From 3d5b2411044b381063b19b058fa2de5235808735 2013-02-25 15:22:07
From: Lance Edgar <lance@edbob.org>
Date: 2013-02-25 15:22:07
Subject: [PATCH] Added ``files`` module.

This will eventually supercede ``edbob.files``, but for now this commit adds
only three functions.  These just so happened to be ones needed to support some
code involving inventory count batches.

---

diff --git a/rattail/files.py b/rattail/files.py
new file mode 100644
index 0000000000000000000000000000000000000000..2fcb99574b51ab03aa70ed6972df31cd6ca0ac0b
--- /dev/null
+++ b/rattail/files.py
@@ -0,0 +1,94 @@
+#!/usr/bin/env python
+# -*- coding: utf-8  -*-
+################################################################################
+#
+#  Rattail -- Retail Software Framework
+#  Copyright © 2010-2012 Lance Edgar
+#
+#  This file is part of Rattail.
+#
+#  Rattail is free software: you can redistribute it and/or modify it under the
+#  terms of the GNU Affero General Public License as published by the Free
+#  Software Foundation, either version 3 of the License, or (at your option)
+#  any later version.
+#
+#  Rattail is distributed in the hope that it will be useful, but WITHOUT ANY
+#  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+#  FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for
+#  more details.
+#
+#  You should have received a copy of the GNU Affero General Public License
+#  along with Rattail.  If not, see <http://www.gnu.org/licenses/>.
+#
+################################################################################
+
+"""
+``rattail.files`` -- File Utilities
+
+This module contains various utility functions for use with the filesystem.
+"""
+
+import os.path
+import shutil
+import lockfile
+from datetime import datetime
+
+
+def count_lines(path):
+    """
+    Counts the number of lines in a text file.  Some attempt is made to ensure
+    cross-platform compatibility.
+
+    :param path: Path to the file.
+    :type path: string
+
+    :returns: Number of lines in the file.
+    :rtype: integer
+    """
+
+    f = open(path, 'rb')
+    lines = f.read().count('\n') + 1
+    f.close()
+    return lines
+
+
+def creation_time(path):
+    """
+    Returns the "naive" (i.e. not timezone-aware) creation timestamp for a
+    file.
+
+    :param path: Path to the file.
+    :type path: string
+
+    :returns: The creation timestamp for the file.
+    :rtype: ``datetime.datetime`` instance
+    """
+
+    time = os.path.getctime(path)
+    return datetime.fromtimestamp(time)
+
+
+def locking_copy(src, dst):
+    """
+    Implements a "locking" version of ``shutil.copy()``.
+
+    This function exists to provide a more atomic method for copying a file
+    into a folder which is being watched by a file monitor.  The assumption is
+    that the monitor is configured to expect "locks" and therefore only process
+    files once they have had their locks removed.
+
+    :param src: Path to the source file.
+    :type src: string
+
+    :param dst: Path to the destination file (or directory).
+    :type dst: string
+
+    :returns: ``None``
+    """
+
+    if os.path.isdir(dst):
+        fn = os.path.basename(src)
+        dst = os.path.join(dst, fn)
+
+    with lockfile.FileLock(dst):
+        shutil.copy(src, dst)