argv: forward changes to sys.argv. Fixes #2

senf/_argv.py

@@ -14,17 +14,21 @@
 
 import sys
 import ctypes
+import collections
 
 from ._compat import PY2
-from ._fsnative import is_unix
+from ._fsnative import is_win, _fsn2legacy
 from . import _winapi as winapi
 
 
-def create_argv():
-    """Returns a unicode argv under Windows and standard sys.argv otherwise"""
+def _get_win_argv():
+    """Returns a unicode argv under Windows and standard sys.argv otherwise
 
-    if is_unix or not PY2:
-        return sys.argv
+    Returns:
+        List[`fsnative`]
+    """
+
+    assert is_win
 
     argc = ctypes.c_int()
     try:
@@ -43,4 +47,40 @@ def create_argv():
     return res
 
 
-argv = create_argv()
+class Argv(collections.MutableSequence, list):
+    """List[`fsnative`]: Like `sys.argv` but contains unicode
+    keys and values under Windows + Python 2
+    """
+
+    def __init__(self):
+        if PY2 and is_win:
+            self._argv = _get_win_argv()
+        else:
+            self._argv = sys.argv
+
+    def __getitem__(self, index):
+        return self._argv[index]
+
+    def __setitem__(self, index, value):
+        self._argv[index] = value
+        try:
+            sys.argv[index] = _fsn2legacy(value)
+        except IndexError:
+            pass
+
+    def __delitem__(self, index):
+        del self._argv[index]
+        try:
+            del sys.argv[index]
+        except IndexError:
+            pass
+
+    def __len__(self):
+        return len(self._argv)
+
+    def insert(self, index, value):
+        self._argv.insert(index, value)
+        sys.argv.insert(index, _fsn2legacy(value))
+
+
+argv = Argv()

senf/_environ.py

@@ -17,26 +17,10 @@
 import collections
 
 from ._compat import text_type, PY2
-from ._fsnative import path2fsn, is_win, _encoding
+from ._fsnative import path2fsn, is_win, _fsn2legacy
 from . import _winapi as winapi
 
 
-def _fsn2legacy(path):
-    """Takes a fsnative path and returns a path that can be put into os.environ
-    or sys.argv. Might result in a mangled path on Python2 + Windows.
-    Can't fail.
-
-    Args:
-        path (fsnative)
-    Returns:
-        str
-    """
-
-    if PY2 and is_win:
-        return path.encode(_encoding, "replace")
-    return path
-
-
 def get_windows_env_var(key):
     """Get an env var.
 

senf/_fsnative.py

@@ -52,6 +52,22 @@ def _decode_surrogatepass(data, codec):
             raise
 
 
+def _fsn2legacy(path):
+    """Takes a fsnative path and returns a path that can be put into os.environ
+    or sys.argv. Might result in a mangled path on Python2 + Windows.
+    Can't fail.
+
+    Args:
+        path (fsnative)
+    Returns:
+        str
+    """
+
+    if PY2 and is_win:
+        return path.encode(_encoding, "replace")
+    return path
+
+
 def _fsnative(text):
     if not isinstance(text, text_type):
         raise TypeError("%r needs to be a text type (%r)" % (text, text_type))

tests/test_api.py

@@ -102,6 +102,17 @@ def preserve_environ(environ=environ):
             environ[key] = value
 
 
+@contextlib.contextmanager
+def preserve_argv(argv=argv):
+    old = argv[:]
+    if argv is not sys.argv:
+        with preserve_argv(sys.argv):
+            yield
+    else:
+        yield
+    argv[:] = old
+
+
 @contextlib.contextmanager
 def capture_output(data=None):
     """
@@ -614,6 +625,25 @@ def test_argv():
     assert all(isinstance(v, fsnative) for v in argv)
 
 
+def test_argv_change():
+    with preserve_argv():
+        argv.append(fsnative(u"\u1234"))
+        assert argv[-1] == fsnative(u"\u1234")
+        assert len(sys.argv) == len(argv)
+        assert sys.argv[-1] in (fsnative(u"\u1234"), "?")
+        argv[-1] = fsnative(u"X")
+        assert path2fsn(sys.argv[-1]) == argv[-1]
+        del argv[-1]
+        assert len(sys.argv) == len(argv)
+
+    with preserve_argv():
+        sys.argv[0] = sys.argv[0] + sys.argv[0]
+        if path2fsn(sys.argv[0]) != argv[0]:
+            del sys.argv[:]
+            argv[0] = fsnative(u"")
+            del argv[0]
+
+
 def test_getcwd():
     assert isinstance(getcwd(), fsnative)