docs.getdoc(o::PyObject) = Text(String(o["__doc__"]))
+end
+
+
 #########################################################################
 
 include("pyeval.jl")

test/runtests.jl

@@ -338,3 +338,15 @@ let weakdict = pyimport("weakref")["WeakValueDictionary"]
     #  weak references to type objects)
     @test weakdict(Dict(3=>weakdict)) == Dict(3=>weakdict)
 end
+
+# Expose python docs to Julia doc system
+if isdefined(Docs, :getdoc)
+    py"""
+    def foo():
+        "foo docstring"
+        return 0
+    """
+    foo = py"foo"
+    # use 'content' since `Text` objects test equality by object identity
+    @test @doc(foo).content == "foo docstring"
+end