add print_version method

Author: samuelcolvin

tests/test_main.py

@@ -52,6 +52,11 @@ def test_different_compression():
     assert len(delta_a) < len(delta_b)
 
 
+def test_version():
+    # can't easily test output as capsys doesn't capture output of print_version
+    xdelta3.print_version()
+
+
 def test_readme():
     value_one = b'wonderful string to demonstrate xdelta3, much of these two strings is the same.'
     value_two = b'different string to demonstrate xdelta3, much of these two strings is the same.'

xdelta3/_xdelta3.c

@@ -56,8 +56,16 @@ static PyObject * xdelta3_execute(PyObject *self, PyObject *args)
   return NULL;
 }
 
+static PyObject * xdelta3_version(PyObject *self, PyObject *args)
+{
+  int result = main_version();
+  PyObject *ret = Py_BuildValue("i", result);
+  return ret;
+}
+
 static PyMethodDef xdelta3_methods[] = {
   {"execute",  xdelta3_execute, METH_VARARGS, "xdelta3 encode or decode"},
+  {"version",  xdelta3_version, METH_VARARGS, "print xdelta3 version info"},
   {NULL, NULL, 0, NULL}
 };
 

xdelta3/main.py

@@ -1,14 +1,18 @@
+import sys
 from enum import IntEnum
 
 import _xdelta3
 from _xdelta3 import NoDeltaFound, XDeltaError  # noqa
 
+from .version import VERSION
+
 __all__ = [
     'NoDeltaFound',
     'XDeltaError',
     'Flags',
     'encode',
     'decode',
+    'print_version',
 ]
 
 
@@ -85,7 +89,7 @@ def encode(original: bytes, new_value: bytes, flags: int=Flags.COMPLEVEL_9) -> b
     return _xdelta3.execute(new_value, original, flags, 0)
 
 
-def decode(original: bytes, delta: bytes, flags: int=Flags.COMPLEVEL_9):
+def decode(original: bytes, delta: bytes, flags: int=Flags.COMPLEVEL_9) -> bytes:
     """
     Decode a delta to calculate a new value from the original and a delta.
 
@@ -98,3 +102,12 @@ def decode(original: bytes, delta: bytes, flags: int=Flags.COMPLEVEL_9):
     :return: new byte string from applying delta to original
     """
     return _xdelta3.execute(delta, original, flags, 1)
+
+
+def print_version():
+    """
+    Print version info for xdelta3-python and the xdelta3 c library.
+    """
+    print('xdelta3-python:', VERSION, file=sys.stderr)
+    print('xdelta3-c library:', file=sys.stderr)
+    _xdelta3.version()