update TarFile usage

devtools/tarball.py

@@ -1,5 +1,5 @@
+from contextlib import closing
 import os.path
-import gzip
 import tarfile
 
 TARGZ_DEFAULT_COMPRESSION_LEVEL = 9
@@ -29,25 +29,18 @@ def visit(tar, dirname, names):
                 path_in_tar = archive_name(path)
                 tar.add(path, path_in_tar)
     compression = TARGZ_DEFAULT_COMPRESSION_LEVEL
-    tar = tarfile.TarFile.gzopen(tarball_path, 'w', compresslevel=compression)
-    try:
+    with closing(tarfile.TarFile.open(tarball_path, 'w:gz',
+            compresslevel=compression)) as tar:
         for source in sources:
             source_path = source
             if os.path.isdir(source):
                 os.path.walk(source_path, visit, tar)
             else:
                 path_in_tar = archive_name(source_path)
                 tar.add(source_path, path_in_tar)      # filename, arcname
-    finally:
-        tar.close()
 
 def decompress(tarball_path, base_dir):
     """Decompress the gzipped tarball into directory base_dir.
     """
-    # !!! This class method is not documented in the online doc
-    # nor is bz2open!
-    tar = tarfile.TarFile.gzopen(tarball_path, mode='r')
-    try:
+    with closing(tarfile.TarFile.open(tarball_path)) as tar:
         tar.extractall(base_dir)
-    finally:
-        tar.close()