disable deepcopy on PyObject #757 (#1039)

* disable deepcopy on PyObject #757

* Update src/PyCall.jl

Co-authored-by: Steven G. Johnson <stevenj@mit.edu>

* fix deepcopy and add tests

* add another deepcopy test

* v1.95.2

* Update Project.toml

* Update test/runtests.jl

---------

Co-authored-by: Steven G. Johnson <stevenj@mit.edu>

Project.toml

@@ -1,7 +1,7 @@
 name = "PyCall"
 uuid = "438e738f-606a-5dbb-bf0a-cddfbfd45ab0"
 authors = ["Steven G. Johnson <stevenj@mit.edu>", "Yichao Yu <yyc1992@gmail.com>", "Takafumi Arakaki <aka.tkf@gmail.com>", "Simon Kornblith <simon@simonster.com>", "Páll Haraldsson <Pall.Haraldsson@gmail.com>", "Jon Malmaud <malmaud@gmail.com>", "Jake Bolewski <jakebolewski@gmail.com>", "Keno Fischer <keno@alumni.harvard.edu>", "Joel Mason <jobba1@hotmail.com>", "Jameson Nash <vtjnash@gmail.com>", "The JuliaPy development team"]
-version = "1.95.2"
+version = "1.96.0"
 
 [deps]
 Conda = "8f4d0f93-b110-5947-807f-2305c1781a2d"

src/PyCall.jl

@@ -979,6 +979,16 @@ include("serialize.jl")
 
 include("pyinit.jl")
 
+const _deepcopy = PyNULL()
+
+function Base.deepcopy_internal(obj::PyObject, stackdict::Base.IdDict)
+    haskey(stackdict, obj) && return stackdict[obj]
+    ispynull(_deepcopy) && copy!(_deepcopy, pyimport("copy")["deepcopy"])
+    ret =  pycall(_deepcopy, PyObject, obj)
+    stackdict[obj] = ret
+    ret
+end
+
 #########################################################################
 
 include("precompile.jl")

test/runtests.jl

@@ -620,6 +620,45 @@ const PyInt = pyversion < v"3" ? Int : Clonglong
     @test_throws ArgumentError float(pybuiltin("type"))
 end
 
+@testset "deepcopy #757" begin
+    l = py"[1,2,3]"o
+    l2 = deepcopy(l)
+    @test l == l2
+    l2.append(4)
+    @test l != l2
+    @test collect(l2) == [1,2,3,4]
+    @test collect(l) == [1,2,3]
+
+    obj = py"""
+    class C757:
+        def __init__(self, a, b):
+            self.a = a
+            self.b = b
+    """
+    obj = py"C757(C757(1,2), C757(3,4))"o
+    obj2 = deepcopy(obj)
+    @test PyPtr(obj) != PyPtr(obj2) # make sure a new Python object is created
+    @test obj.a.a == obj2.a.a
+    @test obj.a.b == obj2.a.b
+    @test obj.b.a == obj2.b.a
+    @test obj.b.b == obj2.b.b
+    obj.a = 3
+    @test obj.a == 3
+    @test obj2.a.a == 1
+    @test obj2.a.b == 2
+
+    struct S;a;b;end
+
+    c = py"C757(1,2)"
+    obj = S(c, c)
+    obj2 = deepcopy(obj)
+    @test obj.a === obj.b
+    @test obj2.a === obj2.b
+    obj.a.a = 4
+    @test obj.a.a == 4
+    @test obj2.a.a == 1
+end
+
 ######################################################################
 #@pydef tests: type declarations need to happen at top level
 
@@ -855,3 +894,4 @@ end
     @test_throws PyCall.PyError a.a = 0
     @test_throws KeyError a.a = 1
 end
+