Merge pull request #1 from ddelange/patch-1

Allow protocol=0, default to HIGHEST_PROTOCOL

README.md

@@ -53,7 +53,11 @@ Pickleclip will copy any python object supported by pickle (or dill) into your c
 
 ### Copying from Python 3 to Python 2 using pickle
 
-There are some known compatibility problems with copying and pasting code from Python 3 to Python 2, but some of those problems can be solved by using the `protocol` kwarg:
+To get Python 3 objects to unpickle on Python 2, specify `protocol=2` when copying. Although pickle will try to map the new Python 3 names to the old module names used in Python 2, so that the pickle data stream is readable with Python 2, this does not come without limitations.
+
+Going from Python 2 to Python 3 is even less trivial, and will mostly only work for the simplest cases. See also [pickle-compat](https://pypi.org/project/pickle-compat/).
+
+By default, the highest [pickle protocol](https://docs.python.org/3/library/pickle.html#pickle-protocols) available to the interpreter is used. The higher the protocol used, the more recent the version of Python needed to read the pickle produced.
 
 ##### Python 3 shell:
 
@@ -72,8 +76,6 @@ In [2]: picklec.paste()
 Out[2]: {'hello': 'world'}
 ```
 
-Since the PY2's pickle version can't handle the PY3's protocol number (which is 3), you'll need to force the PY3 pickle to use `protocol = 2`.
-
 ### Copying from different Python versions using dill
 
 It should work fine with basic objects (str, int, float, list, set, dict...), but it won't work with nothing too "fancy", (functions, custom objects...).

pickleclip/base.py

@@ -7,8 +7,7 @@
 import six
 
 
-def copy(obj, protocol=None, serializer=pickle):
-    protocol = protocol or (2 if six.PY2 else 3)
+def copy(obj, protocol=-1, serializer=pickle):
     dump = serializer.dumps(obj, protocol=protocol)
     pyperclip.copy(dump.decode('latin1'))