enable config parsers to be used as context managers

if used as context managers, the parsers will automatically release their file locks.

Author: boidolr

git/config.py

@@ -95,7 +95,10 @@ class SectionConstraint(object):
     """Constrains a ConfigParser to only option commands which are constrained to
     always use the section we have been initialized with.
 
-    It supports all ConfigParser methods that operate on an option"""
+    It supports all ConfigParser methods that operate on an option.
+
+    :note:
+        If used as a context manager, will release the wrapped ConfigParser."""
     __slots__ = ("_config", "_section_name")
     _valid_attrs_ = ("get_value", "set_value", "get", "set", "getint", "getfloat", "getboolean", "has_option",
                      "remove_section", "remove_option", "options")
@@ -129,6 +132,12 @@ def release(self):
         """Equivalent to GitConfigParser.release(), which is called on our underlying parser instance"""
         return self._config.release()
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exception_type, exception_value, traceback):
+        self.release()
+
 
 class GitConfigParser(with_metaclass(MetaParserBuilder, cp.RawConfigParser, object)):
 
@@ -145,7 +154,9 @@ class GitConfigParser(with_metaclass(MetaParserBuilder, cp.RawConfigParser, obje
 
     :note:
         The config is case-sensitive even when queried, hence section and option names
-        must match perfectly."""
+        must match perfectly.
+        If used as a context manager, will release the locked file. This parser cannot
+        be used afterwards."""
 
     #{ Configuration
     # The lock type determines the type of lock to use in new configuration readers.
@@ -216,6 +227,12 @@ def __del__(self):
         # NOTE: only consistent in PY2
         self.release()
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exception_type, exception_value, traceback):
+        self.release()
+
     def release(self):
         """Flush changes and release the configuration write lock. This instance must not be used anymore afterwards.
         In Python 3, it's required to explicitly release locks and flush changes, as __del__ is not called

git/repo/base.py

@@ -403,7 +403,7 @@ def config_writer(self, config_level="repository"):
         """
         :return:
             GitConfigParser allowing to write values of the specified configuration file level.
-            Config writers should be retrieved, used to change the configuration ,and written
+            Config writers should be retrieved, used to change the configuration, and written
             right away as they will lock the configuration file in question and prevent other's
             to write it.
 

git/test/test_config.py

@@ -139,57 +139,49 @@ def check_test_value(cr, value):
 
         # PREPARE CONFIG FILE A
         fpa = os.path.join(rw_dir, 'a')
-        cw = GitConfigParser(fpa, read_only=False)
-        write_test_value(cw, 'a')
-
-        fpb = os.path.join(rw_dir, 'b')
-        fpc = os.path.join(rw_dir, 'c')
-        cw.set_value('include', 'relative_path_b', 'b')
-        cw.set_value('include', 'doesntexist', 'foobar')
-        cw.set_value('include', 'relative_cycle_a_a', 'a')
-        cw.set_value('include', 'absolute_cycle_a_a', fpa)
-        cw.release()
+        with GitConfigParser(fpa, read_only=False) as cw:
+            write_test_value(cw, 'a')
+
+            fpb = os.path.join(rw_dir, 'b')
+            fpc = os.path.join(rw_dir, 'c')
+            cw.set_value('include', 'relative_path_b', 'b')
+            cw.set_value('include', 'doesntexist', 'foobar')
+            cw.set_value('include', 'relative_cycle_a_a', 'a')
+            cw.set_value('include', 'absolute_cycle_a_a', fpa)
         assert os.path.exists(fpa)
 
         # PREPARE CONFIG FILE B
-        cw = GitConfigParser(fpb, read_only=False)
-        write_test_value(cw, 'b')
-        cw.set_value('include', 'relative_cycle_b_a', 'a')
-        cw.set_value('include', 'absolute_cycle_b_a', fpa)
-        cw.set_value('include', 'relative_path_c', 'c')
-        cw.set_value('include', 'absolute_path_c', fpc)
-        cw.release()
+        with GitConfigParser(fpb, read_only=False) as cw:
+            write_test_value(cw, 'b')
+            cw.set_value('include', 'relative_cycle_b_a', 'a')
+            cw.set_value('include', 'absolute_cycle_b_a', fpa)
+            cw.set_value('include', 'relative_path_c', 'c')
+            cw.set_value('include', 'absolute_path_c', fpc)
 
         # PREPARE CONFIG FILE C
-        cw = GitConfigParser(fpc, read_only=False)
-        write_test_value(cw, 'c')
-        cw.release()
+        with GitConfigParser(fpc, read_only=False) as cw:
+            write_test_value(cw, 'c')
 
-        cr = GitConfigParser(fpa, read_only=True)
-        for tv in ('a', 'b', 'c'):
-            check_test_value(cr, tv)
-        # end for each test to verify
-        assert len(cr.items('include')) == 8, "Expected all include sections to be merged"
-        cr.release()
+        with GitConfigParser(fpa, read_only=True) as cr:
+            for tv in ('a', 'b', 'c'):
+                check_test_value(cr, tv)
+            # end for each test to verify
+            assert len(cr.items('include')) == 8, "Expected all include sections to be merged"
 
         # test writable config writers - assure write-back doesn't involve includes
-        cw = GitConfigParser(fpa, read_only=False, merge_includes=True)
-        tv = 'x'
-        write_test_value(cw, tv)
-        cw.release()
+        with GitConfigParser(fpa, read_only=False, merge_includes=True) as cw:
+            tv = 'x'
+            write_test_value(cw, tv)
 
-        cr = GitConfigParser(fpa, read_only=True)
-        self.failUnlessRaises(cp.NoSectionError, check_test_value, cr, tv)
-        cr.release()
+        with GitConfigParser(fpa, read_only=True) as cr:
+            self.failUnlessRaises(cp.NoSectionError, check_test_value, cr, tv)
 
         # But can make it skip includes alltogether, and thus allow write-backs
-        cw = GitConfigParser(fpa, read_only=False, merge_includes=False)
-        write_test_value(cw, tv)
-        cw.release()
+        with GitConfigParser(fpa, read_only=False, merge_includes=False) as cw:
+            write_test_value(cw, tv)
 
-        cr = GitConfigParser(fpa, read_only=True)
-        check_test_value(cr, tv)
-        cr.release()
+        with GitConfigParser(fpa, read_only=True) as cr:
+            check_test_value(cr, tv)
 
     def test_rename(self):
         file_obj = self._to_memcache(fixture_path('git_config'))

test-requirements.txt

@@ -1,3 +1,5 @@
+-r requirements.txt
+
 coverage
 flake8
 nose