Remove Client __del__ in favor of context management

[bup.git] / lib / bup / compat.py

diff --git a/lib/bup/compat.py b/lib/bup/compat.py
index fb45ead5d6e100fdcc0d37910d42e69f6e72793c..fbeee4a478fd3da42976d8b50a05f03558a2996d 100644 (file)
--- a/lib/bup/compat.py
+++ b/lib/bup/compat.py
@@ -13,9 +13,12 @@ py3 = py_maj >= 3
 if py3:
 
     # pylint: disable=unused-import
+    from contextlib import nullcontext
     from os import environb as environ
     from os import fsdecode, fsencode
     from shlex import quote
+    # pylint: disable=undefined-variable
+    # (for python2 looking here)
     ModuleNotFoundError = ModuleNotFoundError
     input = input
     range = range
@@ -38,18 +41,19 @@ if py3:
         return ex
 
     class pending_raise:
-        """Rethrow either the provided ex, or any exception raised by the with
-        statement body.  (Supports Python 2 compatibility.)
+        """If rethrow is true, rethrow ex (if any), unless the body throws.
+
+        (Supports Python 2 compatibility.)
 
         """
-        def __init__(self, ex):
+        def __init__(self, ex, rethrow=True):
             self.ex = ex
+            self.rethrow = rethrow
         def __enter__(self):
             return None
         def __exit__(self, exc_type, exc_value, traceback):
-            if not exc_type:
+            if not exc_type and self.ex and self.rethrow:
                 raise self.ex
-            return None
 
     def items(x):
         return x.items()
@@ -79,6 +83,8 @@ if py3:
 
 else:  # Python 2
 
+    from contextlib import contextmanager
+
     ModuleNotFoundError = ImportError
 
     def fsdecode(x):
@@ -94,9 +100,18 @@ else:  # Python 2
     # pylint: disable=unused-import
     from bup.py2raise import reraise
 
+    @contextmanager
+    def nullcontext(enter_result=None):
+        yield enter_result
+
+    # on py3 this causes errors, obviously
+    # pylint: disable=undefined-variable
     input = raw_input
+    # pylint: disable=undefined-variable
     range = xrange
+    # pylint: disable=undefined-variable
     str_type = basestring
+    # pylint: disable=undefined-variable
     int_types = (int, long)
 
     hexstr = hexlify
@@ -120,24 +135,28 @@ else:  # Python 2
         return ex
 
     class pending_raise:
-        """Rethrow either the provided ex, or any exception raised by the with
-        statement body, after making ex the __context__ of the newer
-        exception (assuming there's no existing __context__).  Ensure
-        the exceptions have __tracebacks__.  (Supports Python 2
-        compatibility.)
+        """If rethrow is true, rethrow ex (if any), unless the body throws.
+
+        If the body does throw, make any provided ex the __context__
+        of the newer exception (assuming there's no existing
+        __context__).  Ensure the exceptions have __tracebacks__.
+        (Supports Python 2 compatibility.)
 
         """
-        def __init__(self, ex):
+        def __init__(self, ex, rethrow=True):
             self.ex = ex
+            self.rethrow = rethrow
         def __enter__(self):
-            add_ex_tb(self.ex)
-            return None
+            if self.ex:
+                add_ex_tb(self.ex)
         def __exit__(self, exc_type, exc_value, traceback):
-            if not exc_type:
+            if exc_value:
+                if self.ex:
+                    add_ex_tb(exc_value)
+                    add_ex_ctx(exc_value, self.ex)
+                return
+            if self.rethrow and self.ex:
                 raise self.ex
-            add_ex_tb(exc_value)
-            add_ex_ctx(exc_value, self.ex)
-            return None
 
     def dump_traceback(ex):
         stack = [ex]